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Abstract Newly synthesized vaccines prepared from formalin-killed bacteria Streptococcus pyogenes were investigated in the current study to evaluate the effectiveness of the newly synthesized vaccine as well as their safety by injected intraperitoneal. The study involved several steps 1st step is the preparation of the vaccine followed by the 2nd step: Evaluate the effectiveness and vaccine safety against pathogenic S. pyogenes through 4 different groups including control (Group I). Group II (Bacterial, infected group), Group III (Vaccine), and the Last group was the challenged group after the vaccination (Vacc + Bac). Different Immunological and biochemical parameters were measured in addition to hematological and histopathological examinations. For example, oxidative/antioxidants, inflammatory biomarkers, fragmentation and cell damage, and finally the histopathological study. The current study showed an increase in all oxidative, inflammatory, and cell damage (DNA fragmentation assays), additionally markedly elevation in histopathological cell damage in the infected group (Group II) compared with the control group. The vaccine and challenged after vaccination group (vaccine + Bacteria), showed great improvement in oxidative biomarkers (LPO) and an increase in antioxidants biomarkers (GSH, SOD, GST, DPPH, ABTS, GR and GPx), Also the inflammation and histopathological examination. The newly synthesized vaccine improved the resistance of Oreochromis niloticus and can be used as a preventive therapy agent for pathogenic bacteria S. pyogenes.

Abstract Background Gills monogenean infestation causes significant mortalities in cultured fishes as a result of respiratory manifestation. Medicinal plants are currently being heavily emphasized in aquaculture due to their great nutritional, therapeutic, antimicrobial activities, and financial value. Methods The current study is designed to assess the effect of garlic (Allium sativum) and onion (Allium cepa) extracts as a water treatment on the hematological profile, innate immunity, and immune cytokines expression besides histopathological features of gills of Nile tilapia (Oreochromis niloticus L.) infected with gills monogenetic trematodes (Dactylogyrus sp.). Firstly, the 96-hour lethal concentration 50 (96 h-LC50) of garlic extract (GE) and onion extract (OE) were estimated to be 0.4 g/ L and 3.54 g/ L for GE and OE, respectively. Moreover, the in-vitro anti-parasitic potential for (GE) was found between 0.02 and 0.18 mg/mL and 0.4 to 1.8 mg/mL for OE. For the therapeutic trial, fish (n = 120; body weight: 40–60 g) were randomly distributed into four groups in triplicates (30 fish/group, 10 fish/replicate) for 3 days. Group1 (G1) was not infected or treated and served as control. G2 was infected with Dactylogyrus spp. and not exposed to any treatment. G3, G4 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of OE, respectively. G5, G6 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of GE, respectively. Results No apparent signs or behaviors were noted in the control group. Dactylogyrus spp. infected group suffered from clinical signs as Pale color and damaged tissue. Dactylogyrus spp. infection induced lowering of the hematological (HB, MCH, MCHC and WBCs), and immunological variables (lysozyme, nitric oxide, serum Anti- protease activities, and complement 3). the expression of cytokine genes IL-ß and TNF-α were modulated and improved by treatment with A. sativum and A. cepa extracts. The obtained histopathological alterations of the gills of fish infected with (Dactylogyrus spp.) were hyperplasia leading to fusion of the gill filament, lifting of epithelial tissue, aneurism and edema. The results indecated that G4 and G5 is more regenarated epithelium in compare with the control group. Conclusion A. sativum and A. cepa extracts enhance the blood profile and nonspecific immune parameters, and down-regulated the expression level of (IL-1β and TNF-α).

Abstract In aquaculture, fish are exposed to many stressors, such as climate changes and infectious diseases that affect their performance, immunity, and welfare. Freshwater fish subjected to salt bath become exhausted and stressed. In this experiment, Nile tilapia were exposed to a salt bath at a dose of 30 ppt for 30 min a day. Vitamin C and vitamin E are well-known antioxidants that are used in aquaculture. Fish received dietary nanoparticles of chitosan-vitamin C and chitosan-vitamin E (CCE-NPs) for different periods (7 and 14 days) pre- (G2) and post-salt treatment (G3). In the control fish (G1), cortisol 5.44 µg/dL and glucose 91.67 mg/dL were significantly up-regulated post-salt treatment by 1 h and 24 h, respectively, whereas those (G2) fed CCE-NPs diet had significantly lower values of 4.72 and 3.25 µg/dL; 86.3 and 84.3 mg/dL, respectively. A rapid decrease of glucose 68.3 and 66.3 mg/dL was noticed in those (G2) fed CCE-NPs diet compared to the control 84.67 mg/dL at 48 h post-stress. Regardless of the supplementation period, fish (G2) could partially restore normal food reflex at 48 h (post-salt bath) and fully restored at 72 h compared to 7 days in the control (G1). After 48 h, fish that received dietary CCE-NPs (G2 and G3) restored normal mucus lysozyme levels, whereas the control did not restore pre-treatment values till the seventh day. Mucus antibacterial activity, fish received rapid dietary CCE-NPs (G2) and partially restored average values (pre-salt bath) at 96 h. The salt treatment could provoke gene expression of pro-inflammatory cytokines interleukin (IL-1β) and tumor necrosis (TNF)-α in the head kidney of fish at 24 h post-salt bath to 5.9–8.35 fold-change, respectively, with a rapid decline in fish (G2) the gene expression. Post-salt bath (24 h), the gene expression of glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) was higher in fish (G2) than in the control group (G1) regardless of the supplementation period (7 and 14 days). Bacterial infection S. agalactiae (OL471408), a significantly lower MR was recorded in G2 at 40% and 33.3% compared to the control G1 MR (53.3%), with an RPL of 24.95% and 37.5%. In conclusion, Nile tilapia treated with a 30 ppt salt became more vulnerable to S. agalactiae. Adding CCE-NPs to the Nile tilapia diet for 7- and 14-day pre-salt bath could increase immune and antioxidant-related gene expression to counteract S. agalactiae infection.

Abstract Environmental stressors (such as ammonia) in aquaculture could increase the risk of pathogenicity, posing a more severe threat to farmed fish. The aim of this study was to investigate the effects of ammonia stress on the pathogenicity of Shewanella spp. in Oreochromis niloticus. First, a 96-hour static test was used to determine the median lethal concentration (LC50) of unionized ammonia to Nile tilapia. After 96 h of exposure, the Un-ionized ammonia (UIA) LC50 was estimated to be 4.26 mg/L. Second, an experiment was conducted to test the effect of unionized ammonia stress on the pathogenicity of Shewanella spp. in O. niloticus for 30 days. A study involved 180 fish divided into six groups, with the first group serving as a control. The second group (AMN1/10) and the third group (AMN1/20) were not challenged and were exposed to 1/10 (0.42 mg/L) and 1/20 (0.21 mg/L) of the 96-hour LC50 of UIA, respectively. Then 0.2 mL (0.14 × 105) of Shewanella spp. was intraperitoneally injected into the fourth (SH), fifth (SH + AMN1/10), and sixth (SH + AMN1/20) groups, which were subjected to 0, 1/10 (0.42 mg/L), and 1/20 (0.21 mg/L) of the 96-hour LC50 of UIA, respectively. The survival rate, hematological indices, immunological parameters, and antioxidant activity of the fish significantly decreased when they were exposed to ammonia and Shewanella infection separately or together. Histopathological changes were also observed in the kidney and liver. Furthermore, both individual and combined exposures significantly altered renal and hepatic function, with notable increases in glucose and cortisol levels, as well as in the expression of proinflammatory cytokine genes (TNF-α and IL-1ß). However, the detrimental effects of co-exposure to ammonia stress and Shewanella infection were greater than those of separate exposures. As a result, we may say that increased ammonia concentrations enhance the infection of Shewanella spp. These findings could contribute to a better understanding of Shewanella infection in Nile tilapia.

Abstract To evaluate Tribulus terrestris and Mucuna pruriens for inducing all-male tilapia, mixed-sex Nile tilapia, Oreochromis niloticus, (mean weight 0.025 ± 0.009 g; mean length 1.25 ± 0.012 cm), were given a meal supplemented with either T. terrestris powder (commercial fish feed, 40% crude protein) (TT group), M. pruriens seed extract (MP group), MP + TT (mixed group), 17α-methyl testosterone (MT, control positive), or without supplements (control negative). The MP extracts significantly increased (P

Abstract Edwardsiellosis is a bacterial fish disease that mostly occurs in freshwater farms and is characterized by a high mortality rate. Edwardsiella tarda strain was recovered from 17 fish out of 50 Nile tilapia, which were harboring clinical signs of systemic septicemia. The level of un-ionized ammonia (NH3) in the fish farm’s water was 0.11–0.15 mg/L, which was stressful for the Nile tilapia. Sequencing of the gyrB1 gene confirmed that the isolate was E. tarda JALO4, and it was submitted to NCBI under the accession number PP449014. The isolated E. tarda harbored the virulence gene edw1 AHL-synthase (quorum sensing). In addition, the isolate was sensitive to trimethoprim and sulfamethoxazole mean while it was intermediate to florfenicol. The median lethal dose (LD50) of E. tarda JALO4 was determined to be 1.7 × 105 CFU/mL in Nile tilapia. In the indoor experiment, Nile tilapia (45.05 ± 0.4 g), which received dietary Spirulina platensis (5 and 10 g/kg fish feed), showed optimum growth and feed utilization. Meanwhile, after receiving dietary S. platensis, the fish’s feed conversion ratio (FCR) was significantly enhanced compared to the control, which was 1.94, 1.99, and 2.88, respectively. The expression of immune-related genes interleukin (IL)-1β and tumor necrosis factor (TNF)-α were upsurged in E. tarda-challenged fish with higher intensity in S. platensis groups. Dietary S. platensis at a dose of 10 g/kg fish feed could provide a relative protection level (RPL) of 22.2% Nile tilapia challenged against E. tarda. Nile tilapia experimentally infected E. tarda, drastically altering their behavior: higher operculum movement, low food apprehension, and abnormal swimming dietary S. platensis (10 g/kg fish feed) could rapidly restore normal status. It was concluded that Edwardsiellosis could alter Nile tilapia behavior with a high loss in fish population. Fish received dietary-S. platensis could rapidly restore normal behavior after E. tarda infection. It is recommended the incorporation of S. platensis at doses of 10 g/kg into the Nile tilapia diet to boost their immunity and counteract E. tarda infection.

