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Feed-based bivalent vaccine (FBBV) containing killed whole organism (KWO) of Streptococcus agalactiae and Aeromonas hydrophila with 10% palm oil was previously proved to improve red hybrid tilapia’s (Oreochromis sp.) immunity against streptococcosis and Aeromonas infections. This study characterized the FBBV’s stability following the preparatory process and storage. The FBBV was prepared, and the KWO’s stability was determined microscopically and molecularly. The efficacy of FBBV stored at room temperature (25 ± 2 °C) for 0, 30 and 60 days was investigated in red hybrid tilapia. The results indicated the addition of palm oil was not affecting the KWO’s structure and helping in the FBBV’s pelletization. In 1 g of FBBV contained 1.5 × 109 CFU/g of S. agalactiae and 4.9 × 109 CFU/g of A. hydrophila, respectively, even after 60 days of storage at room temperature. The KWO’s structure in FBBV was not affected following in vitro acidic tolerance analysis, as noted from light and electron microscopies. The FBBV’s carbohydrate, energy, moisture, total protein and total ash contents remained stable at 95% after 60 days of storage at room temperature, while the KWO’s concentration was slightly reduced to 83.3% for S. agalactiae (1.25 × 109 CFU/g) and 80.6% for A. hydrophila (3.85 × 109 CFU/g), respectively. Fish vaccinated with FBBV that was stored for 0, 30 and 60 days did not show any significant differences (p ≥ 0.05) in the relative percent survival when challenged with pathogenic Streptococcus spp. and Aeromonas spp. These findings suggested that the FBBV is a stable vaccine, which underscores its potential application as aquatic vaccines in aquaculture. [ABSTRACT FROM AUTHOR]

Tilapia is a model fish species used as a pollution biomonitor due to its tolerance and availability in many contaminated sites. Blue tilapia Oreochromis aureus specimens (n = 320) were collected in eleven dams influenced by mining in the SE Gulf of California region (dams 1, 2 and, 3 comprise 55 mining sites; dam 4 comprises 8; dams 6, 8, 10, and 11, ≤ 6; and dams 5, 7, and 9 include 19, 20, and 16 mining sites, respectively). Cadmium, Cu, Pb, and Zn concentrations were analyzed in the muscle, liver, gills, and guts to identify metal pollution and evaluate risks and seasonal changes. The distinct tissues exhibited different metal accumulation capacities, therefore allowed develop a diagnosis comparative between the eleven dams. In general, metal concentrations were higher in dams 1, 2, 5, and 9, which are associated with more mining sites in their sub-basins. The four metals exhibited the highest levels in the tilapia liver in dams 1 and 2, which can be related to the present and past mining activity in the lower watershed (55 sites) and the geothermal activity in these dams. In general, Zn exhibited the highest level in the tilapia livers from dams 1, 2, 3, 4, 5, and 10 compared to the maximum mean (220 µg/g) concentrations previously recorded. The non-carcinogenic risks indicated that the Pb risk was enhanced when the intake was ≥ 231.5 g week−1 of tilapia muscle, indicating a potential risk of adverse health effects for the entire population. [ABSTRACT FROM AUTHOR]

The cold stress during overwintering is considered the bottleneck of red tilapia industry. In this study, the water temperature (WT) was reduced by 2 °C per day from 20 °C to 8 °C in the cold (C) group. Then transcriptome of brain(B), gill(G), liver(L) and skin(S) tissues and proteome of G, L and S tissues were performed in C and Normal (N) (WT: 20 °C) group. 24 transcriptomes were completed, and 168.8 Gb data were obtained, with more than 5.89 Gb clean data of each sample. A total of 30499 annotation results were obtained with 3199, 4697, 4393, and 3382 differentially expressed mRNAs in NB_vs_CB, NG_vs_CG, NL_vs_CL, NS_vs_CS. 18 DIA proteomes were performed, and 6341 proteins were obtained with 178, 500 and 166 differentially expressed proteins in NG_vs_CG, NL_vs_CL, NS_vs_CS. Our datasets can be reused for key genes and proteins identification, omics joint analysis and regulatory mechanism analysis of low temperature or cold stress in fish, which will help understanding the regulatory mechanism and facilitate the molecular selective breeding of cold-resistant varieties of fish. [ABSTRACT FROM AUTHOR]

