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Recent research has looked at various macroalgae species as dietary components or feed additives for a variety of fish species due to their nutritional value. The objective of this study was to examine the impact of Najas indica, a macroalgae extract, on the growth performance, proximate composition, and metabolic activities of monosex tilapia (Oreochromis niloticus), while also isolating the compounds present. Three distinct solvents (n‐hexane, ethyl acetate, and ethanol) were used to extract bioactive compounds from a coarse powder of macroalgae after drying and grinding, and gas chromatography–mass spectrometry (GC–MS) analysis was used to detect bioactive compounds. The extracts were combined with commercial feed (0.4%) and applied to the treatment with three replications and a control containing 50 fingerlings per tank for 5 weeks. The findings indicated a significant increase in the final weight, weight gain, specific growth rate (SGR), and survival rate among the treated fish, whereas the feed conversion ratio (FCR) was observed to decrease in comparison to the control group. Significantly higher levels of protein and lipids were found in treated fish, whereas moisture and ash levels were significantly lower compared to control fish. In treated fish, the digestive enzyme amylase was significantly higher, but the protease enzyme reduced significantly. The antioxidant enzyme superoxide dismutase activity (SOD) was significantly higher in the treatment group, whereas the catalase (CAT) enzyme did not differ significantly. A total of 47 bioactive compounds were identified in N. indica, among which the prominent compounds included n‐hexadecanoic acid, neophytadiene, phytyl palmitate, d‐mannitol, and heptanoic acid. The results obtained from this study indicate that the utilization of N. indica macroalgae extract has the potential to serve as an additional dietary component, therefore, enhancing the growth performance and metabolic functions of fish. [ABSTRACT FROM AUTHOR]

Cichlidogyrus spp. are dactylogyridean ectoparasites of wild cichlids and cultured Nile tilapia that occur in several regions worldwide. They can be abundant in intensive Nile tilapia culture and cause mild to severe gill pathogenic effects that frequently are overlooked. From January to June 2018, a follow-up study was conducted on an intensive farm where 360 Nile tilapia were sampled and analyzed throughout a six-month culture cycle. During the survey, a population of monogeneans was observed to increase steadily over the course of the production cycle. To corroborate the status of these parasites, 13 additional farms were visited from January to April 2020, where a total of 130 Nile tilapia were examined. This secondary sampling aimed to identify and corroborate the dominant monogenean species and the infection dynamics, including the associated histopathological damages. Nine species of the genus Cichlidogyrus (Cichlidogyrus sp. C. bifurcatus, C. dossoui, C. halli, C. haplochromii, C. longicornis, C. sclerosus, C. thurstonae and C. tilapiae) were recovered from the gills and identified. Overall, Cichlidogyrus sclerosus was the most prevalent and abundant parasite. Also, significant differences were found in the monthly prevalence and intensity of C. sclerosus, especially in the fourth month of culture when the population peaked (Chi-square, p < .001; p < .001, respectively). Correlations were observed between temperature, nitrite, and C. sclerosus intensity. Four left gill arches of 130 Nile tilapia collected in the farms were removed and fixed at 10% formalin for histopathological examination. Histological alterations in gills tissues were graded by severity scores. Gills, at the site of monogenean attachments, showed mucus secretion, hyperplasia, hypertrophy, and lamellar fusion involving mucous cells, depending on the intensity of the damage. [ABSTRACT FROM AUTHOR]

Aquafeed additive quality and quantity remain pivotal factors that constrain the sustainability and progress of aquaculture feed development. This study investigates the impact of incorporating the benthic diatom Amphora coffeaeformis into the diet of Nile tilapia (Oreochromis niloticus) broodstock, on the blood biochemistry, steroid hormone (SH) levels and seed production efficiency. Broodstock females displaying mature ovary indications were initially combined with males at a ratio of three females to one male. A total of 384 adult Nile tilapia (288 females and 96 males) were used, with 32 fish (24 females and eight males) assigned to each of 12 concrete tanks (8 m³; 2 m × 4 m × 1 m), with three replicate tanks for each dietary treatment, throughout a 14‐day spawning cycle until egg harvest. Fish were fed one of four different dietary treatments: AM0% (control diet), and AM2%, AM4% and AM6% enriched with the diatom A. coffeaeformis at levels of 20, 40 and 60 g/kg of diet respectively. At the trial's conclusion, total protein, albumin, triglyceride and creatinine), SHs (follicle‐stimulating hormone, luteinizing hormone, free testosterone, total testosterone, progesterone and prolactin) and seeds production efficiency of Nile tilapia improved significantly (p < 0.05) in alignment with the increment of A. coffeaeformis supplementation. The findings propose that including A. coffeaeformis at levels ranging from 4% to 6% could be effectively employed as a feed additive during the Nile tilapia broodstock's spawning season. [ABSTRACT FROM AUTHOR]

This study aimed to perform in vitro antiparasitic and antimicrobial tests with the essential oil (EO) of Schinus terebinthifolius against of fish and shrimp. The chemical composition of the EO of S. terebinthifolius was determined by gas chromatography. For the antiparasitic test, the protozoan Epistylis sp. obtained from parasitized Oreochromis niloticus was used, and exposed to different concentrations of EO (2%, 1%, 0.5%, 0.25%), and control with 1% grain alcohol. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) test with EO of S. terebinthifolius evaluated the antimicrobial potential, with serial dilutions starting at 2% and control with 1% grain alcohol, using the strains of Aeromonas hydrophila (2.2 × 108 CFU mL−1), Edwardsiella tarda, Vibrio parahaemolyticus, V. harveyi, and V. alginolyticus (2.0 × 108 CFU mL−1). Chemical analysis revealed that the major EO compounds of S. terebinthifolius were δ‐3‐Carene (56.00%) and α‐Pinene (16.89%). In the antiparasitic test, the concentration of 2% EO showed 100% efficacy against Epistylis sp. within 5 min. In the antimicrobial tests, the concentration of 2% EO was effective against all bacteria tested. The EO of S. terebinthifolius demonstrated antiparasitic and antimicrobial activity at a concentration of 2%, standing out as an alternative to conventional antibiotics. [ABSTRACT FROM AUTHOR]

Channel catfish (Ictalurus punctatus) and Nile tilapia (Oreochromis niloticus) are two aquaculture species of great importance. Intensive production is often hindered by poor growth performance and disease mortality. The aim of this study was to evaluate the potential of a commercial fermented yeast product, DVAQUA, on channel catfish and Nile tilapia growth performance metrics and disease resistance. Channel catfish and Nile tilapia were fed practical diets supplemented with 0%, 0.1% or 0.4% of DVAQUA over approximately 2‐month feeding periods in recirculation aquaculture systems. To assess the potential of the postbiotic against common aquaculture pathogens, juvenile catfish were subsequently challenged by immersion with Edwardsiella ictaluri S97‐773 or virulent Aeromonas hydrophila ML09‐119. Nile tilapia juveniles were challenged by injection with Streptococcus iniae ARS‐98‐60. Serum lysozyme activity, blood chemistry and growth metrics were measured at the end of the feeding period, but no differences were observed across the different metrics, except for survival. For the pathogen challenges, there were no differences in endpoint mortality for channel catfish with either pathogen (p >.05). In contrast, Nile tilapia survivability to S. iniae infection increased proportionally to the inclusion of DVAQUA (p =.005). Changes to sera lysozyme activity were also noted in the tilapia trial, with a reduction of activity in the fish fed the 0.4% DVAQUA diet compared to the control diet (p =.031). Expression profiles of proinflammatory genes and antibodies were also found to be modulated in channel catfish fed the postbiotic, indicating some degree of protective response. These results suggest that this postbiotic may be beneficial in protecting Nile tilapia against S. iniae infection by influencing immune parameters and additional research is needed to evaluate the potential of this DVAQUA for improving catfish health and disease control. [ABSTRACT FROM AUTHOR]

Globally, streptococcal disease caused by Streptococcus agalactiae is known for its high mortality rate, which severely limits the development of the tilapia breeding industry. As a third‐generation vaccine, DNA vaccines have shown great application prospects in the prevention and control of aquatic diseases, but their low immunogenicity limits their development. The combination of DNA vaccines and molecular adjuvants proved to be an effective method for inducing protective immunity. This study constructed recombinant plasmids encoding tilapia HSP70 and IL‐1β genes (pcHSP70 and pcIL‐1β) to verify their effectiveness as molecular adjuvants for S. agalactiae DNA vaccine (pcSIP) in the immunized tilapia model. The results revealed that serum‐specific IgM production, enzyme activities, and immune‐related gene expression in tilapia immunized with pcSIP plus pcHSP70 or pcIL‐1β were significantly higher than those in tilapia immunized with pcSIP alone. It is worth noting that combination with molecular adjuvants improved the immune protection of DNA vaccines, with a relative percentage survival (RPS) of 51.72% (pcSIP plus pcHSP70) and 44.83% (pcSIP plus pcIL‐1β), respectively, compared with that of pcSIP alone (24.14%). Thus, our study indicated that HSP70 and IL‐1β in tilapia are promising molecular adjuvants of the DNA vaccine in controlling S. agalactiae infection. [ABSTRACT FROM AUTHOR]