Abstract The joint impact of tadalafil (Cilais) as a pharmaceutical residue and microplastics on fish is not well comprehended. The current study examined haematological, biochemical, and antioxidant parameters, along with immunohistochemical and histological indications in tilapia (Oreochromis niloticus) after being exposed to tadalafil, polyethylene microplastics (PE-MPs), and their mixtures for 15 days. The fish were distributed into 1st group control group (The fish was maintained in untreated water without any supplements); 2nd group exposed to 10 mg/L PE-MPs;3rd group exposed to 20 mg/l tadalafil (Cilais); 4th group exposed to 20 mg/l tadalafil (Cilais) + 10 mg/LPE-MPs (in triplicate). The levels of creatinine, uric acid, glucose, AST, ALT, and albumin in fish treated with tadalafil alone or in combination with PE-MPs were significantly higher than those in the control group. Fish exposed to PE-MPs, tadalafil, and tadalafil plus PE-MPs showed significantly lower levels of RBCs, Hb, Ht, neutrophils, and lymphocytes compared to the control group. Serum levels of total antioxidant capacity and reduced glutathione (GSH) were notably lowered in fish groups subjected to PE-MPs, tadalafil, and tadalafil + PE-MPs combinations in comparison to the control group. Malondialdehyde (MDA) serum levels were notably elevated in fish groups subjected to PE-MPs, tadalafil, and tadalafil + PE-MPs combinations compared to the control group. The most severe impact was observed in the tadalafil + PE-MPs combination group. Interleukin-6 (IL-6) levels were significantly increased in liver tissues following exposure to both tadalafil and microplastics compared to tissues exposed to only one substance or the control group. Changes in the gills, liver, and renal tissues were seen following exposure to PE-MPs, tadalafil, and tadalafil + PE-MPs combination in comparison to the control group of fish. Ultimately, the mixture of tadalafil and PE-MPs resulted in the most detrimental outcomes. Tadalafil and PE-MPs exhibited showed greater adverse effects, likely due to tadalafil being absorbed onto PE-MPs.

Abstract Background In recent years, anthropogenic activities have released heavy metals and polluted the aquatic environment. This study investigated the ability of the silica-stabilized magnetite (Si-M) nanocomposite materials to dispose of lead nitrate (Pb(NO3)2) toxicity in Nile tilapia and African catfish. Results Preliminary toxicity tests were conducted and determined the median lethal concentration (LC50) of lead nitrate (Pb(NO3)2) to Nile tilapia and African catfish to be 5 mg/l. The sublethal concentration, equivalent to 1/20 of the 96-hour LC50 Pb(NO3)2, was selected for our experiment. Fish of each species were divided into four duplicated groups. The first group served as the control negative group, while the second group (Pb group) was exposed to 0.25 mg/l Pb(NO3)2 (1/20 of the 96-hour LC50). The third group (Si-MNPs) was exposed to silica-stabilized magnetite nanoparticles at a concentration of 1 mg/l, and the fourth group (Pb + Si-MNPs) was exposed simultaneously to Pb(NO3)2 and Si-MNPs at the same concentrations as the second and third groups. Throughout the experimental period, no mortalities or abnormal clinical observations were recorded in any of the treated groups, except for melanosis and abnormal nervous behavior observed in some fish in the Pb group. After three weeks of sublethal exposure, we analyzed hepatorenal indices, oxidative stress parameters, and genotoxicity. Values of alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), urea, and creatinine were significantly higher in the Pb-intoxicated groups compared to the control and Pb + Si-MNPs groups in both fish species. Oxidative stress parameters showed a significant decrease in reduced glutathione (GSH) concentration, along with a significant increase in malondialdehyde (MDA) and protein carbonyl content (PCC) concentrations, as well as DNA fragmentation percentage in the Pb group. However, these values were nearly restored to control levels in the Pb + Si-MNPs groups. High lead accumulation was observed in the liver and gills of the Pb group, with the least accumulation in the muscles of tilapia and catfish in the Pb + Si-MNPs group. Histopathological analysis of tissue samples from Pb-exposed groups of tilapia and catfish revealed brain vacuolation, gill fusion, hyperplasia, and marked hepatocellular and renal necrosis, contrasting with Pb + Si-MNP group, which appeared to have an apparently normal tissue structure. Conclusions Our results demonstrate that Si-MNPs are safe and effective aqueous additives in reducing the toxic effects of Pb (NO3)2 on fish tissue through the lead-chelating ability of Si-MNPs in water before being absorbed by fish.

Background Nile tilapia ( Oreochromis niloticus) is predominant cultured species in aquaculture. However, there is a scarcity of literature regarding relationship between guava and star gooseberry leaf extract and the condition factor. Thus, the present study aims to investigate the effect of guava and star gooseberry leaf extract-supplemented diets on the specific growth rate, length-weight relationship, and condition factor of Nile tilapia. Methods Six hundred and thirty Nile tilapia (8.7±0.4 g) were randomly distributed among twenty-one tanks (30 fish per tank) within a recirculation system. Over a 60-day period, the fish were fed diets supplemented with 5g/Kg and 10g/Kg of guava leaf extract (GLE-5, GLE-10), star gooseberry leaf extract (SGLE-5, SGLE-10), and a mixture of both (MxLE-5, MXLE-10). Subsequently, specific growth rate, length-weight relationship, and condition factor were determined. Results After 60 days, the specific growth rate was significantly higher in all the GLE, SGLE, and MxLE groups compared to the control group. The final lengths and weights differed significantly both in the control group and all the GLE, SGLE, and MxLE groups. The analysis of the regression equation indicated a positive correlation (r = 0.970, 0.977, 0.976, 0.974, 0.974, 0.974, and 0.969) between the length and weight of Nile tilapia in the control group and in all the GLE, SGLE, and MxLE groups. The regression exponent “ b” values in all the GLE, SGLE, and MxLE groups were >3, indicating a positive allometric growth pattern in Nile tilapia compared to the control ( b=2.866), which exhibited a negative allometry. The final condition factor values did not differ significantly in either the control group or any of the plant extract groups. Conclusions Nile tilapia exhibited positive allometric growth patterns and maintained good health when fed with GLE, SGLE, and MxLE groups. Therefore, these plant extracts demonstrate suitability for commercial Nile tilapia production.

Heterophyiasis is a highly endemic disease in the Nile Delta, Egypt, where people consume raw or undercooked Oreochromis niloticus and Mugil cephalus. Birds and rats play a crucial role in fish-borne zoonotic trematode transmission since they serve as natural and experimental hosts. This study aimed to update the epidemiological information, morphological description, molecular identification and gene expression of two distinct heterophyid metacercariae in Giza, Wadi Al-Rayan, and Lake Manzala, Egypt, whereas various heterophyid infections could be expected. The present Centrocestus formosanus, Heterophyes heterophyes, and Heterophyes nocens with accession numbers OR947651.1, OR947700.1, and OR947719.1, respectively, matched with those recorded in the GenBank. Findings of the current investigation indicated that various cytokines like IL-1β, MHC-II, and TNF-α rapidly elevated in the infected pigeon's intestines. Additionally, the infection expanded due to the parasite's ejection from the host and the host's clinical affliction, which induced humoral immune responses. Interestingly, investigation of other trematode species is in extreme demand in terms of zoonoses. We suggest controlling snails, managing migratory birds, and examining and frying fishes to the point when the encysted metacercariae is destroyed. [ABSTRACT FROM AUTHOR]

Cadmium could induce various degrees of harm to aquatic organisms. A 30-day feeding trial was conducted to investigate the effects of cadmium on growth, muscle composition, digestive enzyme activity, gene expression of antioxidants and lipid metabolism in juvenile genetic improvement of farmed tilapia (GIFT, Oreochromis niloticus, Initial weight: 21.36 ± 0.24 g). Four cadmium concentrations of aquaculture water were designed: 0, 0.2, 0.4, and 0.6 mg/L Cd2+. The main results are as follows: Compared with the control group (0 mg/L Cd2+), the weight gain rate (WGR), specific growth rate (SGR), daily growth index (DGI), and spleen index (SI) of juvenile GIFT under cadmium stress were significantly decreased (p< 0.05). The contents of crude protein and crude lipid in muscle were significantly decreased (p< 0.05), and the ash was significantly increased (p< 0.05). The activities of trypsin, lipase, and -amylase in the intestinal were significantly decreased (p< 0.05). The relative expression levels of carnitine palmityl transferase 1 (cpt-1), peroxisome proliferator-activated receptor (ppar ), ppar, hormone-sensitive lipase (hsl), lipoprotein lipase (lpl), malate dehydrogenase (mdh), leptin (lep), fatty acid synthetase (fas), cholesterol response element binding protein 1 (srebp1), squalene cyclooxygenase (sqle), and stearoyl-CoA desaturase (scd) genes in liver were significantly decreased (p< 0.05). The relative expression levels of catalase (cat), superoxide dismutase (sod), glutathione S-transferase (gst), and glutathione peroxidase (gsh-px) genes in the liver were significantly decreased (p< 0.05). In conclusion, exposure to cadmium stress could impact growth,muscle composition, digestive enzyme activity, gene expression of antioxidant and lipid metabolism in juvenile GIFT. [ABSTRACT FROM AUTHOR]

Embryonic temperature has a lasting impact on muscle phenotype in vertebrates, involving complex molecular mechanisms that encompass both protein-coding and non-coding genes. Circular RNAs (circRNAs) are a class of regulatory RNAs that play important roles in various biological processes, but the effect of variable thermal conditions on the circRNA transcriptome and its long-term impact on muscle growth plasticity remains largely unexplored. To fill this knowledge gap, we performed a transcriptomic analysis of circRNAs in fast muscle of Nile tilapia (Oreochromis niloticus) subjected to different embryonic temperatures (24°C, 28°C and 32°C) and then reared at a common temperature (28°C) for 4 months. Nile tilapia embryos exhibited faster development and subsequently higher longterm growth at 32°C compared to those reared at 28°C and 24°C. Nextgeneration sequencing data revealed a total of 5,141 unique circRNAs across all temperature groups, of which 1,604, 1,531, and 1,169 circRNAs were exclusively found in the 24°C, 28°C and 32°C groups, respectively. Among them, circNexn exhibited a 1.7-fold (log2) upregulation in the 24°C group and a 1.3-fold (log2) upregulation in the 32°C group when compared to the 28°C group. Conversely, circTTN and circTTN_;b were downregulated in the 24°C groups compared to their 28°C and 32°C counterparts. Furthermore, these differentially expressed circRNAs were found to have multiple interactions with myomiRs, highlighting their potential as promising candidates for further investigation in the context of muscle growth plasticity. Taken together, our findings provide new insights into the molecular mechanisms that may underlie muscle growth plasticity in response to thermal variation in fish, with important implications in the context of climate change, fisheries and aquaculture. [ABSTRACT FROM AUTHOR]