Tilapia lake virus (TiLV) is a novel single-stranded RNA virus that is considered a threat to the universal tilapia industry. Recombinant technology proved to apply to different viruses and does not require handling live viruses. The present study developed a recombinant protein from segment 4 of TiLV with the aim of developing an immunological detection method for the virus. For this purpose, the complete coding sequence of segment 4 of the virus was optimized, amplified, and cloned in pET-28a(+), a prokaryotic expression vector, and the TiLV segment 4 construct (pET-seg4) was developed. The recombinant protein was expressed in BL21-competent Escherichia coli by isopropyl-β-D-thiogalactopyranoside (IPTG) induction. The successful expression of the recombinant protein was confirmed by SDS-PAGE. The polyclonal antibody (PAb) raised against the recombinant protein was used for the indirect enzyme-linked immunosorbent assay (ELISA) development to detect TiLV in the pooled kidney and mucus samples. The coating concentrations for the recombinant protein and the TiLV-positive samples were standardized as 3.125 µg and 6.25 µg, respectively, and the optimum polyclonal antibody dilution was found as 1:800. The diagnostic sensitivity and diagnostic specificity of the assay were 82.35% and 100%, respectively. The recombinant protein developed in this study provided a better understanding of raising a codon-optimized protein and its use in developing an indirect ELISA test for TiLV, which can also be used as a recombinant vaccine for immunizing tilapia. [ABSTRACT FROM AUTHOR]

Two tilapia species, Oreochromis aureus and Oreochromis niloticus, were introduced into Morocco in 2004 for fish farming. O. niloticus was subsequently introduced into the wild in several watersheds. During a fish survey at six locations, we observed other specimens of tilapia that appear to be more related to O. aureus. Partial sequences of COI and S7 genes and geometric morphometrics were used to assess the specific status of all the specimens. Out of 1691 specimens sampled, 159 COI and 153 S7 partial sequences were obtained and confirmed the presence of both species. O. aureus was present in part of Rabat-Salé-Kenitra region (the Nador Channel (NC), Al Kansra dam (AK) and Oued Sebou (OS)) while O. niloticus was found in the fish farm (AS), in the province of Rabat (Sidi Mohamed Ben Abdellah dam (BA)) and the region of Casablanca-Settat (Al Massira dam (AM)). A few hybrids were identified at AS and OS. Body shapes and sizes were assessed using geometric morphometrics with 18 landmarks and were found to differ significantly between O. aureus and O. niloticus. Both species exhibited significantly different allometric changes during their growth, but kept their morphological signature independently of their specific allometric changes during growth. Specimens from riverine environments (OS, NC) had a similar shape with an elongated body with a large head and eye, while individuals found in lacustrine environments (AK, AM and BM) had a larger body depth, small head and eye. Morphometrics also suggested that hybrids or sympatry could occur to a small extent in AS, OS and NC. [ABSTRACT FROM AUTHOR]

The present study aimed to determine the anaesthetic effectiveness, safety, and applicable concentrations of coriander (Coriandrum sativum) essential oils (CEO) for three-spotted tilapia (Oreochromis andersonii). For this purpose, CEO concentrations of 400, 500, and 600 µL/L were tested at two temperatures, 20.90 ± 1.19 °C and 30.60 ± 0.92 °C, on three different sizes (small, medium, and large) of the fish in duplicate glass aquaria with 200 mg/L of tricaine methanesulfonate (MS-222) served as the control. The sedative efficacy during simulated transportation experiments was also carried out. The results demonstrated that the induction and recovery time in O. andersonii anaesthetised with CEO were significantly influenced by concentration, water temperature, and fish size (P < 0.05). A concentration of 600 µL/L of CEO was found to be highly effective in inducing deep anesthesia and promoting rapid recovery in small and medium-sized fish at both water temperatures (20 and 30 °C). Based on this study, 100 µL/L of CEO is recommended for short-term transportation lasting up to 4 h, while 50 µL/L is advised for longer-distance transport. Although coriander essential oil shows anaesthetic effectiveness in three-spotted tilapia, further research is needed to fully understand the efficacy and safety of CEO across different fish species. [ABSTRACT FROM AUTHOR]

Microplastic (MP) ingestion through fish consumption is a concern for human exposure. While the presence of plastic particles in fish tissues has been documented worldwide, information on microplastic concentrations in edible tissues, especially those smaller than 10 µm, remains scarce. Spectrometric techniques provide a complementary analytical tool to measure MP mass for human exposure studies without intrinsic size limitations; however, their application to fish analysis is limited. In this study, we utilized pyrolysis gas chromatography–mass spectrometry (Py-GC–MS) for the identification and quantification of MPs in fish muscle tissues. Two sample preparation methods, pressurized liquid extraction, and chemical digestion, were tested for compatibility with Py-GC–MS analysis. An analytical method using chemical digestion was validated for analyzing particles ≥ 0.7 µm for 4 polymer types: polypropylene, polyethylene, polystyrene, and polymethyl methacrylate. The developed method was applied to 24 adult Nile tilapia (Oreochromis niloticus) samples from a recirculating aquaculture system. MPs were detected in 42% of the samples, with an average concentration of 0.14 ± 0.32 µg/g, while high variations within subsamples were observed. Our findings reveal trace amounts of MPs in edible fish tissues from aquaculture, highlighting the potential risk of microplastic ingestion through fish consumption. This underscores the need for further risk assessments to evaluate the impact on human health and to develop appropriate mitigation measures. [ABSTRACT FROM AUTHOR]