Aim: Many fish species can harbour a wide range of pathogenic agents in their tissues. Of many pathogens, the parasitic nematode of genus Contracaecum, which resides in the tissues of fish species, can results in fish‐borne infections in humans. This study was planned to assess consumers' awareness of fish‐borne zoonoses in the fishing sites of Lake Chamo, Arba Minch, Ethiopia. The study was also aimed at demonstrating the zoonotic nematode, Contracaecum parasites in the Oreochromis niloticus and Lates niloticus fishes collected from Lake Chamo, Arba Minch, Ethiopia. Methods and Results: Assessment of awareness about fish‐borne zoonoses was conducted in randomly selected participants (n = 162) using face‐to‐face interviews via a structured and semi‐structured questionnaire. Besides, 70 fishes (O. niloticus = 35 and L. niloticus = 35) were examined for the presence of larva of Contracaecum and other anisakid genera through standard dissection, pepsin‐hydrochloric acid digestion and microscopic observation. Consumers have inadequate awareness about fish‐borne zoonoses based on the answers they provided to the questions. The majority of respondents (82%) consume raw fish in the area. Of these, a significantly higher proportion were male (p < 0.001), completed their elementary or high school (p = 0.004), Orthodox Christian (p = 0.044), fishermen (p < 0.001) and participants without previous information about fish‐borne zoonoses (p < 0.001). Overall, of examined fishes (n = 70), n = 15 (21.4%, 95% CI, 12.8–33.2) were infected with Contracaecum larva. A significant (p = 0.028) higher infection prevalence was noted in L. niloticus (34.3%, 95% CI, 19.7–52.3) compared to O. niloticus (8.6%, 95% CI, 2.2–24.2). A unit gram addition in the total weight of fish would significantly raise the risk of Contracaecum infection by 1% (p < 0.001). Conclusions: The presence of Contracaecum, a zoonotic nematode in the fishes, which are often preferred by consumers for raw dishes, designates a high risk of possible fish‐borne infections in the area. Thus, providing education and training for fishermen, visitors of the area, and local people who visit the area for fish consumption, it is inevitably important to minimize the risk. Furthermore, health workers should suspect fish‐borne infections, such as anisakidosis in patients who have a history of raw fish consumption in Arba Minch, Ethiopia. [ABSTRACT FROM AUTHOR]

Tilapia aquaculture is rapidly expanding worldwide, particularly in Bangladesh. However, metal pollution in aquaculture presents significant environmental and human health risks. This study aimed to evaluate the concentrations of 13 potentially toxic metals (As, Be, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Mn, Se, and Zn) in Nile tilapia (Oreochromis niloticus), surface water, and sediment from freshwater and brackish water aquaculture ponds. The study also assessed the associated environmental and human health risks. Samples of tilapia, water, and sediment were collected between October and November 2021 and analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The estimated daily intake (EDI) of As, Cr, Pb, Se, and Zn in tilapia muscle of both freshwater and brackish water, as well as Cd and Ni in brackish water, exceeded recommended EDI values. The Target Hazard Quotient (THQ) was less than 1 for most metals, except for As in brackish water tilapia and Cr in both freshwater and brackish water tilapia, indicating potential health risks. The Target Cancer Risk (TR) values for As in both freshwater and brackish water tilapia, and for Cr and Ni in freshwater tilapia, exceeded acceptable ranges. While the concentrations of metals in surface water of both freshwater and brackish water tilapia farms varied, all mean concentrations were below WHO recommended limits. The contamination factor (Cf) values were less than 1 for all metals in both types of aquaculture ponds, except for Zn in freshwater sediment and Se in brackish water sediment. Additionally, the calculated risk indices including the Pollution Load Index (PLI), Geoaccumulation Index (Igeo), Ecological Risk Factor (Er), and Potential Ecological Risk Factor (PER) for sediment were below the risk thresholds values (PLI < 1, Igeo < 0, Er < 40, and PER < 150). The significant positive correlations were found between tilapia muscle and the sediment of the respective ponds for arsenic (As) (ρ= 0.8, p<0.002) and Cr (ρ= 0.7, p<0.02). Although the levels of studied metals in water and sediment from freshwater and brackish water aquaculture ponds were generally within recommended guidelines, this study underscores the need for continuous monitoring and preventative measures, particularly to address elevated levels of As and Cr in tilapia muscle, which may pose potential risks to human health. [ABSTRACT FROM AUTHOR]

The present study was carried out to evaluate the impact of fish silage (FS) on the growth performances, protease enzyme activity and muscle compositions of Nile tilapia. In this regard, FS was produced from the waste parts of carp, pangus and tilapia and five iso-nitrogenous (containing 35% crude protein) diets were formulated in which fishmeal (FM) was used as the primary protein source in the control diet (0% FS, T1). The remaining four diets were formulated by replacing 25% (T2), 50% (T3), 75% (T4), and 100% (T5) FM protein with the FS. These diets were fed to tilapia at 8-6% of their body weight rearing them in glass tanks at the density of 15 fish/tank in triplicates. After fifty-days feeding trial, survival (%) of fish remained unaffected among the dietary treatments. Tilapia fed with 75% FS based diet showed improved growth and lower FCR, whereas those fed a diet with 100% FS exhibited lower growth rates. Notably, protease enzyme activity (mg/ml/min) increased with higher levels of FS inclusion. Increased crude protein content was observed in the fish fed the 75% FS diet. These findings underscore the potential of including FS up to 75% to enhance the growth performance of Nile tilapia. [ABSTRACT FROM AUTHOR]

Aquatic meals participate in food security and nutrition. The economic dimension greatly influences the sustainability of the aquaculture industry. This study aimed to assess the effects of partial substitution of soybean meal (SBM) with cottonseed meal (CSM) supplemented with ferrous sulfate (FS) on the growth performance and health status of Nile tilapia. One hundred and fifty Nile tilapia (Oreochromis niloticus) were split equally into five group (triplicated). Each group was fed one of the following isonitrogenous isolipid diet; diet1 (0% CSM), diet2 (20% CSM), Diets3 (20% CSM with 580 mg/kg (FS), diet4 (50% CSM), and diet5 (50% CSM with 580 mg/kg FS) of total protein for two months. In comparison to the control group, Statistically significant (p<0.05) improvements in growth performance, hemogram, and leukogram, as well as, the levels of ALT, AST, urea, creatinine, total protein, MDA, and GSH-px were observed in the third treatment. Histopathologically, it showed the highest values of villus height, width, and absorption surface area (ASA) with normal architecture and cellular details. On the other hand, fish fed diet4 had the lowest growth rat with microcytic normochromic anemia and decreased villus height, width and ASA. The groups that fed CSM showed lower cholesterol levels. In conclusion, CSM inclusion with FS supplementation enhanced growth and health parameters. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) and glyphosate‐based herbicides (GBH) are among the most common contaminants in aquatic environments. In Brazilian rivers, both contaminants were found in elevated levels, leading to a high probability of their association, which can alter their individual effects and potentially intensify their toxicity. This study evaluated the isolated and combined effects of polyethylene microplastics (PE‐MPs) and GBH on Oreochromis niloticus using multi‐biomarkers of toxicity. The fish were subjected to a 96‐h exposure period, with concentrations set based either isolated, PE‐MPs group (5 mg L−1), GBH group (5 mg L−1), or in a group of associated contaminants (GAC), PE‐MP + GBH (5 mg L−1 + 5 mg L−1). Toxicity effects were evaluated using biochemical, cytogenetic, hematological, and histopathological biomarkers. We observed change in erythrocyte parameters leading to macrocytic normochromic anemia in GAC. Leukocyte parameters indicate a nonspecific immunosuppression caused by the exposure of associated contaminants, besides the attempts to repair damage caused by PE‐MPs. Histopathological markers indicate damage to tissues exposed to contaminants. Besides, there were morphophysiological adjustments on gills, with proliferation and hypertrophy of mitochondria‐rich cells on GBH and GAC, besides epithelium ruptures, which were mostly present in the exposed groups. Therefore, this study indicates that PE‐MPs and GBHs present toxic effects in O. niloticus with the used concentrations, intensified by the association of contaminants. Thus, multi‐biomarkers were useful key to verify toxicity, providing data to the investigation of high levels of contaminant's mixture toxicity present in aquatic environments. [ABSTRACT FROM AUTHOR]

Fish-borne zoonotic trematodes (FBZTs) pose significant health risks and economic challenges worldwide. This study investigated the prevalence of encysted metacercariae (EMCs) in Nile tilapia (Oreochromis niloticus) from two Egyptian governorates and evaluated the antiparasitic efficacy of chitosan, silver, and selenium nanoparticles against these parasites. A cross-sectional analysis of 453 O. niloticus specimens revealed an overall EMC prevalence of 40.8%, with infection rates of 34.11% in Giza and 49.5% in Dakahlia. Clinostomid and Prohemistomid metacercariae were the most common, with mixed infections observed. Transmission electron microscopy characterized the synthesized nanoparticles, showing average diameters of 9.6–18.7 nm for chitosan, 13.2–19.8 nm for selenium, and 11.7–15.1 nm for silver nanoparticles. In vitro antiparasitic assays demonstrated varying efficacies among the nanoparticles. Against Clinostomum spp. metacercariae, chitosan nanoparticles showed the highest potency, achieving LC50 at 66 μg/ml after 30 min and LC90 at 100 μg/ml after 120 min. For Prohemistomum vivax EMCs, chitosan nanoparticles exhibited superior efficacy, achieving LC50 at 8 μg/ml after 1 h and LC90 at 16 μg/ml after 2 h. Silver and selenium nanoparticles showed lower efficacy for both parasite species. Scanning electron microscopy revealed significant ultrastructural damage to the parasite tegument following nanoparticle exposure, including disappearance of transverse ridges, integument shrinkage, and formation of blebs. This study provided valuable insights into the prevalence of FBZTs in Egyptian Nile tilapia and demonstrated the potential of nanoparticles, particularly chitosan, as effective antiparasitic agents. These findings pave the way for developing novel, targeted strategies to control fish-borne zoonotic trematodes, potentially reducing their impact on public health and aquaculture economies. [ABSTRACT FROM AUTHOR]

The environmental impact of trace metal contamination is a concern for Lake Small Abaya, Ethiopia, because of nearby agricultural and industrial activities. This study assessed the levels of trace metals (Pb, Zn, Cd, Cu, Fe, Mn, and Cr) in water, sediment, and fish samples, as well as the physicochemical parameters of the water. Samples were collected from five sites and analyzed via graphite furnace atomic absorption spectrometry (GFAAS). The mean concentrations in the water were Zn: 0.6971 mg/l, Fe: 0.5628 mg/l, Cu: 0.1168 mg/l, Mn: 0.2129 mg/l, Pb: 0.0057 mg/l, Cr: 0.0021 mg/l, and Cd: 0.0014 mg/l. In the sediments, the mean concentrations were as follows: Fe, 33.066 mg/kg; Zn, 18.263 mg/kg; Mn, 22.777 mg/kg; Cu, 7.5663 mg/kg; Pb, 0.0751 mg/kg; Cr, 0.0233 mg/kg; and Cd, 0.0183 mg/kg. The fish samples presented mean concentrations of Fe: 21.855 mg/kg, Zn: 12.686 mg/kg, Cu: 0.3185 mg/kg, Mn: 0.9181 mg/kg, Pb: 0.0089 mg/kg, Cd: 0.0075 mg/kg, and Cr: 0.0015 mg/kg. All the metal concentrations were generally below the World Health Organization (WHO) regulatory limits. The physicochemical parameters indicated slightly alkaline to neutral conditions, with electrical conductivity and total dissolved solids within acceptable ranges. These findings suggest that current agricultural and industrial activities do not significantly contribute to trace metal pollution. However, continued monitoring and pollution control measures are recommended to ensure the long-term health and sustainability of the lake. This study highlights the importance of effective environmental management strategies to safeguard this crucial aquatic resource. [ABSTRACT FROM AUTHOR]