210Po is one of the most toxic natural radionuclides. This isotope's characteristics and radiological hazard assessment have been concerned in different objects. In this study, the 210Po activities were determined in different tilapia organs/parts of 20 sample groups by alpha spectrometry. The 210Po activities in muscle, bone, intestine organs, and stomach contents unevenly distributed with a wide range from 0.5 ± 0.2 to 2.8 ± 0.4 and 1.4 ± 0.2 Bq·kg−1 wet.wt on average, from 0.6 ± 0.3 to 6.3 ± 0.7 and 3.5 ± 0.4 Bq·kg−1 wet.wt on average, from 46.3 ± 2.9 to 263 ± 9.7 and 115 ± 6 Bq·kg−1 wet.wt on average, and 20.9 ± 1.2 to 800 ± 29 and 197 ± 9 Bq·kg−1 wet.wt on average, respectively. The average 210Po activities in different parts of tilapia trend in order of CMuscle < CBone < CIntestine < CStomach contents. Insignificant correlations were observed between 210Po activities in tilapia organs with their total fish mass. The result could depend on feeding types, diet, different nutrient levels, metabolism, and excretion of 210Po in different ages. The concentration ratios (CRs) of tilapia muscle and bone organs were recorded with low values, while it was far greater than the CRs for the intestine organ. Annual committed effective doses contributing from 210Po concentration due to tilapia fish consumption were within the allowable limits for muscle and bone organs, while those values for intestine organs were far higher than the allowable limit value (assuming similar amount consumption of 30 kg·year−1 for each organ). The Erica tool was used to estimate the dose and risk to tilapia from 210Po exposure. Based on the calculated results, it can be seen that there was insignificant concern for tilapia due to ionizing radiation in the study area. [ABSTRACT FROM AUTHOR]

Newly synthesized vaccines prepared from formalin-killed bacteria Streptococcus pyogenes were investigated in the current study to evaluate the effectiveness of the newly synthesized vaccine as well as their safety by injected intraperitoneal. The study involved several steps 1st step is the preparation of the vaccine followed by the 2nd step: Evaluate the effectiveness and vaccine safety against pathogenic S. pyogenes through 4 different groups including control (Group I). Group II (Bacterial, infected group), Group III (Vaccine), and the Last group was the challenged group after the vaccination (Vacc + Bac). Different Immunological and biochemical parameters were measured in addition to hematological and histopathological examinations. For example, oxidative/antioxidants, inflammatory biomarkers, fragmentation and cell damage, and finally the histopathological study. The current study showed an increase in all oxidative, inflammatory, and cell damage (DNA fragmentation assays), additionally markedly elevation in histopathological cell damage in the infected group (Group II) compared with the control group. The vaccine and challenged after vaccination group (vaccine + Bacteria), showed great improvement in oxidative biomarkers (LPO) and an increase in antioxidants biomarkers (GSH, SOD, GST, DPPH, ABTS, GR and GPx), Also the inflammation and histopathological examination. The newly synthesized vaccine improved the resistance of Oreochromis niloticus and can be used as a preventive therapy agent for pathogenic bacteria S. pyogenes. [ABSTRACT FROM AUTHOR]

Probiotics are becoming increasingly popular as eco-friendly alternatives in aquaculture. However, there is limited research on their impacts on the reproductive efficiency of Red Tilapia (Oreochromis niloticus x O. mossambicus) broodstock. Therefore, this experiment aimed to explore the combined effects of selective probiotics Bacillus subtilis and B. licheniformis (BSL; 1:1) added to water on blood hematology, serum metabolites, gonadal histology, reproductive performance, and reproductive associated genes in Red Tilapia broodstock. Tilapia broodfish weighing 140–160 g were stocked in four treatment groups: control (T0), and the other three groups were added different levels of BSL to the water as follows: T1 (0.01 g/m3), T2 (0.02 g/m3), and T3 (0.03 g/m3), respectively. Results indicate that BSL administration significantly improved RBCs, hemoglobin, hematocrit, MCH, and MCHC, with the highest improvement seen in the T3 group (P < 0.05). BSL added to the fish water significantly enhanced serum protein fractions (total protein, albumin, and globulins), while AST, ALT, ALP, creatinine, uric acid, and glucose were significantly diminished in a dose-dependent way (P < 0.05). Adding 0.02–0.03 g/ m3 of BSL resulted in higher antioxidant status (superoxide dismutase and catalase) compared to other groups (P < 0.05). Testosterone levels were higher in T3 than in other groups (P < 0.05). All female hormones (LH, FSH, estradiol, and progesterone) were substantially augmented by the addition of BSL. Additionally, the BSL groups exhibited higher GSI, HSI, VSI (male only), egg diameter (mm), mean number of fry/fish, and mean fry weight (g) compared to the control group (P < 0.05). Expression of reproductive-associated genes (vasa, nanos1a, nanos2, dnd1, pum1, AMH, and vtg) were significantly up-regulated in the gonads of fish in the 0.03 g/m3 treatment. The histological gonadal structure exhibited that BSL improved gonad maturation in both genders of Tilapia fish. Overall, adding a mixture of B. subtilis and B. licheniformis (0.03 g/m3 water) can accelerate reproductive performance in Red Tilapia through up-regulation of reproductive genes and enhance the health profile. [ABSTRACT FROM AUTHOR]

【Objective】The deposition and decomposition of solid particles in aquaculture wastewater will lead to the deterioration of aquaculture water and affect the health of fish. The study was conducted to understand the sedimentation rule of solid particles in aquaculture wastewater of Nile tilapia (Oreochromis niloticus) and its influence on the aquaculture water body, with an aim to provide a theoretical basis for the research and development and design of aquaculture wastewater treatment system.【Method】 The aquaculture wastewater of Nile tilapia pond was treated by static sedimentation. Samples of aquaculture wastewater at different depths were collected at different sedimentation times, and the particle size distribution, soluble organic components and water quality indexes of aquaculture wastewater were analyzed.【Result】Static sedimentation had no significant effect on the quality of aquaculture wastewater (P>0.05), and only reduced the mass concentrations of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) in aquaculture wastewater surface. Suspended solids and algae in aquaculture wastewater could be separated by static sedimentation (P<0.05). After static sedimentation for 5.0 h, the TSS, chlorophyll a mass concentration, turbidity and chromaticity of two-meter-high water decreased by 3 854 mg/L, 42 mg/L, 0.23 NTU and 309 degrees respectively, and the TSS and chlorophyll a mass concentrations in aquaculture water decreased with the extension of sedimentation time. The results of particle size distribution showed that the settleable particles larger than 100 μm could be effectively separated by static sedimentation, but the fine particles lower than 30 μm could not be separated. The sedimentation velocity of solid particles was related to its particle size distribution range and mass concentration. The sedimentation velocity of solid particles decreased with the decrease of particle size distribution range and the increase of mass concentration. The results of three-dimensional fluorescence spectrum showed that the soluble organic compounds in the wastewater of Nile tilapia were mainly fulvic acid-like, and the soluble organic components in the wastewater could not be completely changed by static sedimentation.【Conclusion】Short time static sedimentation can effectively remove settleable particles in aquaculture wastewater, and the mass concentrations of TSS and chlorophyll a decrease with the extension of sedimentation time. However, static sedimentation cannot completely change the soluble organic components in the wastewater, nor can it significantly reduce the mass concentrations of nitrogen, phosphorus and other pollutants in aquaculture wastewater. [ABSTRACT FROM AUTHOR]

A 60-feeding day was performed to explore the potential influence of dietary intervention with a mixture of oligosaccharides and β-glucan (OLG) on growth, feed utilization, body composition, biochemical parameters, growth-related genes, and resistance to Streptococcus iniae infection of Nile tilapia (Oreochromis niloticus). Fish (n = 360, average weight 24 ± 0.2 g) were allotted into four experimental groups. Fish were received basal diets and inclusion of a mixture of oligosaccharides and β-glucan (1:1) at various levels 0 (OLG0), 1 (OLG1), 1.5 (OLG1.5), and 2 (OLG2) g/kg feed for 60 days. Fish were erratically scattered into tanks at a density of 30 fish/tank and the experiment was conducted in triplicates. All OLG groups had better final body weight, feed conversation ratio (FCR), and body weight gain and percentages (p < 0.05), while the feed intake did not change (p > 0.05). Fish fed with 1.5 or 2 g of OLG exhibited higher SGR, survival rates, and ADG than the OLG1 and OLG0 groups. All OLG-treated groups significantly improved the fish body composition in dose-dependent manner (p < 0.05). Protein fractions (total protein, albumin, and globulins) were significantly improved, and liver enzymes were significantly decreased (AST, ALT, and ALP) in all-OLG supplemented in dose-dependent manner (p < 0.05). Both OLG1.5 and OLG2 groups had lower values of MDA and higher levels of lysosome activity compared to those in other groups. Fish in the OLG2 group recorded the best results for antioxidant biomarkers GPx, IgM, CAT, and SOD compared to those in other groups. The expressions of GH and IGF-1 genes were significantly up-regulated by dietary inclusion in dose-dependent way (p < 0.05). Fish that fed OLG exhibited higher survival rate against S. iniae infection compared to the control one. Overall, this research suggested a suitable integration level of β-glucan and oligosaccharides that could enhance growth and feed parameters, body composition, blood profile, serum metabolites, growth-associated genes, and resistance to S. iniae infection of Nile tilapia, with an ideal dose of 1.5 and 2 g/kg feed. [ABSTRACT FROM AUTHOR]