Impact of opportunistic bacterial pathogens and their antimicrobial resistance continues to increase in aquaculture, posing significant public health concerns. The present study aimed to investigate the incidence of mortality in cultured Nile tilapia, O. niloticus in Andhra Pradesh, India. Diseased samples exhibiting exophthalmia, swollen abdomen, hemorrhages and pale gills were collected to isolate pathogenic bacteria. The bacteria were characterized using cultural, biochemical characteristics and 16 S rRNA gene sequence. The isolate had 99.66% homology with Micrococcus luteus (GenBank accession no. PP659810). The cumulative mortality LD50 was calculated as 1.39 × 105 CFU per fish. Histopathological alterations revealed hyperplasia and fusion of gill lamellae, enlarged hepatocytes, degenerative renal tubules, fibrous lesions, ellipsoidal compression of white pulp, degeneration of splenic tissue, and melano-macrophage centres. Antibiogram studies revealed that M. luteus showed varying degrees of resistance to different antibiotics, with a multiple antibiotic resistance index of 0.62 ± 0.3. Mortality rate in cultured farm and experimental infection is 30% and 70%, respectively. These findings highlight that M. luteus can be considered as one of the potential bacterial pathogens in Nile tilapia. Our findings highlight that Good Aquaculture Practices (GAP), biosecurity, disease surveillance, and the One Health Approach are essential for tackling AMR- and disease-related issues. This report forms the first record of emergence of M. luteus infection in cultured Nile tilapia, O. niloticus in India. [ABSTRACT FROM AUTHOR]

In the aquaculture industry, tilapia farming stands out as one of the most lucrative and rapidly expanding trades. The farming of tilapia has witnessed significant growth due to its high protein content, large size, fast growth, and culinary appeal. However, as aquaculture becomes more intensive, tilapia are increasingly susceptible to emerging infections. Epidemics of tilapia lake virus (TiLV) disease during the summer months have been observed to cause significant mortality in tilapia across various life stages. Seaweed-derived bioactive substances have been extensively studied for their broad antiviral properties. These compounds can enhance the host's immune responses or directly target and inhibit virus replication before it infects host cells. Highlighting the serious concerns of emerging disease in farmed tilapia, and possibility of exploring novel compounds for disease remediation, the present review explores seaweeds as a valuable source of antiviral agents for the development of innovative vaccines and medications against TiLV. The review highlights future research directions to expedite the development of new disease treatments in tilapia farming. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of interactions between β-glucan-enriched complex and vitamin premix on the zootechnical performance and histological and histomorphological parameters of the gastrointestinal tract of juvenile Nile tilapia (Oreochromis niloticus). The diets were supplemented with a manufacturer-indicated dosage of vitamin Premix at 1.5 kg ton feed−1 (Vit1.5 treatment) and with a high level of vitamin Premix at 2.0 kg ton feed−1 (Vit2.0 treatment), with or without the β-glucan-enriched complex added at a concentration of 5.0 kg ton feed−1. Thus, the fish were subjected to four treatments: Vit1.5 (control group), which consisted of individuals supplemented with the indicated level of vitamin Premix; Vit1.5 + β-glucan group, which consisted of individuals supplemented with Vit1.5 + β-glucan-enriched complex; Vit2.0 group, which consisted of individuals supplemented with a high level of vitamin; and Vit2.0 + β-glucan group, which consisted of individuals supplemented with Vit2.0 + β-glucan-enriched complex. Twenty-eight experimental units with 40 fish each were used, totaling 1120 juveniles (2.5 ± 0.10 g and 4.9 ± 0.10 cm) fed for 30 days, and the data were collected at the end of the experimental period. There was an improvement in the final weight, final weight gain, and specific growth rate, as well as hepatic sinusoidal congestion, a mononuclear infiltrate, a decrease in microsteatosis, pyknosis nuclei, and melanomacrophage centers, a mononuclear infiltrate, as well as congestion in the spleen and an increase in the number of goblet cells and villi in the intestine. The interaction between β-glucans and vitamin premix in artificial diets for tilapia has been shown to improve zootechnical parameters, albeit slightly, and has led to the development of tissue adaptations in the gastrointestinal tract to improve nutrient absorption. However, pathological conditions were observed in the liver and spleen, and we suggest future research with longer feeding times and subsequent exogenous challenges to confirm these alterations. [ABSTRACT FROM AUTHOR]

Protein degradation is a common occurrence in tilapia during the refrigeration process, leading to the generation of unpleasant odor and impacting overall flavor and quality. This study characterized the protein degradation of tilapia during cold storage and utilized amino acids metabolomics analysis to identify metabolic pathways and differential metabolites associated with odor formation and changes. The protein degradation of tilapia during cold storage was characterized through analysis of trichloroacetic acid (TCA) soluble peptides, protein concentration, electrophoresis patterns, protein secondary and tertiary structures, as well as microscopic structures. The characterization of these indicators revealed an obvious protein degradation and structural disruption of tilapia during cold storage. Changes in the types and contents of free amino acids (FAAs) were discussed. Protein degradation produced a large number of FAAs, with Lys contributing the most to flavor changes. By employing amino acids metabolomics analysis, primary and secondary differential metabolites were selected, along with differential metabolic pathways based on amino acids metabolism. And the related amino acid metabolic network was constructed. This study contributes to revealing the impact of amino acids metabolism on odor formation and changes, providing further insights for the research and regulation of odor. [ABSTRACT FROM AUTHOR]