The aquaculture industry has been growing rapidly over the past few decades to meet future animal protein demands. However, intensive aquaculture industry faces challenges such as growth abnormalities, high mortality rates, water quality and intestinal health deterioration. Administering probiotics can serve as a nutritional strategy to enhance the immune system and growth performance of fish influxes of gut microbiota. This study aimed to evaluate the impact of two dietary probiotic strains L. mesenteroides and L. lactis on the growth performance, immunity, and gut microbiota of Nile tilapia (Oreochromis niloticus). Fish were fed with basal and experimental diet supplemented by both L. mesenteroides and L. lactis bacteria at 106 cell/g for 8 weeks. Feeding a combination of L. mesenteroides and L. lactis resulted in significant improvements in feed utilization parameters (PER and FER) (P < 0.001), alternative complement pathway activity, intestinal lactic acid bacteria count (P < 0.012), mucus secretion (P < 0.002) and peroxidase activity (P < 0.001) compared to the control groups. Serum lysozyme activity also exhibited a significant increase in the L. mesenteroides and L. lactis dietary group (P < 0.011) compared to the control and single probiotic supplemented diet groups. Furthermore, Nile tilapia fed the L. mesenteroides and L. lactis supplemented diet showed enhanced growth performance metrics (weight gain, final weight and specific growth rate) compared to those fed control and single probiotic supplemented diets (P < 0.022). Additionally, superoxide dismutase activity was significantly elevated in the L.mesenteroides and L. lactis supplemented diet groups compared to the control and single L.mesenteroides supplemented diet groups (P < 0.017). These findings strongly indicate that a dietary combination of L. mesenteroides and L. lactis probiotics could function as a beneficial immunostimulant feed supplement in Nile tilapia aquaculture. [ABSTRACT FROM AUTHOR]

Sex identification and the selection of monosex male tilapia are crucial for tilapia aquaculture. In this study, we evaluated the application of ultrasonography as an alternative procedure for sex identification and reproductive assessment in Nile tilapia (Oreochromis niloticus). Ultrasonography was performed on 23 fish weighing 232-1,281 g to capture longitudinal and transverse images of the ovaries and testes. Female tilapia were identified by the presence of numerous small egg granules and gray or light gray ovarian tissue and male tilapia by the homogeneous echogenicity and uniform gray tubular appearance of the testes. These distinct echogenic patterns allowed for accurate differentiation between the female and male fish. Ultrasonography achieved a 95% accuracy in sex identification, with minimal stress to the fish during the procedure, compared to manual sex sorting, which demonstrated an accuracy of 87%. Furthermore, the method facilitated the assessment of the reproductive status of the fish, including the maturation stages and fecundity potential. The use of ultrasonography offers significant advantages over traditional methods, such as animal welfare enhancements and improved breeding program efficiency. Our findings support the integration of ultrasonography into aquaculture practices and will promote sustainable and humane fish farming while optimizing reproductive management and productivity. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterium that is widely distributed in aquatic environments and causes major economic losses in fish and public health hazards.This study aimed to identify the occurrence of P. aeruginosa in samples collected from fish and fish handlers, and to investigate the antimicrobial susceptibility, virulence determinants, and biofilm genes of P. aeruginosa isolates. A total of 276 samples were cross-sectionally collected from Nile tilapia (53), Golden grey mullet (52), Mediterranean horse mackerel (50), Striped red mullet (71), and fish handlers (50) at five different retail fish markets in Damietta Governorate, Egypt. Pseudomonas species (spp.) were biochemically identified in 57.9% of the total examined samples. Peudomonas aeruginosa were the most prevalent species isolated from the fish and human samples via PCR technique. Peudomonas aeruginosa isolates exhibited full resistance (100%) to tobramycin (TOB), gentamicin (CN), and colistin (CL), with a high level of susceptibility (88.5%) to imipenem (IPM) using the disk diffusion method. Most P. aeruginosa isolates (84.6%) exhibited drug resistance, with 61.5% were multidrug resistance (MDR) and 23.1% were extensive drug resistance (XDR). Most isolates had at least four virulence-associated genes (lasB, toxA, exoU, and oprL) and three biofilm genes (psIA, peIA, and lasR) by using uniplex PCR. The lasI, and rhlR Quorum Sensing (QS) genes were identified in 84.6% and 61.5% in the examined P. aeruginosa isolates, respectively. The highest mortality rate in Nile tilapia experimentally infected with P. aeruginosa isolate encoding most of virulent genes. Multivariate analyses revealed high heterogeneity among the examined isolates. This study revealed the emergence of virulent and drug resistant P. aeruginosa isolates in fish, poses high risks to consumers and food. Thus, strict hygienic measures should be considered when catching, handling, and storing fish, in addition to the routine application of antimicrobial susceptibility testing. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of the proviron, oral anabolic steroid on undifferentiated Nile tilapia (Oreochromis niloticus) larvae sex reversal and to compare its effect with that of 17 α-methyltestosterone. Thus, doses of 25 mg, 50 mg and 75 mg proviron versus 60 mg/kg for 17 α-methyltestosterone were incorporated in the diet of 10-days-post-fertilization old larvae for 28 days. At the end of the treatment and after pre-growth until 90 days post-fertilization, we carried out sexing. Results displayed male rates ranged from 65.7 ± 3.1% to 96.7 ± 1.1% for treatments with 25 mg and 75 mg proviron, respectively and was 99 ± 0.1% for that with 17 α-methyltestosterone. However, no significant difference (p > .05) was found between the average male rate of larvae fed the feed containing 75 mg of proviron and that of larvae fed the feed that containing 17 α-methyltestosterone. [ABSTRACT FROM AUTHOR]

The use of nutraceuticals in aquaculture is getting attention to minimize oxidative stress and increase immunity of aquatic animals. In our experiment, we tested the potency of Phyllanthus niruri, as a stress-reducing and immune-stimulating agent in Nile tilapia, Oreochromis niloticus. We reared fish in a recirculating system for 90 days at low (5 g/L) and high (30 g/L) densities. We fed half of the low and high-density fish with commercial feed (control feed) and the other half, with 5% Phyllanthus niruri incorporated into commercial feed (supplemented feed). We assessed plasma cortisol, blood glucose, packed cell volume, plasma proteins, phagocytic capacity, respiratory burst activity, and lysozyme activity. None of these parameters showed any significant difference among the experimental groups. Based on our findings, we conclude that Phyllanthus niruri does not have any potential role in modulating stress and immune response in fish as a nutraceutical. [ABSTRACT FROM AUTHOR]

ABSTRACT Recent years have witnessed a remarkable global surge in fish production, with Nile tilapia (Oreochromis niloticus) emerging as a prominent contributor owing to its high demand as a nutritious food source. However, unlike terrestrial species, maintaining genealogical control and collecting phenotypic data in fish farming poses significant challenges, necessitating advancements to support genetic improvement programmes. While conventional methods, such as body measurements using rulers and photographs are prevalent in data collection, the potential of ultrasound—a less invasive and efficient tool for fish measurement—remains underexplored. This study assesses the viability of ultrasonography for genetically selecting carcass characteristics in Nile tilapia. The investigation encompasses data from 897 animals representing 53 full‐sib tilapia families maintained in the genetic improvement programme at the Federal University of Lavras. To measure carcass traits, the animals were sedated with benzocaine and ultrasound images were obtained at three distinct points. Subsequently, the animals were euthanised through medullary sectioning for further carcass processing. After evisceration, filleting and skinning, all weights were meticulously recorded. (Co)variance components and genetic parameters of the measured traits were estimated using the Bayesian approach by Gibbs sampling implemented in MTGSAM (Multiple Trait Gibbs Sampling in Animal Models) software. Heritabilities estimated for the studied carcass traits were moderate, ranging from 0.23 to 0.33. Notably, phenotypes derived from ultrasound images demonstrated substantial genetic correlations with fillet yield (0.83–0.92). In conclusion, this study confirms that indirect selection based on ultrasound images is effective and holds promise for integration into tilapia breeding programmes aimed at enhancing carcass yield. [ABSTRACT FROM AUTHOR]

Simple Summary: Aquaculture production has recently surpassed wild fish capture, a growth largely driven by the intensification of fish farming. However, this rapid expansion increases the risk of disease outbreaks and impairs growth performance. These adverse effects can be mitigated through the use of functional additives, such as minerals, vitamins, and industry byproducts with immunomodulatory properties. In this context, we evaluated the effects of functional diets supplemented with vitamins C and E, zinc, and orange peel fragments on the health status and growth performance of juvenile Nile tilapia under stress conditions. The results of this study showed that orange peel fragments, in combination with vitamins C and E, and zinc, produced synergic effects on the immune and antioxidant responses of Nile tilapia subjected to stress. These findings suggest that this supplementation could be an effective nutritional strategy to mitigate the adverse effects of intensive fish farming. This study aimed to evaluate the effect of dietary orange peel fragments (OPFs) enriched with vitamins C (C) and E (E), as well as zinc (Zn) on the growth performance, hematological profile, immunological parameters, antioxidant capacity, and fillet lipid peroxidation of Nile tilapia subjected to heat/dissolved oxygen-induced stress (HDOIS), transport-induced stress (TIS), and Aeromonas hydrophila infection (BC). A group of 500 male Nile tilapia (2.7 ± 0.03 g) was randomly distributed in twenty-five 250 L aquaria (20 fish/aquarium) and fed diets containing OPFs (6 g kg−1), OPFs/C (6 g kg−1/1.8 g kg−1), OPFs/E (6 g kg−1/0.4 g kg−1), OPFs/Zn (6 g kg−1/0.21 g kg−1), or OPFs/C/E/Zn (6 g kg−1/1.8 g kg−1/0.4 g kg−1/0.21 g kg−1) for 100 days. The diets were formulated to contain 30% crude protein and 17 MJ kg−1 gross energy. After the feeding period, three groups of fish were independently subjected to a different type of stress: HDOIS (34 °C) for two days; TIS for four hours, or BC for 15 days. The hematological profile, antioxidant capacity, and fillet lipid peroxidation were determined before and after all the stress treatments, along with immunological parameters, which were investigated only for the fish subjected to bacterial infection. In summary, the results showed that growth was not affected by the OPFs, nor by the OPFs enriched with C, E, and Zn; bacterial infection determined anemia for the fish fed any of the experimental diets; the OPFs did not prevent lipid peroxidation under TIS and BC; on the other hand, when enriched with C/E/Zn, lipid peroxidation decreased under HDOIS and TIS. In conclusion, the OPFs enriched with C/E/Zn showed a synergistic effect that promoted an increase in antioxidant enzyme activity, a decrease in lipid peroxidation, and the maintenance of the hematological profile under HDOIS and TIS, but they were not able to maintain the health status under BC. [ABSTRACT FROM AUTHOR]