This study investigated the effects of different dietary levels of Triphala fruit powder on the growth performance, histology, serum parameters, gene expression indicators, and survival of Nile tilapia (Oreochromis niloticus) fingerlings against Saprolegnia ferax infection. The fish were fed with either a control diet (without Triphala fruit powder addition) or three experimental diets including 1, 2, and 3% of TFP over a 60-day period. Two hundred and forty healthy fish (28.0 ± 0.2 g) were stocked in 12 tanks, 20 fish per tank. Dietary TFP supplementation significantly improved growth performance and feed efficiency to the un-treated group (P < 0.05). All Triphala fruit powder dietary groups had a significant higher amylase activity and lower levels of ALT, AST, and cholesterol than the control group (P < 0.05). The Triphala fruit powder treatment (3%) resulted in a significant increase in packed cell volume, red blood cell count, haemoglobin, and monocyte values compared to other groups (P < 0.05). The study reported significant (P < 0.05) improvements in immune response and increased levels of haemoglobin, white and red blood cells, albumin, globulin, and total protein for the Triphala dietary groups. In all Triphala dietary groups, the mRNA expression levels of the growth-related (growth hormone (GH) and insulin-like growth factor 1 (IGF-1)) and immune-related genes (cc-chemokine, intereluekin-1β (IL-1β), and intereluekin-8 (IL-8)) were significantly (P < 0.05) upregulated compared to the control groups. After exposure to Saprolegnia ferax infection, the control group exhibited a higher mortality rate (up to 75%) than the Triphala-treated groups. In conclusion, this study demonstrated that dietary inclusion of Triphala at an optimal level of 3% improved the growth performance and immune response of Nile tilapia (Oreochromis niloticus) fingerlings. [ABSTRACT FROM AUTHOR]

Due to limited data on the pathogenicity of Prohemistomum vivax (P. vivax) and its impacts on fish health, this study aimed to determine the morphological, molecular characteristics, pathogenicity, and histopathological alterations in fish infected with P. vivax. Eight hundred (800) Nile tilapia (Oreochromis niloticus) were collected from various farms in Kafr El Sheikh Governorate. The fish were examined for encysted metacercariae (EMC) in different organs. Tissue specimens were collected and underwent histopathological analysis, expression of stress-related genes, and genetic characterization by sequencing of the internal transcribed spacer 2 (ITS2). P. vivax metacercariae were oval to round in shape and were collected from various organs including the muscle, skin, eyes, intestine, liver, kidney, and gills of infected O. niloticus. Sequencing and phylogenetic analysis of the ITS2 region revealed a 507-bp fragment, confirming parasite identity and matching within the same clade as other P. vivax isolates. Infected fish displayed abdominal hydropsy, skin darkening, and emaciation. P. vivax encysted metacercariae were detected during the study period in 620/800 fish, with an overall prevalence of 77.5%. The seasonal prevalence was 95% in summer, 85% in spring, 55% in autumn, and 75% in winter. The intensity of infection was 1–40 cysts per microscopic field. Histopathological examination of muscles revealed parasitic cysts embedded within muscle fibers, causing severe degeneration and necrosis. Upregulation of cytochrome P450 (cpy1a1), heat shock protein 70 (hsp-70), and tumor suppressor p53 (p53) was recorded in both liver and muscle samples of infected tilapia compared to controls. This indicates activation of detoxification, cellular stress, and apoptotic pathways in response to P. vivax infection. There is limited data available on the pathogenicity of P. vivax and its impacts on fish health; thus, this study provides key insights into the morphology, pathogenicity, and histopathological impacts of P. vivax in Nile tilapia. [ABSTRACT FROM AUTHOR]

Fungal diseases in fish cause economic losses all over the world, and knowledge about them is scarce and outdated in Aswan Governorate, Egypt, making interpretation, prevention, and treatment difficult. The necessity to find a fungicide that is natural, environmentally friendly, and does not emerge drug resistance is a must. Therefore, the current study aimed to isolate and diagnose fungal infection in farmed Oreochromis niloticus, causing mortalities, in Aswan Governorate. During 2021, 200 fresh O. niloticus samples were collected from the Sahary Fish Hatchery and Aswan General Authority for Fish Resources Development fish farm. Some fish showed hemorrhagic lesions all over the body, detachment of scales, and fin erosion. Collected tissue samples were cultured on potato dextrose agar and Sabouraud dextrose agar for phenotypic characterization. Macroscopic and microscopic analyses were used to identify the isolated fungi. A total of 18 fungal species and two varieties appertaining to ten fungal genera were recovered from 48 samples out of 200 examined O. niloticus (24%), with Aspergillus flavus being the most prevalent at a rate of 25.6%. The isolated A. flavus was proven to be pathogenic to farmed O. niloticus, as by experimental infection. The natural herb Persicaria salicifolia had an LC50 value of 41.68 mg/l in exposed O. niloticus and was used to treat A. flavus-infected O. niloticus. It can be concluded that A. flavus poses a major hazard to O. niloticus aquaculture and can be treated with 40 mg/kg in feed or 20 mg/l in water of P. salicifolia for 6 days. [ABSTRACT FROM AUTHOR]

The biofloc system is a sustainable alternative for intensifying aquaculture production; however, in this production system there may be an excess of solids present in the water. These solids are rich in nutrients that, when in excess, can harm the fish in addition to contributing to environmental pollution, so the use of these solids in fish feeding can become an alternative to reuse this residue. The aim of this study was to evaluate the inclusion of biofloc meal (BM) in tilapia diets in levels of 0, 4, 8, 12, and 16%. Performance parameters, somatic indices, centesimal proximate composition, and hematological and oxidative parameters were evaluated. For the growth parameters, there was a reduction in growth with the inclusion of 16% when compared to the 4% level. For the centesimal composition, there was a difference for the crude protein content in the carcass, where the fish fed with 16% BM had higher protein content in the carcass when compared to the other levels. Regarding oxidative parameters, the results indicated that even the inclusion of 4% BM led to improvements in antioxidant enzyme activity. Based on the findings of this study, it is recommended to add small levels of BM (4% inclusion) to tilapia diets. It should be noted that higher levels of BM may negatively impact production, and further investigations focusing on lower inclusion levels are warranted to provide a comprehensive understanding of the optimal dosage. [ABSTRACT FROM AUTHOR]

The effects of cyclical feeding restriction (3, 4, 5, 6, and 7 days of feeding per week) on the performance of juvenile Nile tilapia (Oreochromis niloticus) in a biofloc technology system (BFT) were evaluated in this study for 77 days. Fifteen experimental units (400L) with temperature control (mean 28.2 °C) randomly distributed 1500 fish (0.42 ± 0.02 g). Fish were fed commercial feed (46.7 g of crude protein and 4475.5 kcal kg−1 of gross energy) up to satiation. Feeding cycles with different restrictions (p < 0.05) influenced animal growth but not survival and final density (p > 0.05), which remained around 94% and 235 fish.m−3, respectively. Juveniles fed 6 days a week showed 1.25 of feeding efficiency, while animals fed 3 days a week (more restricted) showed hyperphagia but did not exhibit compensatory growth. Changes in the morphology of hepatocytes (presence of vacuoles, displacement of the nucleus to the periphery, and fatty degeneration) were observed with an increase in feeding days, and a high degree of hepatic steatosis (p < 0.05). Water quality parameters remained within acceptable limits for the species and system operation. Feeding regimes influenced the characteristics of bioflocs (total suspended solids and porosity) and the abundance of microorganisms (p < 0.05). Nutritionally, less restricted diets (6 and 7 days of feeding per week) produced more protein (38.3 and 40.6% CP) and energy bioflocs (2252.8 and 2313 kcal.kg−1) (p < 0.05), while protein, lipid, and body energy were significantly lower (p < 0.05) with the more restricted diet. The composition of microorganisms was influenced by the feeding regimes (p < 0.05). Results demonstrated that the occurrence of total compensatory growth (6 days of feeding per week) represents an economic advantage with a reduction of 26.8% of feed and greater profitability in the unitary commercialization of tilapia juveniles. [ABSTRACT FROM AUTHOR]

Haematococcus pluvialis is a microalga that can reduce the levels of inorganic and organic components in effluents, in addition to production of the high-value carotenoid astaxanthin. The present study proposed an integrated system for the simultaneous treatment of effluent from a Nile tilapia recirculation system and astaxanthin production using the microalga H. pluvialis. Cultures were developed in 2 L bottles, with freshwater previously treated and enriched with a modified Bold's Basal Medium (BBM). The experiment was carried out on a laboratory scale using a completely randomized experimental design with five treatments: control (100% BBM), E25 (25% Nile tilapia effluent + 75% BBM), E50 (50% Nile tilapia effluent + 50% BBM), E75 (75% Nile tilapia effluent + 25% BBM), E100 (100% Nile tilapia effluent), with three replicates for each condition. H. pluvialis could grow in all proportions of effluent from Nile tilapia cultivation. The use of effluent as culture medium (E100), despite having lower cell density and biomass, resulted in biomass with high astaxanthin content (10 mg g−1) and antioxidant activity (89% inhibition of DPPH radicals). Meanwhile, this integrated system significantly contributed to the effluent remediation (98% N and 91% P removal). H. pluvialis can be used for cost-effective treatment of aquaculture effluent with simultaneous production of astaxanthin, with potential application as aquafeed, in a holistic bioeconomy approach. [ABSTRACT FROM AUTHOR]

Water temperature is a major environmental factor affecting fish activity, physiology, behavior, and growth. Alpha lipoic acid (ALA) has garnered much attention lately as an aqua feed supplement because of its antioxidant effects. Thus, this study aimed to assess the effect of dietary ALA on performance, hematological and immunological indices, behavior and oxidative stress, apoptosis, and genetic inflammation in Oreochromis niloticus following 60 days of cold stress. Two hundred forty fish were divided into four groups (15 fish/replicate, N = 60 fish/group). The control (CNT) and ALA groups were reared at 25 °C and fed a basal diet without any supplementation or a basal diet containing 600 mg ALA/kg diet, respectively. The cold water-stressed group (CWS) and ALA + CWS groups were reared at 18 °C and fed basal and basal diets containing ALA, respectively. The results revealed that dietary ALA supplementation significantly improved feed utilization and growth in fish. ALA also mitigated CWS-induced microcytic hypochromic anemia and hyperlipidemia. Moreover, ALA supplementation considerably enhanced the antioxidant status and boosted intestinal α amylase, lipase, protease, and serum acetylcholinesterase activity of CWS-exposed fish. Besides, ALA supplementation significantly reversed CWS-induced upregulation of proinflammatory genes, pro-apoptotic genes, heat shock protein, and proliferating cell nuclear antigen or downregulation of superoxide dismutase and catalase gene expressions in liver and spleen tissues. Furthermore, ALA supplementation reduced CWS-induced histopathological alterations in fish liver, spleen, and intestine. We can conclude that ALA (600 mg/kg diet) could be recommended as an aqua feed supplement to boost growth, antioxidant capacity, and immunity and attenuate inflammatory and apoptotic reactions of fish reared under CWS-induced. [ABSTRACT FROM AUTHOR]