This research examined how three phytobiotics impact the growth, utilization of feed, immune response, and resistance of Nile tilapia (Oreochromis niloticus) to disease. A total of 180 fish, with an average initial weight of 31.2 g (number = 15 per 150-L tank), were randomly divided into four groups, with each group replicated three times. Fish were fed isoenergetic (15.7 kJ g−1 gross energy) or isonitrogenous (262 g/kg−1 crude protein) control diets supplemented with 1% Calopogonium mucunoides, Ocimum gratissimum, or Tridax procumbens leaf meals, and the feeding trial lasted 10 weeks. The growth performance, feed utilization, and innate immunity of the fish were measured. Ten fish from each replicate were intraperitoneally injected with Streptococcus agalactiae, and mortality was recorded for 18 days. The O. niloticus fed phytobiotic-enriched diets exhibited significantly greater weight gain (68.6 ± 3.7; 70.3 ± 1.6; 71.6 ± 2.9) and specific growth rates (1.70 ± 0.05; 1.71 ± 0.01; 1.73 ± 0.06) than did those in the control group (55.3 ± 1.1; 1.50 ± 0.05). Additionally, phytobiotic supplementation in Nile tilapia diets positively impacted feed conversion efficiency, protein efficiency ratio, feed conversion ratio, hematocrit, hemoglobin, red blood cells, lymphocyte count, serum protein profile, glucose level, kidney-liver function, and bactericidal and lysozyme activities. Following the challenge with S. agalactiae, the survival rates were significantly greater (p < 0.05) in the fish fed a diet supplemented with O. gratissimum (70%), T. procumbens (63.3%), or C. mucunoides (53.3%) than in those in the control group (26.3%). The abovementioned phytobiotics incorporated into Nile tilapia feed can boost production and enhance growth performance, feed efficiency, immunity, and resistance to disease. [ABSTRACT FROM AUTHOR]

Vibrio cholerae is the causative agent of cholera, an acute diarrheal disease that spreads locally and globally in epidemics and pandemics. Although it was discovered that fish harbor V. cholerae strains in their intestines, most investigations revealed non-toxic V. cholerae serogroups in fish. Due to the rarity of toxigenic V. cholerae serogroups, it is difficult to cultivate these strains from environmental samples. Hence, here we aimed to uncover evidence of the occurrence of toxigenic V. cholerae in the intestines and spleens of various fish species. By using molecular detection tools, we show that V. cholerae O1 and strains positive for the cholera toxin inhabit both healthy and diseased fish intestines and spleens, suggesting that fish may serve as intermediate vectors of toxigenic V. cholerae. No significant differences were found between the abundance of toxigenic V. cholerae (either O1 or cholera toxin positive strains) in the healthy and the diseased fish intestines or spleens. In conclusion, a variety of fish species may serve as potential vectors and reservoirs of toxigenic V. cholerae as they form a link between the other reservoirs of V. cholerae (chironomids, copepods, and waterbirds). Similarly, they may aid in the spread of this bacterium between water bodies. [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]

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]

Aquaculture is expanding globally, but intensive rearing conditions can cause diseases due to microbial infections leading to financial losses. Probiotics can be used in tilapia farming instead of antibiotics to improve fish health, growth and are environmentally friendly. We provide a synthesis (meta-analysis) of empirical findings to increase statistical power and produce strong evidence for well-informed decision-making with respect to the use of pro, pre, and synbiotics in tilapia culture. In this meta-analysis, we investigated the effects of dietary probiotics on the immune response modulation and resistance of tilapia against common diseases. A systematic search was performed, and the data from 67 studies were included for review and meta-analysis. Pre-challenge, dietary probiotics led to a significant increase (p < 0.001) in the weight gain and specific growth rate, a significant decrease (p < 0.001) in the feed conversion ratio, but a non-significant increase in survival (p > 0.05). However, probiotics significantly (p < 0.001) enhanced innate immunity based on serum lysozyme, phagocytotic activity, and phagocytotic index, while disease resistance (survival) of tilapia against pathogenic challenge was also significantly (p < 0.001) enhanced. From this study, three categories of probiotics were identified such as single-strain probiotics (SSP), multi-strain probiotics (MSP), and symbiotics (S). The use of synbiotics (probiotics + prebiotics) showed the best effect compared to other probiotic categories, however, more research is needed to ascertain the superiority of synbiotics over other categories. This study concluded that probiotics generally contribute significantly to the growth, immunity, and disease resistance of tilapia. [ABSTRACT FROM AUTHOR]