Simple Summary: This study compared the growth and meat quality of juvenile male and female Nile tilapia. Males grew bigger and heavier, while females excelled in feed conversion. Males had more crude fat and ash, but moisture and protein levels were unchanged. Amino acid profiles were similar overall, though females had an advantage in non-essential amino acids. This study compared the growth and flesh quality of juvenile male and female Nile tilapia grown in separate RAS tanks. The Genetic Sex Determination method yielded 40 males and 40 females. Males grew longer and heavier than females, and the results showed significant variation between the sexes in terms of weight gain rate (WGR), specific growth rate (SGR), and final body length and weight. In terms of the feed conversion ratio (FCR), Gonad Somatic Index (GSI), and Viscera Somatic Index (VSI), females presented better results than males. Male and female Hepatosomatic Index (HSI) values did not differ significantly—no difference in blood serum values. The meat's moisture and crude protein composition did not alter significantly from male to female; however, the crude fat and ash levels did differ significantly. Male and female animals were given the same seventeen distinct types of amino acids, and there was no distinct variation in the profiles of total amino acids (TAAs) and essential amino acids (EAAs) between the sexes. However, in the non-essential amino acid (NEAA) category, there were marginally significant differences, wherein females performed better than males. Males and females differed considerably in crude fat and ash levels but not in the moisture content or crude protein composition of the meat. Regarding fatty acids, males outperformed females in terms of total fatty acids (TFAs), polyunsaturated fatty acids (PUFAs), and saturated fatty acids (SFAs). However, no significant difference in the amount of monounsaturated fatty acids (MUFAs) in muscle was found between males and females. [ABSTRACT FROM AUTHOR]

This research evaluated the efficacy of mixed Bacillus strains probiotic supplements in mitigating acute thermal-induced stress in Nile tilapia (Oreochromis niloticus). Three experimental fish groups involved 135 Nile tilapia (49 ± 2 g); one control (no added probiotics), 0.5, and 1% of selected Bacillus strains (B. subtilis, B. licheniformis, and B. pumilus) for 58 days. After the feeding period, growth parameters, immunological parameters, stress biochemical markers, and antioxidant parameters in addition to genes related to stress and histopathological changes in fish, were assessed; subsequently subjected to heat shock at 36 ± 0.5 ◦C for 2 h. Before the heat challenge, our results exhibited a marked increase in the growth efficacy (P < 0.05), lower marked serum levels of triglycerides and cholesterol, and tissue malondialdehyde (MDA) levels along with significantly increased superoxide dismutase (SOD) and catalase (CAT) enzymes activity in fish-fed Bacillus probiotic at 0.5% concerning the control group (P < 0.05). There were no significant changes in the serum levels of glucose, cortisol, lactate, phagocytic activity, respiratory burst (ROS), total immunoglobulin Ig, alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), total protein, albumin, globulin, uric acid, urea, creatinine, as well as HSP70, GST, and GPx mRNA expression in most of the probiotic groups compared to the control group (P > 0.05). When Nile tilapia was exposed to heat stress, supplementation with Bacillus probiotic in the diet significantly decreased most of the indices related to serum biochemical (ALT (P < 0.01; P < 0.001), AST (P < 0.01), LDH (P < 0.01), urea (P < 0.05), and creatinine (P < 0.01)), triglycerides (P < 0.001; (P < 0.01)), cholesterol (P < 0.01; (P < 0.05)), glucose (P < 0.001), and cortisol (P < 0.01; (P < 0.05)), with tissue oxidative stress MDA levels (P < 0.05), and HSP70 mRNA expression (P < 0.01; P < 0.001), aligned with the stressed control group. In addition, a notable upsurge in the total protein, albumin, globulin, phagocytic and ROS activities, and total Ig, as well as the enzymatic antioxidant ability (SOD, CAT) (P < 0.01), with GST and GPx mRNA expression (P < 0.05; P < 0.01), were shown in fish-fed Bacillus spp. post-exposure compared with the stressed control group. Besides, no histopathological alterations were revealed in the spleen and brain of fish pre- and post-heat exposure. According to our findings, diet supplementation of Bacillus species has the potential to combat the suppressive effects of heat shock in Nile tilapia. Highlights: • Heat exposure altered the phagocytic activity, ROS, and total Ig and hepatic and liver biomarkers. • Heat exposure induced oxidative damage and pathological alterations of different tissues. • Heat exposure enhanced the expression of HSP70 in the head kidney of tilapia. • Mixed Bacillus spp., a dietary probiotic, effectively mitigated these heat-induced toxicity. [ABSTRACT FROM AUTHOR]

Rationing aquaculture farming feed is challenging for producers due to high feed costs, representing 30%–60% of the total operating costs. Therefore, optimal timing of feeding could lead to improved economic returns from an aquatic system. An optimal dynamic feeding model has been determined considering the von Bertalanffy growth model. A bioeconomic model of tilapia production in Mexico for specific markets was used for numerical illustration. The von Bertalanffy growth model was parameterized with experimental data from tilapia (Oreochromis niloticus) fed four ration sizes (50%, 80%, 100%, and satiety), in order to determine different optimal rationing for different fish sizes (200, 300, and 400 g), market prices (Monterrey, Cancún, Mexico City, and On site), and optimal harvesting times (OHT), considering the time value of money. The results of the modeled optimal feeding trajectories show a continuous decrease from stocking to reach a minimum value and then slightly approaching the harvest size. This result contrasts with the recommendations of the feed suppliers and with those found when a potential growth model was used. The results in the case study showed that the Monterrey market presented the highest present value of the benefits in the OHT and the different market sizes. The implications of the Bertalanffy model for optimal rationing trajectories are presented in the discussion. [ABSTRACT FROM AUTHOR]

Background: Streptococcus agalactiae (Group B streptococcus, GBS) induces a serious infection that can harm not only aquatic life but also humans and other animals. In a fish farm in southern Egypt, Nile tilapia (Oreochromis niloticus) has developed an epidemic with clinical symptoms resembling piscine streptococcosis. Results: Initial microscopic inspection of the affected fish brain and kidney indicated the presence of Gram-positive cocci. S. agalactiae was effectively isolated and identified using nucleotide homology of the 16S rRNA and species-specific PCR. The partial 16S rRNA sequence was deposited in the GenBank database at the NCBI and given the accession number MW599202. Genotyping using RAPD analysis indicated that the isolates in the present study belonged to the same genotypes and had the same origin. The challenge test, via immersion (9.2 × 107, 9.2 × 106, and 9.2 × 105 CFU/ml for 1 h) or intraperitoneal injection (4.6 × 107, 4.6 × 106, and 4.6 × 105 CFU/fish), elicited clinical symptoms resembling those of naturally infected fish with a mortality rate as high as 80%. The ability to create a biofilm as one of the pathogen virulence factors was verified. Zinc oxide nanoparticles and the ethanolic leaf extracts of nine medicinal plants demonstrated considerable antibacterial activities against the tested S. agalactiae strain with low minimum bactericidal concentrations (MBC) and minimum inhibitory concentrations (MIC). The ethanolic leaf extracts from Lantana camara and Aberia caffra showed potent antibacterial activity with MBC values of 0.24 and 0.485 mg/ml, and MIC values of 0.12 & 0.24 mg/ml, respectively. Conclusion: This study isolated S. agalactiae from O. niloticus mortalities in a fish farm in Assiut, Egypt. The pathogen persists in fish environments and can escape through biofilm formation, suggesting it cannot be easily eliminated. However, promising findings were obtained with in vitro control employing zinc oxide nanoparticles and medicinal plant extracts. Nevertheless further in vivo research is needed. [ABSTRACT FROM AUTHOR]

Background: Saline-alkaline water aquaculture has become a key way to mitigate the reduction of freshwater aquaculture space and meet the increasing global demand for aquatic products. To enhance the comprehensive utilization capability of saline-alkaline water, it is necessary to understand the regulatory mechanisms of aquatic animals coping with saline-alkaline water. In this study, our objective was to elucidate the function of proline metabolism in the alkaline adaptation of Nile tilapia (Oreochromis niloticus). Results: Expose Nile tilapia to alkaline water of different alkalinity for 2 weeks to observe changes in its growth performance and proline metabolism. Meanwhile, to further clarify the role of proline metabolism, RNA interference experiments were conducted to disrupt the normal operation of proline metabolic axis by knocking down pycr (pyrroline-5-carboxylate reductases), the final rate-limiting enzyme in proline synthesis. The results showed that both the synthesis and degradation of proline were enhanced under carbonate alkalinity stress, and the environmental alkalinity impaired the growth performance of tilapia, and the higher the alkalinity, the greater the impairment. Moreover, environmental alkalinity caused oxidative stress in tilapia, enhanced ion transport, ammonia metabolism, and altered the intensity and form of energy metabolism in tilapia. When the expression level of the pycr gene decreased, the proline metabolism could not operate normally, and the ion transport, antioxidant defense system, and energy metabolism were severely damaged, ultimately leading to liver damage and a decreased survival rate of tilapia under alkalinity stress. Conclusions: The results indicated that proline metabolism plays an important role in the alkaline adaptation of Nile tilapia and is a key regulatory process in various biochemical and physiological processes. [ABSTRACT FROM AUTHOR]