Lead (Pb) is a common heavy metal, which negatively influences the health and performance of aquatic organisms. The aquatic pollution with Pb is increasing day after day due to the increase in human activities, agricultural, and mining activities among others. Lead was regarded as oxidative stressor causing mutagenic and physiological disorders in aquatic animals. Hence, the current perspective assessed the promoting effects of dietary mixture of rosemary plus cinnamon (R + C) intervention on growth, hemato-biochemical, and hepatic oxidative biomarkers in Nile tilapia (Oreochromis niloticus) exposed to a sub-lethal dose of lead nitrate (7.94 mg Pb/L) for 60 days. Fish were distributed into four equal groups; T1 was kept as a control group, T2 was fed on 10 g R + C/kg feed, and T3 and T4 were fed on the control diet and 10 g R + C/kg feed, respectively, along with lead nitrate exposure. Findings of the present study indicated that, upon exposure to Pb (T3), growth, hemato-biochemical, and immune indices in Nile tilapia were notably reduced compared with that of the control group (T1). Meanwhile, stress (blood glucose, cortisol, total cholesterol, lactate dehydrogenase, alanine and aspartate aminotransferase, and alkaline phosphatase), hepatic oxidative stress (superoxide dismutase, catalase, and glutathione peroxidase) biomarkers, and DNA fragmentation percentage were significantly augmented in T3 vs T1. Additionally, exposing fish to lead nitrate caused immune suppression compared with the control group (T3 vs T1). On the other hand, the dietary supplementation of R + C mix to Nile tilapia (T2) enhanced its growth performance, antioxidant, and immune status. Feeding Pb-intoxicated Nile tilapia on R + C mix (T4) mitigated the oxidative damage and immune suppression induced by lead nitrate exposure compared with T3. Based on the present study outcomes, we opine that feeding Nile tilapia with rosemary plus cinnamon mixture (10 g/kg feed) has protective effects against lead nitrate-induced stress, physiological alterations, and oxidative damage. [ABSTRACT FROM AUTHOR]

Iron (Fe) is a crucial mineral for the health of fish. The investigation explored the effects of two different sources of iron (organic and inorganic) and two levels (60 and 85 mg/kg) of Fe on the innate immunity, antioxidant capacity, and hematological responses of Nile tilapia. Fish with an average weight of 16.57 ± 2.25 g were fed three times a day for a duration of seven weeks. A total of 400 fish were distributed among 20 tanks, each with a capacity of 240 L and housing 20 fish. The experiment comprised five treatments, and the experimental design employed was a completely randomized design, which included the following treatments: a basal diet (BD) with no addition of Fe in the premix, 60 mg/kg Inorganic Fe, 60 mg/kg Organic Fe, 85 mg/kg Inorganic Fe, and 85 mg/kg Organic Fe. The results indicated that the use of organic Fe significantly improved the hematocrit levels and mean corpuscular hemoglobin. Conversely, the values of lysozyme decreased in fish that were fed with the organic Fe source. However, the hemolytic activity of the complement system and the production of the superoxide anion test exhibited an increase with the use of organic Fe. Furthermore, the fish that were fed with the 85 mg/kg organic diet demonstrated superior antioxidant responses. In conclusion, the inclusion of organic Fe at a concentration of 85 mg/kg was found to be more efficient for the growth of juvenile Nile tilapia. [ABSTRACT FROM AUTHOR]

Antibiotics are crucial in the control of bacterial infections on fish farms. However, the influence of licensed antibiotics on DNA damage, histological changes, and protein differentiation in some farmed fish species is unidentified. The current study aimed to investigate the effect of therapeutic (80 mg/kg body weight/day) and high doses (160 mg/kg body weight/day) of oxytetracycline (OTC) on some biological indices, protein differentiation, histological changes, and DNA damage in Oreochromis niloticus (n = 360; 40 ± 3.5 g) and the potential positive effects of dietary ascorbic acid (AA) and whether it is capable of reducing the deleterious impacts of OTC and working synergistically to increase fish disease resistance and decrease morbidity and mortality rates. In the current study, fish were fed diets with or without OTC (80 or 160 mg/kg body weight/day) and AA (100 mg/kg diet/day) for 28 days, followed by a bacterial stress test with two different virulent strains for 14 days. Treatments include CTR (control; without additives), AA, OTC80, OTC160, OTC80 + AA, and OTC160 + AA. The results revealed that the AA group had the best antioxidative (significant increase in SOD, CAT, and GPx) and immunomodulatory effects (an increase in IgM, nitroblue tetrazolium, and total leucocytic count). Furthermore, the hematological parameters, immune indices (NBT), and antioxidant enzymes were significantly reduced by OTC160 (p ≤ 0.05). The results also showed that OTC160 notably augmented the activity of liver (ALT, AST, and LDH) and kidney (creatinine and urea) damage markers (p ≤ 0.05). OTC160 revealed considerable hepatic and renal tissue damage and significantly higher hepatocyte DNA damage. Pathological changes and DNA damage were directly correlated to the dosage of OTC exposure, where they were more severe in OTC160. OTC80 showed insignificant changes in most parameters. Compared to CTR, the inclusion of AA in the O. niloticus diet significantly restored the biological indices, histological changes, and DNA damage in OTC-treated groups. The morbidity and mortality percentages after bacterial challenge were significantly lower in the OTC80 + AA group, followed by the OTC160 + AA group than in the CTR. These results corroborate the use of AA as a potent antioxidant and immune stimulant and a potential co-adjuvant to OTC in the diet of O. niloticus to reach optimal resistance to disease. [ABSTRACT FROM AUTHOR]

Survival of probiotics in processed feed can be affected not only by feed processing techniques but also by factors such as storage and gastrointestinal transit of ingested feed. This study investigates the effect of free and spray-dried Bacillus subtilis (BS) in oat β-glucan microcapsules on growth performance, hematology, intestinal microbiota, histology, and immunology of Nile tilapia, Oreochromis niloticus. A total of 400 tilapia were randomly stocked into 25 aquaria in a randomized experimental design and fed one of the following diets: (C) control diet (without synbiotics); (0.1%S) 1g kg−1 diet of unloaded microcapsules and 2.7 × 109 of free BS CFU kg−1 diet; (0.2%S) 2 g kg−1 diet of unloaded microcapsules and 5.4 × 109 of free BS CFU kg−1 diet; (0.1%SM) 1g of microcapsules loaded with 2.7 × 109 BS CFU kg−1 diet; and (0.2%SM) 2g of microcapsules loaded with 5.4 × 109 BS CFU kg−1 diet. After a 60-day feeding trial, fish fed 0.2%SM showed the highest growth performance and best feed utilization compared to fish fed free probiotics and control diet. Intestinal villi were longer, and the submucosa layer was thicker in fish fed both free and microencapsulated probiotics than the control group. Fusobacteriota, Firmicutes, and Bacteroidota were the dominant phyla across all samples accounting for more than 90% of the gut microbiota. No differences were registered in hematological parameters. Phagocytic activity was enhanced in fish fed both 0.2%S and 0.2%SM diets. Microencapsulation has the potential to protect B. subtilis and may constitute a valuable approach for enhancing the viability of probiotics as additives for fish feeds. [ABSTRACT FROM AUTHOR]

Probiotic production in commercial culture media is expensive, so, it is necessary to design culture media based on "low-cost" components like agro-industrial by-products. Therefore, this study aimed to design an agro-industrial by-product-based culture media using whey, sugarcane molasses, and palm kernel cake as components to produce Lactococcus lactis A12, Priestia megaterium M4, and Priestia sp. M10 isolated from Nile tilapia (Oreochromis niloticus) associated gut microbiota. Higher bacterial concentrations were achieved at high whey concentrations and low concentrations of sugarcane molasses and palm kernel cake (PKC) using agitation. The optimal conditions were whey, 3.84% w/v; sugarcane molasses, 7.39% w/v; PKC, 0.77% w/v; and agitation speed, 75 RPM. Bacterial growth under optimal conditions was compared to that in commercial Brain–Heart Infusion (BHI) broth. L. lactis A12 showed similar growth in the optimal media and BHI. The estimated cost of the culture media based on component prices was USD $ 3.01/L, which is 86.93% lower than BHI broth (USD $ 23.04/L). It was possible to design a "low-cost agro-industrial by-product-based culture media to produce L. lactis A12 and the two Priestia species under monoculture conditions. [ABSTRACT FROM AUTHOR]

In mammals, glial cell derived neurotrophic factor (GDNF) plays a critical role in the self-renewal and maintenance of spermatogonial stem cells (SSCs) in testis and oogenesis in ovary, whilst retinoic acid (RA), the key factor of meiosis initiation, can downregulate its expression. Unlike mammals, two Gdnf replication genes are widely present in teleost fishes, however, our understanding of them is still poor. In the present study, two paralogous gdnf from Nile tilapia (Oreochromis niloticus), namely as Ongdnfa and Ongdnfb , were characterized, and then their cellular expression profiles in testis and ovary and responsiveness to RA treatment at the tissue and cellular levels were investigated. In phylogenetic tree, the Gdnfa and Gdnfb from teleost fishes were clustered into two different subclasses, respectively, and then clustered with the homologs from cartilaginous fish and tetrapods, suggesting that OnGdnfa and OnGdnfb are orthologous to GDNF and paralogous to each other. Ongdnfa is expressed in Sertoli cells and Leydig cells in testis and oocytes in ovary. The expression pattern of Ongdnfb is similar to Ongdnfa. In the ex vivo testicular organ culture, RA down-regulated the expression of Ongdnfa , whereas up-regulated the expression of Ongdnfb (P < 0.05), suggesting that they have differential responsiveness to RA signaling. RA treatment of the cultured cells derived from adult Nile tilapia testis which have the expression of RA receptors (RAR), Ongdnfa and Ongdnfb further confirmed the above result. Collectively, our study suggests that Ongdnfa and Ongdnfb have non-germline expression patterns in testis and germline expression patterns in ovary; furthermore, they have differential responsiveness to RA signaling, implying that they might have differential biological functions. This study broadens and enriches our understanding of fish GDNF homologs and lays foundation for the study of their biological functions in the future. • Two paralogous gdnf (Ongdnfa and Ongdnfb) were characterized from Nile tilapia. • Ongdnfa and Ongdnfb had non-germline expressions in testis. • Ongdnfa and Ongdnfb had germline expressions in ovary. • Ongdnfa and Ongdnfb had differential responsiveness to RA treatment. [ABSTRACT FROM AUTHOR]