The myxosporean infection and its phylogenetic analysis were investigated in tilapia (Oreochromisniloticus) with average weight (70 ± 5 g) and crayfish (Procambarusclarkii) with average weight (20 ± 6 g). The prevalence of myxosporean infection was 100% for tilapia gills and internal organs without any specific clinical signs. Gross examination of affected tilapia showed enlargement of posterior kidney with macroscopic white nodules in kidneys and gills while crayfish gills showed black spots. Microscopic examination of the fresh preparation of kidneys of tilapia showed spores of Myxosporea. Moreover, the hepatopancreas fresh samples of crayfish demonstrated myxosporean spores. The gene sequencing of 18S gene from tilapia kidneys followed by phylogenetic analysis revealed that the isolated parasite had the highest sequence similarity to Myxobolus sp. ram SR-2018 [MK203074.1] giving 89.77% identity and was named Myxobolus sp. Egy1. In crayfish, histopathological examination showed the developmental stages of Myxosporea in the lumen and stroma of gill lamellae with degeneration of lining epithelium. In addition, different developmental stages of Myxosporea were scattered in the lining epithelium and lumen of hepatopancreas with vacuolation and multifocal deformation. In tilapia, histopathology revealed severe degenerative changes in the gill lamellae and renal tubules with presence of different developmental stages of Myxosporea. These findings support the high prevalence of myxosporean infection, particularly Myxobolus, in tilapia that induced histopathological damage in gills, and internal organs. Interestingly, we detected myxosporean spores in gills and hepatopancreas of crayfish which is considered a first report that needs further phylogenetic and epidemiological investigations. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effects of substituting soybean meal with fermented rapeseed meal (FRM) on growth, antioxidant capacity, and liver and intestinal health of the genetically improved farmed tilapia (GIFT, Oreochromis niloticus). A total of 450 tilapia (7.22 ± 0.15 g) were fed with five experimental diets, including a basal diet containing 40% soybean meal (CP0), which was subsequently replaced by 25% (CP25), 50% (CP50), 75% (CP75), and 100% (CP100) FRM in a recirculated aquiculture system for 9 weeks (30 fish per tank in triplicates). The results showed that the weight gain, specific growth rate, feed intake, feed efficiency, hepatosomatic index, and viscerosomatic index of fish in both CP75 and CP100 groups were significantly lower than those in CP0 group (P < 0.05). The fish in CP100 group had the lower content of muscle crude protein while the higher level of muscle crude lipid (P < 0.05). Activities of serum aspartate aminotransferase, alanine aminotransferase along with total triglyceride in CP100 group were significantly higher than those in CP0 group (P < 0.05). There were no significant differences in the contents of liver protease, amylase, and lipase among five groups (P > 0.05). The activities of liver total antioxidant capacity and superoxide dismutase exhibited the increased tendency with the increase of FRM replacement levels from 25 to 50% (P < 0.05), while then significantly decreased from 75 to 100% (P < 0.05). Histological morphology indicated that the fish in between CP75 and CP100 groups had poor liver and intestine health. Intestinal microbial diversity analysis showed that the relative abundance of Cetobacterium and Alcaligenaceae in both CP75 and CP100 groups were lower than that in other three groups. In conclusion, the maximum replacement level of soybean meal with FRM in the diet was determined to be 50% without compromising the growth performance, antioxidant status, and liver and intestinal health of tilapia under the current experimental conditions. The observed decrease in food intake and subsequent retarded growth performance in the CP75 and CP100 groups can be attributed directly to a reduction in feed palatability caused by FRM. [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]

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 FROM AUTHOR]

The aim of this study was to investigate microplastic (MP) exposure by Nile tilapia (Oreochromis niloticus) in laboratory conditions. A total of 150 tilapia fishes were equally distributed randomly in 15 different glass tanks with five experimental conditions. Observed results depicted that the presence of MPs in different organs was mainly accumulated from the fish feed rather than externally added MPs in the culture tanks. It was also revealed that the gastrointestinal tract (GIT) was found to be the most susceptible to MPs accumulation followed by gills and muscles in order. However, muscle contained the least size of MPs followed by GITs and gills. A statistical test showed significant correlations among the average length and weight of fish with MP exposure. A filamentous shape was found to be dominant in both GITs and gills while fragment shape was dominant in muscles. FTIR results revealed a total of 12 different polymers in the fish of which two polymers (polyvinyl alcohol and ethylene vinyl acetate) were not detected in the feed-only tanks. Polypropylene (PP) and polyethylene terephthalate (PET) were found to be dominant polymers in all the experimental GIT, gills, and muscle organs. FESEM results indicated the presence of different textures including cracks, edges, flakes, scratches, grooves, and adhering particles. EDX results exhibited the presence of Na, Si, K, Ni, Cu, Zn, As, and Cd in the analyzed samples that may pose additional health risks. Thus, this study could act as baseline data for laboratory-based studies of aquaculture species in future research. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the bioflocculant chitosan and its nano-conjugated form in biofloc production and to evaluate the growth performance of genetically improved farmed tilapia (GIFT) in an insitu biofloc system. A completely randomised design (CRD) was used to evaluate the growth performance of GIFT in insitu biofloc over a 75-day period. The trial was conducted with biofloc control (T1), 30 ppm chitosan (T2) and 30 ppm nano-chitosan (T3) in triplicate. The water quality parameters were maintained in the optimum range for biofloc production. The highest value for flocculation activity, total suspended solids, total dissolved solids and total solids other than floc volume was observed in T3 followed by T2 and T1. The result of this study showed that there was a significant difference (p < 0.05) between treatments in terms of specific growth rate (SGR), weight gain (%WG), feed conversion ratio (FCR), feed efficiency ratio (FER) and daily increment (DI). Good growth performance of fish was observed in biofloc produced with nano-chitosan in terms of average body weight (g) (24.74 ± 2.58), SGR (%/day) (3.56 ± 0.094), PWG (%) (1546.27 ± 143.42), lowest FCR (1.421 ± 0.029), FER (0.62 ± 0.011), PER (1.68 ± 0.03) and DI (g day−1) (0.21 ± 0.014). The highest levels of amylase, lipase and protease activity and increased activity of antioxidant enzymes (SOD and CAT) were found in the T3 treatment compared to T2 and T1 treatments. This study demonstrated that biofloc developed with 30 ppm nano-chitosan could shorten the production time of biofloc, maintain the water quality of the biofloc system and improve the growth of GIFT tilapia reared in an insitu biofloc system with inland saline groundwater. [ABSTRACT FROM AUTHOR]