This study investigated the effects of integrating various fish species in a rice field co-culture system on water quality and soil properties. The species included common carp (Cyprinus carpio), Nile tilapia (Oreochromis niloticus), silver barb (Barbonymus gonionotus), snakeskin gourami (Trichopodus pectoralis), and giant freshwater prawn (Macrobrachium rosenbergii). The key water quality parameters measured included water temperature, dissolved oxygen, pH, transparency, ammonia, and nitrite. Soil properties were evaluated through pH, electrical conductivity, organic matter, nitrogen, phosphorus, and potassium. All the selected aquatic animals showed high adaptability in co-culture systems, with survival rates exceeding 80%. Additionally, rice yields increased by approximately 16%, with the highest yield observed in plots stocked with prawns. The results indicated that the presence of aquatic animals enhanced nutrient cycling, leading to significant improvements in both water quality and soil fertility. Differences in water quality and soil properties throughout the culture period were specific to the species present. These findings suggest that rice-fish co-culture systems serve as an effective nature-based solution for enhancing productivity, sustainability, and food security. [ABSTRACT FROM AUTHOR]

Lowering nanoparticles (NPs) toxicity before discharge into aquatic environments and employing agricultural waste materials for environmental sustainability are necessary nowadays. Since this has never been done, this work examines how green CuO NPs treated with rice husk (RH) as a bio-adsorbent may be safer for Nile tilapia (Oreochromis niloticus) than chemically manufactured ones. So, five groups of fish were randomly placed in glass aquaria. One group was a control, and four groups received 50 mg/L green and chemically produced CuO NPs (GS and CS) with and without RH for 24, 48, and 96 h. RH was collected from all groups, and the results showed GS-CuO NPs had a greater adsorptive capacity than CS-CuO NPs after all time intervals. After analyzing fish indicators in all groups compared to the control, higher Cu bioaccumulation was exhibited in the liver and gills. The liver and gills showed elevated levels of glutathione peroxidase (GPx), catalase (CAT), and thiobarbituric acid reactive substances (TBARS), while the levels of glutathione reduced (GSH) were significantly lower. In addition, Cu exposure impaired liver and gill histology. Finally, our results indicated that using RH as an adsorbent for CuO NPs after their green synthesis instead of chemical synthesis before they enter the aquatic environment can enhance the overall health of fish and environmental sustainability. [ABSTRACT FROM AUTHOR]

Background: Hypoxia stress resulted in mortality during the fish aquaculture program, affecting the sustainable development of the aquaculture industry. The Egyptian strain of O. niloticus showed a strong ability to hypoxia. In this study, a Nile tilapia strain that was kept and selected for 45 years by the author's team was used to elucidate the mechanism of the hypoxia response in the liver, including the identification of metabolic pathways and genes, involved in the hypoxia response of this strain. Results: The effects of hypoxia stress were detected at 0-hour, 6-hour, and 72-hour time points (0 h, 6 h, 72 h) on tilapia liver at 1 mg/L dissolved oxygen conditions. The blood triglyceride, blood glucose and cholesterol values exhibited significantly different change trends, but the hemoglobin content showed no significant differences between 0 h, 6 h and 72 h (P > 0.05). The activities of catalase (CAT), glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), lactate dehydrogenase (LDH), and acid phosphatase (ACP) in the liver tissue gradually increased at 0 h, 6 h and 72 h (P < 0.05). Histological analyses revealed structural changes in intracellular lipid droplets, nuclear migration and dissolution, and cell vacuolization in liver tissues. Six pathways were identified as the main enriched metabolic pathways according to the transcriptome profiling analysis, which were protein processing in endoplasmic reticulum, steroid biosynthesis, peroxisome, PPAR signaling pathway, glycolysis/gluconeogenesis and Insulin signaling pathway. The expressions of the important differentially expressed genes were verified by qPCR analysis, including erola, LOC100692144, sqle, cratb, pipox, cpt1a2b, hik and acss2l, ehhadh, prkcz, fasn and plaa, which showed the same expressions trends as those of RNA-Seq. Conclusions: The Nile tilapia strain improves the abilities of hypoxia response through energy metabolism. Antioxidant enzyme measurements in the liver indicate that these five antioxidant enzymes play important roles in protecting the body from hypoxic damage. The histological changes in liver cells indicate that the damage caused by hypoxia stress. The immune-related metabolic pathways and energy metabolism-related pathways were obtained by transcriptome profiling, and these metabolic pathways and the differentially expressed genes selected from these metabolic pathways may be involved in the mechanism of hypoxia tolerance in this strain. These findings provide a better understanding of the hypoxia response mechanism of fish, and represent a useful resource for the genetic breeding of O. niloticus. [ABSTRACT FROM AUTHOR]

Fish feed is critical in aquaculture production, accounting for over 60% of operational costs, with protein being the most expensive component. Traditionally, fish meal (FM) has been the primary protein source. However, due to declining capture fisheries and high demand, FM has become scarce and costly, necessitating the search for alternative, low‐cost, and nutritionally balanced protein sources. A 180‐day feeding experiment was conducted to evaluate the effects of replacing FM with a combination of cottonseed and sunflower meal (SFM) in Nile tilapia diets on growth performance, protein digestibility, and economic returns. Freshwater shrimp meal was replaced at 25%, 50%, 75%, and 100% (diets D1, D2, D3, and D4) and compared to the control diet (D0) containing only FM. Monosex Nile tilapia fingerlings (25 ± 0.01 g) were allocated to 15 cages within an 800 m2 earthen pond. Fish on diets D0 and D1 showed superior growth performance metrics, including final mean body weight, weight gain, daily weight gain, specific growth rate, feed conversion ratio, and survival rate (p > 0.05), compared to diets D2, D3, and D4. Growth performance declined significantly with increasing levels of the plant protein mixture (p < 0.05). Diet D0 had the highest apparent protein digestibility, while D4 had the lowest. Cost‐benefit analysis revealed that diet D0 had the highest production cost, followed by diets D1, D2, D3, and D4, with no significant cost difference between D0 and D1 (p > 0.05). Thus, the plant protein mixture can effectively replace FM at a 25% inclusion level in Nile tilapia diets. [ABSTRACT FROM AUTHOR]

This study aimed to conduct a multidisciplinary investigation integrating detailed morphology, molecular characterization, water parameters, histopathology alteration, and the trials of treatment of Clinostomum spp. In this study, 300 Nile tilapia (Oreochromis niloticus) were collected from the farmed and wild Nile River at Al Bahr Al Aazam, Giza Governorate to assess Clinostomid infection prevalence. Fish and water samples were collected from private fish farms, and water drains at Dakahlia, and Giza, Egypt. Analysis of the water revealed inadequate water quality, particularly in the fish farms. Snails and piscivorous birds were abundant at fish collection sites. The recovered Clinostomid MCs morphological characteristics and COI gene sequence analysis identified them as Clinostomum complanatum, C. phalacrocoracis, and Euclinostomum heterostomum. Clinostomid MCs disturbed the fish's hematological and biochemical blood parameters. Bath treatment of parasitized fish with praziquantel (2 mg/L for 24 h) revealed a significant reduction in the number of vital MCs vs. infected fish (non-treated). Praziquantel (PZQ) is an effective and safe therapy for controlling Clinostomid infections affecting farmed Nile tilapia. The current findings indicate a link between poor environmental conditions and Clinostomum infections in tilapia. The study highlights the impacts of Clinostomid MCs on fish health and recommends bath treatment with PZQ as an efficient control method for these dangerous parasites to protect human and fish health. [ABSTRACT FROM AUTHOR]

Nile Tilapia (Oreochromis niloticus) is the most widely cultivated freshwater fish because it can grow well in tropical countries and temperate regions. This research aims to create artificial feed that matches the nutritional parameters needed by nile tilapia. This artificial feed will use the basic ingredients of shrimp waste, with addition of oilcake, bran, starch flour, vitamins, squid oil, and water. There are four variables used to make artificial feed with different basic and additional ingredients, as well as varied processing techniques. After artificial feed is completed, proximate analysis will be carried out to test composition of crude fiber, carbohydrates, water, fat, ash, and protein using various methods. The test method for the composition of crude fiber, carbohydrates, fat, ash, and protein follows the method set by the Association of Official Analytical Chemists (AOAC). Based on the results of proximate analysis, variable 1 (V1) has fulfilled the nutritional content of protein and moisture content needed by nile tilapia. This shows that artificial feed formulations from shrimp waste can be used because protein is an important element for nile tilapia growth, but the content of crude fiber, carbohydrates, fat, and ash exceeds ideal value for nile tilapia nutrition. This also occurs in variables 2, 3, and 4 that have not met nutritional needs, especially protein. However, the composition of artificial feed with shrimp waste and addition of meal, bran, starch flour, vitamins, and water in V1 can be further investigated to reduce the content of crude fiber, carbohydrates, fat, and ash. [ABSTRACT FROM AUTHOR]

The vasa gene, encoding an ATP-dependent RNA helicase, and the nanos-2 gene, an RNA-binding protein, are essential for germ cell origination, migration, maintenance, and development in vertebrates and invertebrates. The expression levels of the vasa and nanos-2 genes have not yet been investigated or reported in crappie species. These two genes were partially sequenced and characterized, and their expression patterns were analyzed using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) according to age and sex. The vasa sequences of white crappie (WC) females and males showed significant similarity with the vasa homologs of largemouth bass (Micropterus salmoides; 93.1–93.98%) and smallmouth bass (M. dolomieu; 91.95–92.77%), indicating its conserved nature within the Family Centrarchidae. The vasa sequence of black crappie (BC) females showed significant similarity with the vasa homologs of white crappie (91.67%), largemouth bass (96.10%), smallmouth bass (96.10%), spotted scat (Scatophagus argus; 97.37%), mandarin fish (Siniperca chutasi; 96.15%), Japanese sea bass (Lateolabrax japonicus; 94.87%), lumpfish (Cyclopterus lumpus; 91.95%), southern bluefin tuna (Thunnus maccoyii; 94.74%), large yellow croaker (Larimichthys crocea; 92.21%), and Nile tilapia (Oreochromis niloticus; 92.21%). The nanos-2 sequences of WC females, WC males, and BC females showed significant similarity with the nanos-2 of largemouth bass (92.92–96.36%), smallmouth bass (92.92–96.36%), and mandarin fish (92.66–94.34%). The expression of vasa in BC females was significantly higher at age-2 than at age-1, while WC males and females presented no significant age-related differences. Neither species had a significant difference in nanos-2 gene expression with age. The expression levels of vasa and nanos-2 were significantly higher in WC males than females. [ABSTRACT FROM AUTHOR]