The article discusses the importance of sustainable aquaculture and the development of immunonutritional approaches to enhance fish performance, health, and welfare. The special issue focuses on novel feeds and functional ingredients that can improve growth, immunity, and disease resistance in various commercially important aquatic species. The studies highlight the potential of alternative protein and lipid sources, as well as the use of bioactive compounds and probiotics, to promote fish health and reduce the need for antibiotics. Continued research and collaboration are necessary to scale up these innovations and meet the global demand for seafood while minimizing the ecological impact of aquaculture. [Extracted from the article]

Simple Summary: Cadmium is a toxic non-essential transition metal and poses significant risks to diverse organisms residing in aquatic ecosystems. Cadmium has the potential to build up in various levels of organisms within a food chain, which may pose a risk to human health as it progresses through the trophic levels. The presence of abundant hydroxyl and amino groups in chitosan enables effective adsorption and binding of heavy metal ions, thereby facilitating the removal of diverse heavy metal pollutants and water quality purification. In this study, five groups of juvenile tilapias (initial body weight 21.21 ± 0.24 g) were fed five diets with different levels (0%, 0.5%, 1.0%, 1.5%, and 2.0%) of chitosan supplementation for 60 days under cadmium stress (0.2 mg/L Cd2+). The findings suggested that the growth performance, serum biochemical indices, antioxidant capacity, immune response, inflammatory response, and expression of relevant genes in juvenile GIFT could be positively affected by dietary chitosan under cadmium stress. The objective of this study was to examine the effects of varying levels of dietary chitosan supplementation on mitigating cadmium stress and its influence on growth performance, serum biochemical indices, antioxidant capacity, immune response, inflammatory response, and the expression of related genes in juvenile Genetically Improved Farmed Tilapia (GIFT, Oreochromis niloticus). Five groups of juvenile tilapias (initial body weight 21.21 ± 0.24 g) were fed five diets with different levels (0%, 0.5%, 1.0%, 1.5%, and 2.0%) of chitosan supplementation for 60 days under cadmium stress (0.2 mg/L Cd2+). The findings indicated that, compared with the 0% chitosan group, dietary chitosan could significantly increase (p < 0.05) the final weight (Wf), weight gain rate (WGR), specific growth rate (SGR), daily growth index (DGI), and condition factor (CF), while the feed conversion ratio (FCR) expressed the opposite trend in juvenile GIFT. Dietary chitosan could significantly increase (p < 0.05) the activities (contents) of cholinesterase (CHE), albumin (ALB), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), acid phosphatase (ACP), and lysozyme (LZM), while glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), and complement 3 (C3) in the serum of juvenile GIFT expressed the opposite trend. Dietary chitosan could significantly increase (p < 0.05) the activities of superoxide dismutase (SOD) and catalase (CAT) and significantly decrease (p < 0.05) the activities (contents) of glutathione S-transferase (GST), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) in the serum of juvenile GIFT. Dietary chitosan could significantly increase (p < 0.05) the activities (contents) of CAT, GST, GSH-Px, and total antioxidant capacity (T-AOC) and significantly decrease (p < 0.05) the contents of MDA in the liver of juvenile GIFT. Dietary chitosan could significantly increase (p < 0.05) the activities (contents) of SOD, GSH-Px, T-AOC, Na+-K+-ATPase, and Ca2+-ATPase and significantly decrease (p < 0.05) the activities (contents) of CAT, GST, and MDA in the gills of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of cat, sod, gst, and gsh-px in the liver of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of interferon-γ (inf-γ) in the gills and spleen and significantly down-regulate (p < 0.05) the gene expression of inf-γ in the liver and head kidney of juvenile GIFT. Dietary chitosan could significantly down-regulate (p < 0.05) the gene expression of interleukin-6 (il-6), il-8, and tumor necrosis factor-α (tnf-α) in the liver, gills, head kidney, and spleen of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of il-10 in the liver, gills, head kidney, and spleen of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of transforming growth factor-β (tgf-β) in the liver and significantly down-regulate (p < 0.05) the gene expression of tgf-β in the head kidney and spleen of juvenile GIFT. In conclusion, dietary chitosan could mitigate the impact of cadmium stress on growth performance, serum biochemical indices, antioxidant capacity, immune response, inflammatory response, and related gene expression in juvenile GIFT. According to the analysis of second-order polynomial regression, it was found that the optimal dietary chitosan levels in juvenile GIFT was approximately 1.42% to 1.45%, based on its impact on Wf, WGR, SGR, and DGI. [ABSTRACT FROM AUTHOR]

Bacterial illness causes detrimental impacts on fish health and survival and finally economic losses for the aquaculture industry. Antibiotic medication causes microbial resistance, so alternative control strategies should be applied. In this work, we investigated the probiotic-medicated diet as an alternative control approach for antibiotics in treating Vibrio cholerae infection in Nile tilapia (Oreochromis niloticus). One hundred eighty fish (50 ± 2.5 g Mean ± SD) were allocated into six groups in glass aquariums (96 L) in triplicate for 10 days. Groups 1 (G1), G2, and G 3 were intraperitoneally (IP) injected with 0.5 mL sterilized tryptic soy broth and fed on a basal diet, basal diet contained B. subtilis (BS) (1 × 10 5 CFU/ kg-1 diet), and basal diet contained trimethoprim-sulfamethoxazole (TMP-SMX) (1.5 g/kg-1 diet), respectively. Additionally, G4, G5, and G6 were IP challenged with 0.5 mL of V. cholerae (1.5 × 107 CFU) and received the same feeding regime as G 1 to 3, respectively. The results exhibited that the V. cholera-infected fish exhibited skin hemorrhage, fin rot, and the lowest survival (63.33%). Additionally, lowered immune-antioxidant biomarkers (white blood cells count, serum bactericidal activity, phagocytic activity, phagocytic index, and lysozymes) with higher lipid peroxidation marker (malondialdehyde) were consequences of V. cholerae infection. Noteworthy, fish-fed therapeutic diets fortified with BS and TMP-SMX showed a substantial amelioration in the clinical signs and survival. The BS diet significantly improved (P < 0.05) the immune-antioxidant indices of the infected fish compared to the TMP-SMX diet. The current findings supported the use of a BS-enriched diet as an eco-friendly approach for the control of V. cholerae in O. niloticus. [ABSTRACT FROM AUTHOR]

Nile tilapia (Oreochromis niloticus), native to Africa and the Levant, is an important species for both aquaculture and capture fisheries. Despite these attributes, Nile tilapia has been negatively impacted by anthropogenic activities ranging from overfishing and habitat destruction to translocations. These human‐mediated activities have threatened the genetic evolutionary integrity of native populations of Nile tilapia and congeneric species through admixture, demographic bottlenecks and introgressive hybridization. In this context, the genetic contrast between farmed/bred strains and wild Nile tilapia populations in the major lakes of Uganda remains understudied. Understanding the genetic structure of Nile tilapia populations in the major water bodies of Uganda (lakes Victoria, Kyoga, Edward, George, Albert and Nile River) is a key resource to guide selective breeding programmes, thus minimizing the effects of maladaptation under both aquaculture and natural stocks. Although the population genetics of Nile tilapia in Uganda's major lakes have been studied, this was based on limited sampling scope, especially in the wild, and the key information on the species could have been overlooked. We fill this knowledge gap by genotyping 756 Nile tilapia individuals from multiple populations for each major water body of Uganda using a panel of 34 microsatellite loci based on the microsatellite genotyping‐by‐sequencing (SSR‐GBS) technique. The results indicate two discrete gene pools/stocks: the Edward‐George system and the Albert‐Kyoga system‐Victoria. Evidence of loss of genetic diversity and admixture of some Nile tilapia stocks was found, most likely resulting from anthropogenic perturbations. This study contributes useful information key for understanding the potential Nile tilapia broodstock sources for selective breeding programmes, aimed at improving aquaculture production in Uganda. [ABSTRACT FROM AUTHOR]

Fish feed production is fraught with high costs due to the inclusion of expensive fishmeal and animal proteins that can be sourced from aquatic macrophytes. Limited attempts have been made on use of the latter for fish feed production. Further, the quality of feed given to fish is known to affect its growth and reproductive performance. Role of feeds containing duckweed (Lemna minor) at 0%‐control feed, 10%, 15%, 20% and 25% inclusion levels on growth and reproductive performance of Oreochromis niloticus of size 18 ± 1 g were evaluated for 12 weeks. The fish were fed twice daily at 10% body weight at 9.00 a.m. and 4.00 p.m. Length–weight measurements were done fortnightly using a measuring board and a weighing balance, respectively. Female mouth‐brooding fish were used to evaluate reproductive performance indicators, namely %: fertilization, hatchability and survivability. Data were subjected to one‐way analysis of variance followed by post hoc and polynomial orthogonal analysis to identify L. minor diets with significant differences (p < 0.05). Fish fed on a diet containing 10% L. minor inclusion showed significantly better growth performance and feed conversion ratio than those fed on the control diet. All L. minor diets gave good fish condition factors above 1.0. Fish fed on a diet containing 10% L. minor and those fed on the control gave reasonably high survival rates of 85.55% and 83.33%, respectively, whereas those fed on 20% L. minor produced the same growth performance as control. Orthogonal polynomial analysis for the final weights across the L. minor diets – 0%–25% – showed a cubic polynomial model (p = 0.000), whereas final lengths portrayed a linear inverse significant relationship (p < 0.05). Inclusion of L. minor in the diets resulted to slightly better fertilization, hatchability and survivability rates at 10%, 20% and 15%, respectively. In conclusion, inclusion of L. minor from 10% to 20% in fish feeds is recommended for enhancing growth and reproductive performance of O. niloticus. [ABSTRACT FROM AUTHOR]

This study investigated the effect of natural compounds from Nile tilapia (Oreochromis niloticus) skin on wound healing in IL-10 knockout mice. The healing fraction, Fraction T19, was obtained through hydrolysis with trypsin. In vitro, T19 was not cytotoxic to RAW 264.7 macrophage cells, promoting increased cell proliferation and migration. In vivo, mice (n = 30) were divided into three groups with 12 mm wounds in the dorsal region: control (distilled water), T1 (T19 at 125 μg/mL), and T2 (T19 at 250 μg/mL). Daily applications were performed, with tissue removal after nine days. The results showed that T19 increased the production of nitric oxide (NO) and hydrogen peroxide (H2O2), preventing wound contamination. There was an increase in pro-inflammatory (IL-2 and IFNγ) and anti-inflammatory (IL-4) cytokines, as well as cell proliferation markers (PCNA and KI67). Antibodies CD31, CD163, and COX-2 indicated an increase in the formation of new vessels and a reduction in inflammation. Both groups treated with T19 showed better healing results, with better effects observed at higher doses. It was concluded that T19 can effectively modulate the skin repair process and represent an alternative therapeutic for improving the quality of wound skin, especially in the clinical context. Formulations using tilapia skin are safe and effective for accelerating wound healing. [ABSTRACT FROM AUTHOR]