Pharmaceutical incompatibility of clove oil due to its immiscibility in water may affect the safety, efficacy, appearance, and stability of the drug during immersion anesthesia. Though there are reports of using ethanol to enhance the anesthetic efficacy of clove oil, there are no reports of quantitative calculations of anesthetic efficacy and stages of anesthesia for this combination. To overcome this issue, a study was designed to enhance the miscibility of clove oil in water by incorporating ethanol as an interphase. Two trials were conducted using clove oil at concentrations of 50 and 100 mg/L, respectively, dissolved in ethanol at a 1:10 ratio. These trials were performed on tilapia fishes (Oreochromis mossambicus) to evaluate the time required for anesthesia induction, duration (maintenance time), and recovery from anesthesia. The results of the study showed an induction time of 1 min for the 100 mg/L concentration and 10 min for the 50 mg/L concentration. The duration of action was observed to be 12 min for the 100 mg/L concentration and 31 min for the 50 mg/L concentration, respectively. The recovery times were 10 min and 3 min for the 100 mg/L and 50 mg/L doses, respectively. Changes associated with various stages and planes for surgical anesthesia were also documented in this study. This study concludes that the mixture of clove oil and ethanol serves as a more effective general anesthetic for fish compared to conventional clove oil immersion anesthesia. [ABSTRACT FROM AUTHOR]

Survival analysis has proven to be a robust tool for studies in humans, and recently, it has been adopted in studies with animals, but very little in fish. The production of uniform fingerlings has been one challenge of aquaculture, influenced by the use of the efficient breeders. We aimed to present, for the first time in aquaculture, a survival analysis as a tool for decision-making by using the relationship between the main morphometric traits and the spawning time of Nile tilapia females up to 28 days after mating in an intensive system. We used 78 females and 26 males from which ten traits were evaluated. A check was made for the presence of eggs in the female mouth (spawning) every seven days until the final twenty-eight days. Confirmation of eggs was defined as uncensored data (C = 1) and absence of eggs as censored (C = 0). The Cox proportional hazards ratio and Kaplan–Meier models were adjusted to analyze the data. Females with a standard length of 19.19 cm (small group) and males with a weight of 259.14 g (small group) reproduced early, being more adapted to 1000 L tanks in a recirculation system. Less heavy egg masses were also related to early spawning. Therefore, the traits, standard length of the female, egg mass weight, and male weight, affected the presence of eggs up to 28 days and should be used as selection criteria for early breeders. Besides, the survival analysis was accurate as a tool for tilapia breeding management in an intensive system. [ABSTRACT FROM AUTHOR]

Lakes are among the main sources of protein and livelihood to huge communities of rural people, and some of them house endemic fish species. The livelihood of about 200,000 rural people depends on Lake Manyara resources which also houses a population of the endemic and endangered fish, the Manyara Tilapia (Oreochromis amphimelas). Despite this importance, fishery in the lake is nearly under open access and it is not known how this has affected fish stocks. The lake is also under strong influence from overgrazing and poor farming practices in the highlands and adjacent areas which are polluting the lake. However, it is also not known how this has affected the growth and survival of fish in the lake. We assessed the impact of artisanal fishing and anthropogenic pollution on the stock of Manyara Tilapia and Nile Tilapia in Lake Manyara. We found that fish stocks in the lake are under heavy fishing pressure. Nearly all harvested Nile Tilapia were immature, and the majority of Manyara Tilapia were first time spawners caught at the length of their first maturity. This prevented the fishes from spawning at least once in their lifetime. Anthropogenic pollution has also hypereutrophied the lake and degraded the ecological quality for growth of Tilapia fish. Therefore, urgent site-specific mitigation measures and conservation actions are required to safeguard community livelihood and continued existence of the endangered Manyara Tilapia. [ABSTRACT FROM AUTHOR]