The effects of three medicinal plants in the feeds of juvenile Nile tilapia (Oreochromis niloticus) were investigated on growth, survival, immunity, and digestive histology at various inclusion levels: (A) Guiera senegalensis at 0, 1, 2, 4, and 8%; (B) Pluchea odorata at 0, 0.5, 1, 2, and 4%; (C) Piliostigma reticulatum at 0, 1, and 2%; and (D) a mixture of the three at 0, 1, and 2%. After 28 days of feeding, fish were infected with Aeromonas hydrophila for 12 days. The results showed that, except for G. senegalensis, the inclusion of the medicinal plants, alone or combined, enhanced the immune response. The diet with 4% P. odorata significantly increased plasma lysozyme and bactericidal activities without affecting feed conversion efficiency or growth. Despite improved immunity, none of the treatments enhanced post-infection survival rates. However, fish fed the 1% mixture showed healthier livers and intestines, with reduced cell swelling and normal lipid deposits, followed by the 2% mixture and the control. These results highlight the potential benefits of incorporating P. odorata and the plant mixture into the diets of Nile tilapia juveniles for enhancing their immune response against A. hydrophila. [ABSTRACT FROM AUTHOR]

While chitosan is widely used in aquaculture feed, chitosan nanoparticles (CNPs) offer potential advantages due to their enhanced absorption. This study investigated the safe use of CNP levels in Nile tilapia feed, evaluating its impact on growth, immunity, and disease resistance. Five experimental diets were formulated and supplemented with zero chitosan (served as a control group), 1g/kg of chitosan (CS), and 1, 3, and 5 g/kg of CNPs. Each diet was randomly assigned to three replicate groups of 45 fish per group (15 fish/tank) with an average weight of (42.10 ± 0.05g, mean ± S.E.) twice daily (09:00 a.m. and 4:00 p.m.) to apparent satiation for two months. At the end of the feeding trial, fish fed 5 g/ kg of CNPs had the highest growth performance. However, no significant variations (p > 0.05) in somatic index were seen between the experimental groups. All chitosan and CNP-enriched groups exhibited improved intestinal morphology compared to the control group, characterized by increased villus length and width, reduced necrosis of intestinal tips, and better overall tissue integrity, with the CNP 3g and 5g groups demonstrating the most favorable intestinal structure. The CNP-treated groups (3, 5 g/kg) had significantly higher blood indices and serum globulin. Malondialdehyde (MDA) levels were lower in the CNP-treated groups compared to the chitosan macromolecule group. There was a substantial rise in glutathione (GSH), total antioxidant capacity (TAC), phagocytic index, and respiratory burst activity in the 5 g/kg CNP-treated group. The dietary addition of 5 g/kg of CNPs raised mRNA expression for TLR-2, MUC-2, and IGF-1, but there was no significant difference in HSP70 expression across treatments. After the experimental challenge with Aeromonas veronii biovar sobria, the groups that received 3 and 5 g/kg of CNPs exhibited the lowest mortality rates. Overall, the results suggest that including 5g/kg of CNPs in fish food is safe and effective for enhancing their health and growth, making it a promising addition to aquaculture feed. [ABSTRACT FROM AUTHOR]

Microalgae are promising as prebiotics in aquaculture. Arthrospira maxima has potential nutritional value but is poorly studied. We assessed A. maxima feed supplementation in tilapia fry and evaluated its effect on growth performance and gut microbiota. Fish were cultivated in ponds under 0%, 5%, 10%, and 15% A. maxima inclusion treatments. Growth parameters and biomass proximate analysis were assessed. A meta-amplicon analysis was performed on the gut microbiota using DADA2 and PICRUST2 for functional prediction. Among treatments, the 5% supplementation group seemed to present no negative effect on growth parameters and did not compromise the nutritional quality of tilapia fry biomass. Microbial composition was characterized by Cetobacterium, Pseudomonas and Aeromonas genera, and a predominance of beneficial metabolic pathways. Microbiota of tilapia fry fed with A. maxima showed unique genera with reported beneficial functions in tilapia. The abundance of potential pathogenic taxa was significantly decreased in supplementation treatments, possibly related to valuable compounds of A. maxima. The inclusion of the microalgae supported the stability of the microbiota, favoring the growth of commensal species. This seems to have an effect on decreasing the presence of pathogenic genera in the gastrointestinal tract. Overall, our work proposes 5% feed inclusion of A. maxima to be the most suitable for tilapia fry aquaculture to maintain production rates while improving general health. [ABSTRACT FROM AUTHOR]

The main objective of the present trial was to examine the efficacy of feeding tilapia fry fish on Artemia franciscana diets supplemented with various oil emulsion resources in terms of performance, behavior indices, survival rate, blood biochemical parameters, and immunological response. Four hundred Nile tilapia fry (weighing 0.15±0.05 g and measuring 2.17±0.08 cm) were randomly allocated into four equal groups (each with five repetitions) and acclimatized for fifteen days. The first group served as the control and received unenriched Artemia franciscana (G0), while the remaining three groups were fed Artemia franciscana diets enriched with different oil resources (0.5 mL oil per liter for 6 hours): soybean oil (G1), sesame oil (G2), and rice bran oil (G3). Behavioral observations were recorded during the 45-day experimental period. At the end of the feeding trial, the chemical composition and fatty acid content of both Artemia and fingerlings were analyzed. Furthermore, the growth performance, survival, and immune response of the fingerlings were evaluated. The results indicated noticeable improvements in behavioral measurements (feeding, foraging and schooling), performance (final length, final weight, net weight gain, feed conversion ratio and specific growth rate), survival, and immune response among fry fish supplemented with enriched Artemia, particularly those enriched with soybean oil. Additionally, the chemical composition and fatty acid content of both Artemia and fish fry were significantly enhanced when oil emulsions are applied, with soybean oil demonstrating the most prominent improvements. Whereas, supplementing fry fish Artemia diets with oil resulted in lower liver enzyme activity and higher protein component levels in plasma in comparison to the control group. In brief, feeding Nile tilapia fry fish Artemia diets enriched with a soybean oil emulsion (0.5 mL/L) is recommended for promoting high performance, immunological activity, and survival throughout the early stage till fingerlings phase. [ABSTRACT FROM AUTHOR]

In this study, we described immediate/acute reactions to stress-related chemical cues (SC – Stress Cue) in fish. Specifically, we evaluated the effects of SC on ventilation rate (VR) and feeding behavior in Nile tilapia (Oreochromis niloticus), a highly relevant species for world aquaculture, therefore, to understand the diversity of stressful contexts and stress responses in this species have important practical applications (stress reduction). Stress cue was obtained from conspecifics exposed to a handling stressor. Stress was confirmed by measuring plasma cortisol levels. The responses to SC were contrasted to chemical control cues: a cue originated from non-stressed conspecifics and pure water (vehicle control). We observed that Nile tilapia exposed to SC had an increase in VR, but without effects on feeding behavior (feeding latency and ingestion). Thus, the SC is a stressor that induces readily stress response (VR increase), suggesting sympathetic activation, but did not change feeding performance. In practical terms, it is positive because although social propagation of stress via SC elicits a stress response, it did not harm appetite. [ABSTRACT FROM AUTHOR]

Aeromonas veronii, a threatening fish pathogen, is implicated in food-borne infections in humans, contributing to substantial economic losses in the aquaculture sector. To examine the occurrence, resistance profiles, 16SrRNA sequence analysis, virulence-determinant and resistance genes, and pathogenicity of A. veronii isolated from Nile tilapia (Oreochromis niloticus), almost 150 fish weighing 75 ± 10 g (apparently healthy; n = 50 and moribund fish; n = 100) were collected from commercial farms in Ismailia Governorate, Egypt. Subsequently, the clinical, post-mortem, and bacteriological examinations were carried out. The overall prevalence of A. veronii in the collected O. niloticus was 18.6% (28/150), where the pathogen was only detected in the moribund one. Phylogenetic analysis revealed that the tested isolate exhibited significant genetic identity with other strains from diverse locations and origins in China and Egypt. PCR showed that aerA (95.4%) was the most predominant virulence gene associated with A. veronii isolates retrieved from O. niloticus, followed by hly (80.3%), ast and ser (69.7% for each), and alt (50.1%). Moreover, 40.9% of the obtained isolates were extensively drug-resistant (XDR) to seven classes and inherited blaTEM, tetA, blaCTX-M, and sul1 genes. Besides, 6.1% of the recovered isolates were carbapenem-resistant and XDR to seven classes harboring blaTEM, blaNDM, blaCTX-M, sul1, and tetA genes. The cumulative mortality rate was 86.7% in the fish group injected with a virulent A. veronii strain at a concentration of 3 × 108 CFU/mL. Concisely, this study underscored the existence of XDR A. veronii in O. niloticus specifying a public health hazard. XDR A. veronii isolated from O. niloticus commonly inherited aerA, ast, ser, and alt virulence-determinant genes and blaTEM, sul1, blaCTX-M, and tetA resistance genes. [ABSTRACT FROM AUTHOR]