Classical assessments of new fish feeds are anthropocentric, focusing mainly on growth. Although this methodology is accurate, it does not consider the fish' perspective. This study aimed to investigate the behavioural responses and feed preferences of Nile tilapia (Oreochromis niloticus) and gilthead seabream (Sparus aurata) through a self-selection trial using self-feeders. Both species were offered three feeds: a control (PD) commercial-like feed and two diets (ORG1 and ORG2) formulated with different inclusions of alternative ingredients to address some of the current environmental concerns and/or ethical issues often associated with commercial formulations. Three groups of tilapia with an average weight of 163.0 g ± 4.3 g (mean ± SD) and four groups of seabreams with 174.7 g ± 27.0 g were tested. Tilapia exhibited a preference for ORG2 (46.5%), influenced by the sensory properties of the feed and post-ingestion signals. Seabream did not show a preference for any feed. These findings highlight the effectiveness of self-selection experiments in allowing fish to express their feeding behaviour and preferences. Therefore, this approach should be considered in the initial screening and design of new aquaculture feeds and ingredients. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems, especially lakes, constitute vital reservoirs of potable water, irrigation resources, and aquaculture habitats. However, there is a lack of comprehensive data regarding the prevalence of microplastics (MPs) in freshwater lakes of densely populated metropolitan regions in the Indian Subcontinent. In this study, we have investigated the qualitative and quantitative attributes of MPs in the surface waters of four important lakes in Pune, India: (i) Kasarsai, (ii) Pashan, (iii) Manas, and (iv) Mastani. Our analyses revealed prevalent contamination across all four lakes, with Kasarsai lake exhibiting the highest mean MPs abundance of 14.03 ± 5.41 particles/L. Primary morphotype of MPs detected in the water samples were fibres and the dominant size was between 100 µm to 1000 µm. Additionally, in terms of colour, transparent microplastics were prominent. Fourier Transform Infrared Spectroscopy (FTIR) revealed that polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) were the main types of MPs present in water samples. Furthermore, we assessed the abundance of MPs ingested by commercially available edible fish Tilapia, Oreochromis niloticus, collected from these lakes. We observed maximum ingestion of MPs in the fish from Kasarsai lake, which was 2.8 ± 2.9 particles per individual fish. To evaluate the possible health risks on humans, Estimated Daily intake (EDI) and Microplastics Cancer Risk (MPCR) index were determined for adults and children. EDI of PP was highest for Kasarsai and Manas lake, while, EDI of PE was predominant for Pashan and Mastani lake. For all four lakes, the MPCR index of PE was highest in both adults and children, with the maximum reaching to 0.52 for children consuming water from Pashan lake. Our findings raise concerns about the potential negative effects of MPs on freshwater ecosystem and the health of humans consuming the water and fish from such lakes. An ambitious strategy involving the collective efforts of the general public is required to address this hazard. [ABSTRACT FROM AUTHOR]

Among 79 Bacillus spp. isolated from Miang, a fermented tea in north Thailand, 17 Bacillus strains were selected with probiotic potential in Nile tilapia culture based on the capabilities of bacteriocin production and associated antimicrobial activities against fish pathogens, Aeromonas hydrophila and Streptococcus agalactiae. However, only six isolates were selected for further extensive studies based on the strength of their antimicrobial activities and their tolerance against simulated gastrointestinal conditions. The molecular identification by 16S rRNA gene sequence analysis revealed that five isolates, K2.1, K6.1, K7.1, K15.4, and K22.6, were Bacillus tequilensis, and the isolate K29.2 was Bacillus siamensis. B. siamensis K29.2 showed complete susceptibility to antibiotics tested in this study, while B. tequilensis K 15.4 showed moderate resistance to some antibiotics; therefore, both strains were selected as potential probiotic bacteria. B. tequilensis K15.4 and B. siamensis K29.2 were capable of the production and secretion of extracellular protease and polysaccharide degrading enzymes, including cellulase, xylanase, and β-mannanase. The tannin tolerant test also demonstrated their ability to grow on selective agar plates and secrete cellulase and β-mannanase in the presence of hydrolyzable tannin. In addition, in vitro digestion of commercial fish substrate revealed that the extracellular enzymes produced by both strains efficiently reacted with feed protein and polysaccharides. Based on the results from this study, B. siamensis K29.2 was deemed to have the highest potential multifunctional probiotic qualities for application in Nile tilapia culture, while the antibiotic-resistant gene in B. tequilensis K15.4 must be clarified before field application. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of postmortem chilling times (4 °C: 0, 2, 8, and 12 h) and subsequent frozen storage durations (-20 °C: 0, 1, 2, and 3 months) on the microstructure and protein properties of tilapia fillets. Tilapia fillets with 8 h of chilling (P8) resulted in highest overall acceptability, hardness, chewiness, and shear force. The thawing losses of tilapia fillets with different postmortem chilling times for the same frozen storage duration were ranked as follows: P12 > P0/P2 > P8. With the prolongation of postmortem chilling times and frozen storage periods, the muscle tissue structure was gradually damaged, with the most severe disruption after 12 h of postmortem chilling time. Tilapia fillets pre-chilled for 8 h showed a 17.63% decrease in Ca2+-ATPase activity at 3 months of frozen duration, which was the smallest decrease compared with the other groups. Furthermore, the endogenous fluorescence intensity of P0, P2, P8 and P12 samples decreased by 34.53%, 14.29%, 13.95% and 26.98%, respectively, at the end of frozen storage. Overall, frozen storage durations had a greater effect on the quality of tilapia fillets than postmortem chilling times. In summary, the maximum postmortem chilling time for frozen tilapia fillets is recommended to be 8 h, with significant quality differences when frozen for more than 2 months. [ABSTRACT FROM AUTHOR]

Vaccination is an approved novel approach for controlling aeromonads disease caused by Aeromonas hydrophila. This study aimed to optimize the A. hydrophila vaccine candidate with a protective efficacy of 71.4% through immersion. A total of 600 tilapia fingerlings weighing 10–15 g were collected and distributed in tanks at Magadu farm. The fingerlings acclimatized for 2 weeks. Vaccination was done by immersion at a dose of 1.6 × 108 cfu/mL mixed as 1 part of a vaccine in 20 parts of tank water. A total of 150 fingerlings were exposed to a vaccine for 30 min and distributed in three replica tanks, each having 50 fingerlings. The same procedure was applied to fingerlings exposed to the vaccine at 45 and 75 min, while the remaining 150 fingerlings served as control. Fish were bled at day 0 and days 7, 14, 21, and 28 postvaccinations for immunogenicity studies. A challenge trial with a virulent A. hydrophila followed. Observation for mortalities and clinical signs was made for 28 days postchallenge. No clinical signs and death were observed during the entire period of 28 days postvaccination. The serology findings showed higher antibody titer of 45 min vaccination time of exposure (GMT log 2 = 5.0 at day 28). The findings revealed that the protective efficacy had increased to 90% relative percent of survival at 45 min duration of vaccine exposure. The vaccine demonstrated acceptable safety and protection levels on the field. [ABSTRACT FROM AUTHOR]

Tilapia is one of the most important farmed fish in the world and the most cultivated in Brazil. The increase of this farming favors the appearance of diseases, including bacterial diseases. Therefore, the aim of this study was to evaluate the bactericidal activity of copaiba oil, Copaifera duckei, against Streptococcus agalactiae and Flavobacterium columnare and the dietary effect of copaiba oil on zootechnical performance, hematological, biochemical, immunological, and histological analysis before and after an intraperitoneal infection (body cavity) with S. agalactiae in Nile tilapia. For this, fish were randomly distributed into 15 fiber tanks in five treatments (0, 0.25, 0.50, 0.75, and 1.0%) and fed with a commercial diet supplemented with copaiba oil for 30 days. After this period, the fish were randomly redistributed for the experimental challenge with S. agalactiae into six treatments (T0, T1, T2, T3, T4, and T5), the fish were anesthetized, and blood samples were collected to assess hematological, biochemical, immunological, and histological parameters. Copaiba oil showed bactericidal activity against Streptococcus spp. and Flavobacterium spp. in vitro. In addition, concentrations of 0.75 and 1.0% of copaiba oil have an anti-inflammatory effect and improve hematological and immunological parameters, increasing leukocyte numbers, albumin, and serum lytic activity. Furthermore, there is an increase in the intestinal villus length and tissue damage in groups at concentrations of 0.75 and 1.0% of copaiba oil. In conclusion, copaiba oil presented bactericidal activity against Streptococcus spp. and Flavobacterium spp. in vitro, and oral supplementation at concentrations of 0.75 and 1.0% compared to the control group enhanced non-specific immune parameters and digestibility in Nile Tilapia. [ABSTRACT FROM AUTHOR]

The liver is essential for nutritional balance in fish, and liver damage in farmed fish often arises from factors like overfeeding, causing various health issues. Clinical observations indicate that liver diseases frequently involve spleen dysfunction, and there is evidence to suggest that the spleen has a significant impact on liver function. However, there has been no discussion on the role of the spleen in maintaining liver health in fish. To understand the role of fish spleen in liver metabolism, this study selected Nile tilapia (Oreochromis niloticus) as the experimental material and first established a tilapia splenectomy model. Various biochemical parameters of the liver and serum were measured, and the liver metabolism characteristics of the splenectomy group (SP group) and the sham operation group (SO group) were analyzed using metabolomics. After splenectomy, biochemical parameters of the liver and serum showed abnormalities, including significant increases in total cholesterol (T-CHO) and serum total bile acid (TBA) levels, alongside a significant decrease in liver TBA levels, suggesting impaired metabolic function and cholesterol deposition in the liver. Metabolomics analysis showed that metabolites such as lipids, lipid-like molecules, and organic acids and derivatives were differentially regulated between the SO and SP group. KEGG analysis showed that differential metabolites were enriched in lipid metabolism and amino acid metabolism. The metabolic pathway analysis of differential metabolites showed that after splenectomy, the low-activity urea cycle in the liver may accelerate lipid synthesis, while low concentrations of aromatic amino acids and taurine may inhibit lipid catabolism. These results indicate that after splenectomy, the liver metabolic capacity is impaired, which causes abnormal lipid metabolism by interfering with amino acid metabolism, making splenectomy tilapia liver at risk of liver disease, including cholesterol deposition, hepatic steatosis and nonalcoholic fatty liver disease (NAFLD). Our results show that the spleen is involved in regulating liver lipid and amino acid metabolism, and the spleen may interfere with lipid metabolism by regulating liver amino acid metabolism. Our data can provide support for further research on liver and spleen functions and the immune-nutrient metabolism mechanisms in fish, as well as new ideas for healthy fish farming. [ABSTRACT FROM AUTHOR]