Endogenous opioids are found in the central nervous system and multiple peripheral organs and affect the hypothalamus–pituitary–gonad axis at several levels in vertebrates. However, the influence of these opioid peptides on fish spermatogenesis is poorly studied. This investigation examined the impact of the opioid peptide dynorphin-A (DYN) on the pituitary–testicular axis in the tilapia Oreochromis mossambicus. Intraperitoneal injections of 5 µg DYN/day/fish for 21 days did not affect the early developmental stages of germ cells, but caused a significant decrease in the numbers of secondary spermatocytes and early and late spermatids compared with the controls. Although the mean area of the lobule was significantly decreased, there was a significant increase in the areas of the lumen and the interstitium in the DYN-treated group relative to controls. These results were concomitant with significantly lower serum levels of 11-ketotestosterone (11-KT) and luteinizing hormone (LH) in DYN-treated fish than in controls. However, the serum level of cortisol was significantly higher in the DYN-treated fish group. Overall, these results, for the first time, indicate that DYN interferes with spermatogenesis at the late stage of meiosis, leading to impairment in spermiogenesis, possibly mediated through the suppression of 11-KT secretion in the testis and LH release from the pituitary. This study also suggests that DYN may bring about this inhibitory effect via activation of the stress axis in teleosts. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of selenium nanoparticles on growth performance, survival rate, chemical composition, and bioaccumulation of selenium in the muscle of Nile tilapia (Oreochromis niloticus). Fish with an average weight of 33.1 ± 1.0 g were distributed in 12 fiberglass tanks and fed for 56 days with different levels of selenium nanoparticles, 0, 0.5, 1, and 2 mg/kg of diet, considered as control, T1, T2, and T3, respectively. Body weight increase (BWI), specific growth rate (SGR), and food conversion ratio (FCR) were significantly influenced by 2 mg/kg of selenium nanoparticles compared to the other treatments, in particular control and T1 with 0.5 mg/kg selenium (P < 0.05). The survival rate was also significantly affected in T2, especially compared to the control (P < 0.05). In addition, protein, ash, and moisture percentages of muscle showed statistically different levels in fish fed a diet containing 2 mg/kg of selenium nanoparticles compared to the control treatment (P < 0.05). The results of the selenium bioaccumulation in the muscle of trial diets showed a significant difference in selenium nanoparticle bioaccumulation among treatments, with the highest revealed in the 2 mg/kg nanoparticle group (P < 0.05). Overall, selenium nanoparticles significantly improved the growth performance, survival, and chemical composition (protein in particular) of Nile tilapia, especially in the T2 and T3 treatments. [ABSTRACT FROM AUTHOR]

This study provides comprehensive results on the growth, thyroid, liver, and gonadal condition, maturity, and sex ratio in red tilapia exposed to exogenous thyroxine and goitrogen. One-gram red tilapia fingerlings were reared in three groups: control, thyroxine (T4) (10 nM), and goitrogen (sodium perchlorate, 30 mg/L) for 30 days, followed by 30 days without treatment. After the first 30 days of treatment, liver enzymes and whole-body T4 and T3 were assessed. The gonadosomatic index (GSI), maturity stages and sex ratio were examined. Final body weight (FBW), weight gain (WG), specific growth rate (SGR), and survival rate were also measured. Results revealed insignificant differences among groups in FBW, WG, SGR, and GSI, but the hepatosomatic index (HSI) of the goitrogen group significantly increased. Exogenous thyroxine significantly increased whole-body T4. Liver enzymes were not affected. Thyroid follicles of the thyroxine-treated fish showed large thyroid follicles, whereas the goitrogen-treated fish showed degenerated and negligible thyroid follicles. Liver tissue of the thyroxine-treated fish group displayed a few fat vacuoles, while perchlorate-treated fish showed hydrophobic degenerated hepatocytes. At the end of 60 days, the thyroxine treatment significantly increased FBW, WG, SGR, female GSI, and male hepatosomatic index (HSI). Perchlorate and thyroxine exposure, respectively, skewed sex ratios toward males and females. Exogenous T4 enhanced the maturity stages of both females and males, while perchlorate exposure delayed their gonadal ripening. These results validated the significant role of T4 during early life of red tilapia as it could improve the growth and maturity, and affect its sex ratio, while T4 insufficiency could alter these factors. [ABSTRACT FROM AUTHOR]