The purpose of the current study was to assess the effect of dietary supplements of either aqueous (AE) or ethanolic (EE) (Juniperus communis) leaf extracts on growth performance, intestinal health, hemato-biochemical indices, antioxidant, inflammation cytokine responses, and resistances against infection in Nile tilapia, Oreochromis niloticus. Fish groups were controlled with no extract (J1) and fed diets (J2, J3, J4, and J5) containing 1.0 and 2.0 g/kg aqueous and ethanolic extract for 60 days. Fish were given an intraperitoneal injection (IP) of Aeromonas hydrophila for 10 days after the feeding trial; then, the fish mortality was recorded. Growth, feed efficiency, and activity of endogenous enzymes (lipase, trypsin, chymotrypsin, and amylase) were significantly improved in all dietary J. communis groups, especially in J5, compared to other groups. Also, J5 showed the highest absorption area, muscularis, goblet cells, villi width, and fewer gut bacterial counts than the other groups. In addition, the J4 and J5 groups of tilapia fish exhibited a significant increase in the levels of total protein, serum albumin, globulin, hemoglobin, white blood cells, and hematocrit (P < 0.05), as well as a significant decrease in the levels of serum alanine, aspartate aminotransferases, glucose, and cholesterol compared to the J1 groups. Moreover, the J4 and J5 fish showed a significant decline in the levels of MDA with improvements in antioxidant (SOD, CAT, and GPX) and immunological (lysozyme, immunoglobulin M, and complement C3) indices compared to the J1 group. Fish in J4 and J5 exhibited downregulated levels of il-8, il-10, il-1β, tnf-α, ifn-γ, and hsp70 genes compared to other groups. In contrast, hepatic catalase (cat), superoxide dismutase (sod), and interleukin (il-10) gene expressions were upregulated. The lowest fish mortality after the bacterial challenge was recorded in the J5 group. These findings suggest that 2.0 g/kg feed ethanolic extract of J. communis-fed Tilapia fish fingerlings improved their growth and intestinal health, boosted their immune systems and antioxidant responses, and increased their resistance to A. hydrophila. [ABSTRACT FROM AUTHOR]

This study evaluates the anesthetic effectiveness and potential reduction of toxicity in Nile tilapia (Oreochromis niloticus) through the use of clove, cinnamon, and tea tree essential oils. We evaluated genetic damage, enzymatic activity, and gene expression. We conducted two experiments. In experiment 1, we individually evaluated the anesthetic efficiency and genotoxicity of these essential oils. In experiment 2, we assessed their combined effects at different concentrations. Clove oil, particularly at the highest concentration (200 µL/L), induced genotoxic effects and oxidative stress in fish, leading to alterations in gene expression regulation and enzymatic activity. Tea tree and cinnamon oils, at concentrations of 75 and 100 µL/L, required longer times to induce fish to the anesthesia stage and were less efficient in achieving deep anesthesia stage. Notably, combining tea tree and cinnamon essential oils to clove oil showed promise as an alternative to using clove oil alone. This combination demonstrated potential as an effective anesthetic and may help mitigate the genotoxic effects associated with clove essential oil. Our findings suggest a viable option to minimize potential physiological damage during the anesthesia process in aquaculture, thereby promoting a balance between this necessary procedure and animal welfare. [ABSTRACT FROM AUTHOR]

Immunosaccharides such as β-glucans and fructooligosaccharide (FOS) strengthen the host's immune responses. This study examined the influences of three levels of the β-1, 3 glucan-FOS combination on Red tilapia performance. Four diets were prepared: T0 as a control, while T0.5, T1, and T1.5 indicate the addition of β-1, 3 glucan-FOS mixture at 0.5%, 1%, and 1.5%, respectively. Then, 240 red Tilapia (Oreochromis niloticus x O. mossambicus) (weight 6.1 ± 0.07gm) were allocated into four groups, and every group was fed tested diets for 56 days. After the feeding trial, growth parameters, erythrogram profile, liver and kidney function testes, glucose, histopathological analysis, and gene expressions for antioxidants, catalase (CAT) and glutathione peroxidase (GPX) besides growth hormone (GH) and insulin-like growth factor 1 IGF1-related markers were assessed. Red tilapia fed T0.5, T1, and T1.5 exhibited consistent growth, survival rate, and homeostasis compared with the control group. Different supplement concentrations displayed varying levels of responses. The hepatorenal biomarkers (alanine transaminase (ALT = SGPT) and aspartate transaminase (AST = SGOT), alkaline phosphatase (ALP = ALK), urea, and creatinine) and glucose showed a significant reduction in the supplemented groups compared with the control, especially in the T1 and T1.5 groups. The intestinal morphometric study revealed that fish group fed on T1 represented the best result, whereas group T1.5, followed by group T0.5, was moderately treated, compared to the control. The real-time quantitative reverse transcription PCR (qRT-PCR) analysis displayed up-regulated expression of antioxidant and growth-correlated genes in the T1.5 groups. After 56 days, the β-1,3 glucan-FOS fed groups also exhibited an increase in survival rates compared to the control when challenged with a pathogenic Vibrio alginolyticus. Current findings suggest that inclusion of β-1,3 glucan-FOS in diets could enhance red tilapia biochemical parameters, growth, and protection against pathogenic V. alginolyticus infection. [ABSTRACT FROM AUTHOR]

Recently, medical plants have been widely used as replacements for antibiotics in disease treatment. Because of its multiple medicinal uses, peppermint (Mentha piperita, MP) is a common herbal remedy. In the present study, MP powder was used as a feed additive to assess growth performance; hematological; biochemical and immune parameters; intestinal histology; and interleukin 1β (IL-1β) gene expression, as well as protection against Vibrio alginolyticus infection in Oreochromis niloticus. O. niloticus (n = 120, 25.66 ± 0.16 g) were fed diets containing 0 (CTR), 2, 3, or 4% MP for 60 days. The results revealed that the inclusion of 2% MP significantly improved the growth indices, intestinal morphological parameters, and reduced the feed conversion ratio. The 2% MP treatment significantly (P < 0.05) increased hematological parameters (red blood cell (RBC) count, white blood cell (WBC) count, packed cell volume% (PCV%), hemoglobin) compared with those of the CTR (P < 0.05). Additionally, feeding fish 2% MP diets decreased the levels of cholesterol and LDL (low-density lipoprotein). There were significant increases in immune responses (serum protein and phagocytic activity and index) and non-significant increases in the expression of IL-1β in the 2% MP group comparing with the other groups and the CTR group (P < 0.05). At the end of the feeding trial (60 days), fish were challenged with a virulent strain of Vibrio alginolyticus and the results showed that the mortality rate decreased in the 2% MP treatment group, followed by the 3% and 4% MP groups. Overall, the results revealed that the dietary inclusion of 2% MP can exhibit growth-promoting and immunostimulant effects for sustainable aquaculture. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of the dietary addition of lavender essential oil (LEO) on mitigating the adverse effects of high stocking densities (HSD) in the Nile tilapia, Oreochromis niloticus. We used 216 fingerlings and randomly distributed them according to a 2 × 3 factorial design, comprising two stocking densities: a low stocking density (LSD, 2.92 kg/m3) and a high stocking density (5.85 kg/m3) and three levels of LEO, 0, 0.5%, and 1%, for 70 days. We evaluated their growth, digestive enzyme activity, blood biochemical parameters, immune/antioxidant indices, and intestinal morphology. All fish were intraperitoneally inoculated with Aeromonas veronii for a bacterial challenge test at the end of the feeding trial and monitored for 14 days. After 14 days, head kidney samples were collected from all fish to assess the level of expression of immune-related and apoptosis-related genes. Additionally, tissue samples were collected from the liver, kidney, and intestine to investigate the immunohistochemistry and histopathological alterations. The results showed that the final body weight and weight gain were lower and the feed conversion ratio was higher in fish cultured under HSD compared to those cultured under LSD. The fish cultured under LSD and HSD had higher final body weight when administered dietary LEO compared to the fish that were fed the non-supplemented diet. Adding 1% LEO increased the intestinal villus height and muscular coat thickness (MT). The MT was lower in fish cultured under HSD compared to those cultured under LSD. The amylase and lipase activities were lower in the fish cultured under HSD than in those cultured under LSD. However, LEO addition increased the lipase activity in fish cultured under LSD and HSD. Fish cultured under HSD showed lower immune/antioxidant indices (lysozymes, nitric oxide, complement 3, catalase, superoxide dismutase, and glutathione-S transferase) than those cultured under LSD. However, LEO addition significantly increased the immune response and antioxidant activity in fish cultured under LSD and HSD (P < 0.01). The level of expression of the IL-1β, IL-6, IL-8, NF-kB, and TLR-4 B genes was upregulated in the LSD + LEO1, LSD + LEO0.5, and HSD + LEO1 groups. The expression of TGF-β and IL-10 was upregulated in fish that received 1% and 0.5% LEO, irrespective of whether they were cultured under LSD or HSD. The level of expression of apoptosis-related genes (caspase 3 and BAX) was upregulated in the HSD + LEO0 group and modified by the addition of LEO in their diet. The immunoexpression of NF-kB and IL-1β after bacterial challenge increased in the tissues of fish cultured under LSD and HSD after LEO was administered. These results indicated that the dietary addition of 1% LEO mitigated the harmful effects of HSD on the growth, immunity, antioxidant activity, and disease resistance of the Nile tilapia. [ABSTRACT FROM AUTHOR]

Legal restrictions and consumer trends are contributing to the growing movement for fish welfare. Therefore, the aquaculture sector is a means of reducing animal stress and enhancing physiological state, which raises financial profits. Feed additives have therefore been suggested as possible dietary stress alleviation. In this trend, a 75-day feeding trial was conducted to evaluate the effects of three organic acids (formic acid (FA), lactic acid (LA), and commercial organic acids mix (COM)) as dietary additives in Nile tilapia (Oreochromis niloticus) reared under a stressful condition (unchanged water). Fish (weighing 3.95 ± 0.05 g) were randomly housed into eight groups (n = 210 fish/group; 70 fish/replicate; 3 replicates/group). The first (negative control) and second (positive control) groups were fed a basal diet without additives and with water exchange at 20% of the water volume every 2 days for the first group and without water exchange for the second. The other six groups (FA1, FA2, LA1, LA2, COM1, and COM2) were fed basal diets supplemented with OAs at two doses (1 and 2%) without water exchange during the trial. The results revealed that fish kept without water exchange (positive control) had the highest level of water-unionized ammonia and nitrite and a marked decline in growth performance (weight gain and specific growth rate). The unchanged water induced substantial decreases in the hematological profile (white and red blood cell count, hemoglobin value, and hematocrit %), protein profile indices (total protein, albumin, and globulin), and antioxidant-immune response (superoxide dismutase, catalase, lysozyme, and total immunoglobulin M). In addition, the biochemical indices (glucose, creatinine, urea, alanine aminotransferase, and aspartate aminotransferase) and lipid peroxide (malondialdehyde) were substantially increased in the positive control group. In addition to that, marked and severe histopathological alteration in the gills, liver, and intestine including hyperplasia, hemorrhage, and degenerative and necrotic changes that were associated with desquamation and sloughing were obvious in the PC group. Dietary LA1 significantly enhanced (P < 0.05) the overall measured indices; meanwhile, the dietary FA and COM recorded the worst results. Overall, our findings demonstrate that the unchanged water negatively affected the growth and physiological functions of Nile tilapia. Dietary incorporation of organic acids did not protect the fish from these hazards except the LA (1%). The latter can reduce nitrogenous compounds, enhance immune response, and alleviate these alterations for the sustainable aquaculture industry. [ABSTRACT FROM AUTHOR]