Background: Gills monogenean infestation causes significant mortalities in cultured fishes as a result of respiratory manifestation. Medicinal plants are currently being heavily emphasized in aquaculture due to their great nutritional, therapeutic, antimicrobial activities, and financial value. Methods: The current study is designed to assess the effect of garlic (Allium sativum) and onion (Allium cepa) extracts as a water treatment on the hematological profile, innate immunity, and immune cytokines expression besides histopathological features of gills of Nile tilapia (Oreochromis niloticus L.) infected with gills monogenetic trematodes (Dactylogyrus sp.). Firstly, the 96-hour lethal concentration 50 (96 h-LC50) of garlic extract (GE) and onion extract (OE) were estimated to be 0.4 g/ L and 3.54 g/ L for GE and OE, respectively. Moreover, the in-vitro anti-parasitic potential for (GE) was found between 0.02 and 0.18 mg/mL and 0.4 to 1.8 mg/mL for OE. For the therapeutic trial, fish (n = 120; body weight: 40–60 g) were randomly distributed into four groups in triplicates (30 fish/group, 10 fish/replicate) for 3 days. Group1 (G1) was not infected or treated and served as control. G2 was infected with Dactylogyrus spp. and not exposed to any treatment. G3, G4 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of OE, respectively. G5, G6 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of GE, respectively. Results: No apparent signs or behaviors were noted in the control group. Dactylogyrus spp. infected group suffered from clinical signs as Pale color and damaged tissue. Dactylogyrus spp. infection induced lowering of the hematological (HB, MCH, MCHC and WBCs), and immunological variables (lysozyme, nitric oxide, serum Anti- protease activities, and complement 3). the expression of cytokine genes IL-ß and TNF-α were modulated and improved by treatment with A. sativum and A. cepa extracts. The obtained histopathological alterations of the gills of fish infected with (Dactylogyrus spp.) were hyperplasia leading to fusion of the gill filament, lifting of epithelial tissue, aneurism and edema. The results indecated that G4 and G5 is more regenarated epithelium in compare with the control group. Conclusion: A. sativum and A. cepa extracts enhance the blood profile and nonspecific immune parameters, and down-regulated the expression level of (IL-1β and TNF-α). [ABSTRACT FROM AUTHOR]

The present study evaluated the capacity of three Bacillus species to improve health status and growth performance of Nile Tilapia fed with high levels of soybean meal and challenged with Aeromonas hydrophila. In vitro experiments showed that b-hemolysin and metalloprotease enzymes were produced by A. hydrophila throughout the exponential growth phase. In vivo experiments showed that 107 colony-forming units (CFUs)/ml of this pathogen killed 50% of control group fishes in 13 days. To evaluate the influence of Bacillus strains on health status and growth performance in Nile Tilapia, 180 fishes (33.44 + 0.05 g) were distributed in 12 tanks of 200 L each, and animals were fed twice per day until satiety. 1) Control group without Bacillus, 2) Bacillus sp1, 3) Bacillus sp2, and 4) Bacillus sp3 groups were formulated containing 106 CFU/g. After 40 days of feeding, the fishes were intraperitoneally injected with 1 ml of A. hydrophila at 2 × 107 CFU/ml, and mortality was recorded. The results showed that cumulative mortality rate was significantly (p< 0.05) lower in the Bacillus sp1 (25%), sp2 (5%), and sp3 (15%) groups, than the control group (50%). Weight gain was also significantly better (p< 0.05) in the Bacillus sp1 (36%), sp2 (67%), and sp3 (55%) groups with respect to the control group (30%). In conclusion, functional diet formulated with high levels of soybean meal and supplemented with Bacillus sp2 could be an alternative to protect Nile tilapia cultures from A. hydrophila infections and improve fish growth performance. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have recently been detected as emergent pollutants in the Ethiopian rift valley lakes located close to rapidly expanding towns. We provide the first study of MPs ingestion of commercial fish species from Lake Hawassa, Ethiopia: Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus). A total of 60 individual fish species was collected from three sampling sites of lake Hawassa in October 2020. Across all sampling sites, there was a significant difference in ingested MPs between benthic omnivore catfish and pelagic phytoplanktivorous Tilapia (χ2 = 15.864, p < 0.001). The most common size of ingested MPs (84.6%) was 0.5–1 mm, with fragments (59.5%) dominating, followed by fibers (25.4%). On average, 4.03 ± 1.33 MPs with sizes ranging between 60 μm and 10.53 mm were detected per individual. White and yellow MPs were particularly numerous, accounting for 36.8% and 26.4% of the total, respectively. Because Lake Hawassa's fishery is so significant, the potential impact of MP pollution on the lake biota in general, and economically valuable fish species in particular, deserves attention, additional research, and, if possible, early mitigation. [ABSTRACT FROM AUTHOR]

Latin America (LATAM) plays an important role in the world's production of aquatic animals and is the second most productive region in the world. Chile, Ecuador, Brazil, Mexico, Colombia, and Perú contribute 87% of LATAM aquaculture production. The fish welfare in aquaculture is of increasing public concern globally, and LATAM is no exception, growing in importance for fish farmers, authorities, and scientists. Although the topic is somewhat controversial, the welfare status of farmed fish has direct implications for their production and the sustainability of the industry. Therefore, this study analyses scientific papers on animal welfare in farmed fish, from the six countries in LATAM with the highest aquaculture production. The main objectives were to quantify the number of papers published between 2000 and 2023 on fish welfare by using scientific databases. A total of 285 papers were found for the period analysed. The country with the largest number of publications was Brazil (75.79%), followed by Chile (13.33%), Mexico (7.02%), Peru (1.75%), Ecuador, and Colombia (1.05%). Nile tilapia was the most studied species, appearing in 30.18% of the publications, with most of the studies mainly dealing with nutrition (32.28%). The growth of aquaculture is leading to joint efforts to generate knowledge on welfare issues, especially in poorly studied species with high production, to create policies that help minimize welfare risks. Given this, the insights generated by this review could be a useful addition to approaches investigating the trends and concepts of fish welfare in LATAM. [ABSTRACT FROM AUTHOR]

Introduction: The circular bioeconomy concept revolves around biological production cycles that reintroduce products or waste from one production system to another, aiming to maximize resource utilization while minimising environmental impact. The purpose of this study was to evaluate and compare the element flow when integrating black soldier fly larvae (BSF) production with Nile tilapia production using varying experimental fish feed. Methods: Tilapia (42.5 ± 11.2 g) were reared in recirculating aquaculture systems (RAS) at 25.5°C for 10 weeks and fed equal daily rations of four experimental diets containing fishmeal (FM), poultry blood meal (PBM), black soldier fly meal (BSF) and poultry by-product meal (PM) as the single main protein source, respectively. Faeces was collected daily from settling columns installed in the RAS and subsequently fed to BSF larvae. Results and discussion: The fish exhibited the highest biomass gain when fed with FM (1,001 g) or PM (901 g). The growth was lowest for those fed with PBM (406 g). The fish fed with PBM also produced the highest amount of faeces (234 g). When the fish faeces were utilized as a substrate for rearing black soldier fly (BSF) larvae and although the biomass gain did not differ significantly, the feed conversion ratio (FCR) varied among larvae fed with different fish faeces, ranging from 8.36 to 25.04. Furthermore, the concentration of analysed elements (Al, B, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, and Zn) varied based on the type of fish faeces provided. Results illustrate that a modulation of BSFL elemental composition is possible through manipulating the feed provided to the fish and emphasize the importance of fish feed composition for fish performance as well as the compositional quality of the larvae reared on the resulting fish faeces. Hence, if BSF larvae production is to be harnessed for the recycling of aquaculture sludge, ingredient choice and subsequent elemental composition of fish feeds are pivotal to larvae composition. [ABSTRACT FROM AUTHOR]

Various types of professional immune cells first emerge in fish and likely represent the primordial form and functions. Recent advancements revealed the direct connection between the central nervous system and the immune system in the mammalian brain. However, the specifics of brain-immune networks in the fish and the underlying mechanisms of teleost's brain against pathogen infection have not been fully elucidated. In this study, we investigated the distribution of markers representing cerebral cells associated with protection and professional lymphocytes in the seven major components of the Nile tilapia brain through RNA-Seq assay and observed the most dominant abundance in the medulla oblongata. The subsequent challenge test revealed the non-specific cytotoxic cells (NCCs) exhibited the strongest response against streptococcal infection of the brain. The presence of NCCs in the brain was then confirmed using immunofluorescence and the cytotoxic effects usually induced by NCCs under infection were determined as well. Collectively, these findings contribute significantly to comprehending themechanismof fish neuroimmune interaction and enhancing our understanding of its evolutionary development. [ABSTRACT FROM AUTHOR]

Haemoglobin concentration ([Hb]) assessment in fish blood has become a routine parameter to measure the health and welfare status of the animals. The original method (haemoglobincyanide method, best known as the Drabkin method) for measuring Hb in human and animals is not well suited for work outside of a laboratory setting. It is relatively time consuming, contains hazardous cyanide elements, and requires specific laboratory material. As an alternative to the Drabkin method, portable analysers have been developed for human blood, but they need to be first validated for fish blood before being used in experiments. In this study, the performance of the new HemoCue Hb 801 portable haemoglobin analyser was compared to the validated Drabkin method to determine [Hb] in three fish species. Hb readings between the two methods were not different for any of the species tested (rainbow trout, Onchorynchus mykiss, Atlantic wolffish, Anarhichas lupus, and Nile tilapia, Oreochromis niloticus). Therefore, this new portable device can be readily used to measure Hb in fish blood. Unlike the previous model from HemoCue, the Hb 201+, this device does not need an incubation time or a correction factor, representing a major gain of time and precision. [ABSTRACT FROM AUTHOR]