The current trial was designed to evaluate the positive impacts of different feed additives singly or in combination on the growth performance, nutritional parameters, intestinal histology, and gene expression of some growth and fat metabolism-related genes in the liver tissue of Nile tilapia. The experimented fish were allocated into eight groups in a glass aquarium (10 fish/aquarium in triplicate) with Pediococcus acidilactici, nanozeolites, and/or medium-chain fatty acid additives. The studied treatments were control (T0), nanozeolite (T1), Pediococcus (T2), medium-chain fatty acid (T3), nanozeolite + Pediococcus (T4), nanozeolite + medium-chain fatty acid (T5), Pediococcus + medium-chain fatty acid (T6), and nanozeolite + Pediococcus + medium-chain fatty acid (T7). The results of the growth and nutritional parameters (i.e., final body weight, total weight gain, feed intake, specific growth rate, feed conversion ratio, and protein efficiency ratio) of tilapia-fed diets supplemented with Pediococcus, nanozeolites, and medium-chain fatty acids improved, but the combination of these additives was significantly more effective. Moreover, expression of growth hormone receptor 1 gene was upregulated (P ≤ 0.05) in T7 fish when compared with T0, other groups showing intermediate values. Expression of insulin-like growth factor-1 was upregulated (P ≤ 0.05) in T5, T6, and T7 fish when compared with the other groups. The expression of the fatty acid-binding protein was higher in T6 and T7 fish (P ≤ 0.05) when compared with T0, T1, and T3 fish. In conclusion, combined additives had significant effects on improving growth and regulating growth-related genes. [ABSTRACT FROM AUTHOR]

Ectoparasites Dactylogyrus spp. mainly infest fish gills and severely damage the host's gill tissues. Correspondingly, the explanation of the interaction of fish with Dactylogyrus spp. infection is still insufficient. The present study describes the changes in hemato-biochemical, immune, antioxidant, genotoxic, and pathological indices response of Nile tilapia (Oreochromis niloticus) severely (n > 50), mildly infected (n = 1–50), and uninfected with Dactylogyrus spp. Data showed the adverse effect of hemato-biochemical indices in infected fish compared to uninfected, notably in severely infected O. niloticus. Compared to uninfected fish, there is a significantly decreased serum lysozyme and complement C3 and increased IgM and phagocytic activity along with significant upregulation of (COX-2), (IL-1β), (TNF-α), and (IL-10) genes in infected fish partially, in severely infected fish. Concisely, indices of antioxidants in the liver and gills marked an increased level of MDA in the infected fish compared to the uninfected fish. Conversely, levels of SOD, CAT, and GSH were decreased significantly with damaged DNA in the gills and liver of infected groups, particularly in severely infected (P < 0.05). Histopathologically investigating livers and gills in infected Nile tilapia indicated damaging and degenerative alterations, particularly with severe infection. Findings showed that Dactylogyrus spp.–infected Nile tilapia were effective in improving our knowledge of fish-pathogen interactions, which may be essential for fish defense against parasite infection. [ABSTRACT FROM AUTHOR]

Hexaflumuron (HEX) insecticide is widely used in agriculture practices to fight crop insects. The toxicological effect of HEX on Nile tilapia (Oreochromis niloticus) was investigated in this study. Two hundred and forty fish (35.50 ± 1.45 g) were divided into six groups in four replicates (40 fish/group; 10 fish/replicate) and were exposed to six distinct HEX concentrations (0, 2, 4, 6, 8, and 10 mg L−1) for 96-h. The 96-h lethal concentration 50 (96-h LC50) of HEX was calculated to be 7.19 mg L−1. The fish exhibited reduced surface and middle swimming, aggressiveness, and tail-spreading behaviors with increasing bottom swimming and resting patterns after HEX exposure. HEX exposure resulted in body bleeding and fin rot. The erythrogram (red blood cell count, hemoglobin, and packed cell volume %) was significantly reduced with increased mean corpuscular volume by HEX exposure. HEX exposure decreased the white blood cells (WBCs) and differential WBC counts. Acute HEX exposure raised 8-hydroxy-2-deoxyguanosine level while lowering brain acetylcholine esterase activity. HEX exposure caused hepato-renal dysfunction and increased stress-related parameters (glucose and cortisol). Exposure to HEX reduced the immune responses (lysozyme, nitric oxide, immunoglobulin M, and complement 3). A substantial decrease in the antioxidant variables (reduced glutathione content and catalase) with increasing the malondialdehyde was noted by HEX exposure. Moreover, histopathological changes resulted from HEX exposure in the gills, liver, kidney, and spleen. These results indicate that HEX exposure induced behavioral changes, hepato-renal dysfunction, and immune-antioxidant disruption, indicating a possible physiological disruption in O. niloticus. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the impact of administering the antibiotic florfenicol (FFC) through dietary means on Oreochromis niloticus. The experiment involved exposing the fish to FFC at doses 0–10 times the therapeutic dose of 15 mg/kg biomass per day for 10 consecutive days. The group receiving the therapeutic dose showed 100% survival on the 10th day of dosing. Histological analysis revealed dose‐dependent changes in the spleen, including an increase in sinusoidal space, splenic necrosis, white pulp proliferation, splenitis, and red pulp hemorrhages. Additionally, there was an exponential rise in leukocyte counts accompanied by a significant decrease in erythrocyte counts, indicating the development of anemia due to FFC. The observed splenic histological damage, along with increased erythrophagia, erythro‐membrane breakage, and poikilocytosis, highlighted the splenotoxic and hemotoxic effects of FFC at higher doses. Importantly, these toxic effects showed considerable reduction upon discontinuation of FFC dosing. The study emphasized the need to consider FFC‐induced splenotoxic and hemotoxic outcomes in O. niloticus during its application in aquaculture. [ABSTRACT FROM AUTHOR]

Simple Summary: Microalgae such as Spirulina platensis and essential oils derived from Citrus limon have potential growth-promoting, antimicrobial, antioxidant, and immunostimulant effects for several fish species. This manuscript spotlights Spirulina platensis and Citrus limon essential oil and their roles in improving the performance and health of Nile tilapia. Our results indicate that Spirulina platensis and/or lemon essential oil can be used as natural feed additives during aquafeed formulation to improve fish welfare through nutritional management. The dietary presence of feed additives is crucial for boosting fish growth and immunity. Accordingly, this feeding trial aimed to investigate the effects of the separate and concurrent dietary supplementation of Spirulina platensis (SP) and bitter lemon (Citrus limon) peel essential oil (LEO) on the growth, immunity, antioxidant capacity, and intestinal health of Nile tilapia (Oreochromis niloticus). Four groups of male Nile tilapia were employed. The first group (control) was given the basal diet, while the second and third groups received the basal diet supplemented with LEO extract (1%) and SP (1 g/kg diet), respectively. The fourth group received the basal diet supplemented with a mix of LEO (1%) and SP at 1 g/kg. After two months of feeding, using LEO or/and SP improved the overall growth and immunological parameters, with their combination yielding the best outcomes. The supplementation of LEO or/and SP improved the Nile tilapia's growth metrics and transcriptomic levels of growth-regulating genes such as (oligo-peptide transporter 1 (Pep1), growth hormone receptors 1 (GHR1), and insulin-like growth factor (IGF1). The improved growth performance was linked to significant increases in the expression levels of mucin and fat metabolism-related genes. Moreover, fish supplemented with LEO, SP, or their combination showed enhanced non-specific immunological measures, including phagocytic and lysozyme activities and the mRNA copies of its regulating genes. Additionally, remarkable increases in the antioxidant enzyme activities and the mRNA levels of their related genes were detected. The complement (C3) gene's transcriptomic level was also significantly increased. Furthermore, the dietary supplementation of LEO, SP, or their combination improved the histological structures of the spleen, hepatopancreas, and intestine. The enhanced effects of LEO, SP, or their combination on fish immunity and growth are suggested to be due to their contents of bioactive compounds with anti-inflammatory, antioxidant, and antimicrobial properties. Thus, using the LOE and SP blends as feed additives is recommended for better growth and immunity of Nile tilapia. [ABSTRACT FROM AUTHOR]

Bagega community is an artisanal mining community with a history of Pb poisoning. The community is served by a small lake as an important source of water for cattle watering, irrigation, washing, and fishing among other uses. The concentration of Cd, Cr, and Pb in soil and plants at the bank, surface water, sediment, and fish of the lake were analysed using Agilent 4210 MP-AES machine after microwave digestion using the Advanced Microwave Digestion System model (Ethos easy). The concentrations of Pb and Cr in water from Bagega Lake were found to be above the WHO acceptable limits. This presents a health risk to humans and other animals that utilize directly or indirectly utilize the water in the lake. Catfish (Clarias anguillaris) and Tilapia (Oreochromis niloticus) had higher Pb and Cr concentrations in the gills than in the liver and h muscle (flesh). The concentrations of Cr, Cd and Pb of soils in the bank and sediment of Bagega Lake were below the WHO acceptable limits. A total of thirteen (13) plant species belonging to seven (7) families were identified to be dominant around the Bagega Lake during the time of study and they all show the potential of bioaccumulation of Cr and Pb based on their BCF. [ABSTRACT FROM AUTHOR]