Nile tilapia [Oreochromis niloticus (Linnaeus, 1758)] is a widespread invasive fish, now present in lakes, rivers, and reservoirs around the world, and its dominance has led to serious ecological problems in many freshwater systems. However, little is known about its effect on macrophyte-dominated lake ecosystems. We conducted a 10-week mesocosm experiment to test the impact of tilapia on phytoplankton and water quality in model ecosystems with submerged macrophytes [Vallisneria natans (Lour.) Hara] and the presence and absence of tilapia. Tilapia led to an increase in concentrations of total phosphorus, total nitrogen, total dissolved nitrogen, ammonia nitrogen, and total suspended solids and had negative impact on submerged macrophyte and light intensity, thus causing an overall deterioration in water quality. Tilapia increased the abundance of rotifers and changed the zooplankton community structure. Tilapia increased the total biomass of phytoplankton but the effect depended on the phytoplankton size, i.e., the overall proportion of micro-phytoplankton increased, while that of pico-phytoplankton decreased. Thus, tilapia also caused changes in the phytoplankton community structure. Our research shows that tilapia deteriorates water quality and modifies phytoplankton and zooplankton Communities of shallow lakes. [ABSTRACT FROM AUTHOR]

Fish communities of tropical lakes are commonly predicted by local environmental variables, including depth, temperature, oxygen concentration, and substrate composition. Increasingly, however, lacustrine fish communities are being impacted by invasive species. In the state of Quintana Roo, on the Caribbean versant of the Yucatan Peninsula in Mexico, inland aquaculture production has resulted in the widespread establishment of African tilapia (Oreochromis sp.). However, there are still limited quantitative data on their abundance relative to indigenous species, or their influence on native fish diversity. Here, we quantified the ichthyofauna of six lakes from this region, alongside physical and chemical environmental variables. Overall, we observed that greater dissolved oxygen concentration and shallower depths were associated with the highest fish biodiversity across lakes. Moreover, spatial comparisons additionally highlighted the importance of substrate heterogeneity and lake area as influential in determining native fish community structure. Notably, in all lakes, tilapia were relatively uncommon, comprising less than 3% of all fish captured, and their presence was not a significant predictor of indigenous fish biodiversity. Based on these results, we suggest that tilapia may have strong limitations on their population size, plausibly due to the presence of predatory native fish species, or scarce suitable ecological resources (food, breeding habitat). Conservation-focussed lake-wide management of native species via protection of core habitat characteristics may be key to promoting environmental resistance against negative effects of tilapia regional expansions. [ABSTRACT FROM AUTHOR]

Although the involvement of β-endorphin (β-ERP) in vertebrate reproduction has been suggested, its role in testicular activity is not clear in fish. We describe the influence of β-ERP on spermatogenesis in a cichlid fish in the present paper. In comparison to the control group, the administration of β-ERP (3 µg) caused a significant increase in the number of spermatogonia-A and spermatids. Following treatment with β-ERP (6 µg), a significant increase in the number of spermatogonia-A was observed, whereas the numbers of all the other germ cells, excluding spermatogonia-B, significantly decreased in comparison to those in the control group. In addition, treatment of fish with 6 µg β-ERP resulted in a significant reduction in the dimensions of the lumen and seminiferous lobules, the level of immunopositive androgen receptor (AR) expression in Sertoli cells, and the percentage of luteinizing hormone (LH) immunolabeled in the pituitary compared to those in the control group or the group treated with 3 µg β-ERP. In contrast, the intensity of AR immunoreactivity and the percentage of LH immunolabeling were substantially increased in fish treated with 3 µg β-ERP compared to those in the control group. These findings reveal for the first time that a low dose of β-ERP stimulates the recruitment of spermatogonia as well as spermateleosis, whereas a high concentration affects the recruitment of germ cells prior to meiotic division in tilapia. These results suggest that β-ERP exerts modulatory effects at the testicular and hypophysial levels through alterations in AR expression and LH secretory activity, respectively, in teleosts. [ABSTRACT FROM AUTHOR]

Background: Collagen extracted from fish body parts is a promising biological material. It has an important role in many pharmaceutical, medical applications and tissue engineering such as corneal regeneration and stromal replacement. The present work investigates a new trend to extract collagen from the fish cornea, as a prospected substituent of human corneal collagen by characterizing some biochemical and optical properties of the fish corneal collagen. Results: Examination of the corneal tissue of Nile tilapia; Oreochromis niloticus was conducted using electron microscopy, Fourier transform infrared (FTIR) spectroscopy, UV–visible spectrophotometry, optical properties, and thermal properties. The fish were divided into 10 groups each of which consisted of 5 fish. 2 groups of fish were examined for each technique. Results indicated that the corneal layers of O. niloticus are thin at the center and thicker at the periphery with the stroma consisting of a triple helical structure collagen type I. The fish cornea showed very weak transmission at the UV regions (190 nm) and maximum transmission at the visible regions. The values of transmission (T), reflected light (R) and scattered light (S) were 2.685 mw, 100 × 10−3 mw at 45° and 40 × 10−3 mw, respectively. Consequently, the percentage of absorbed light is 21.76%. The denaturation temperature of the fish corneal stroma is 22.27 °C. Conclusions: The method for obtaining fish collagen affects the specific properties of collagen and consequently its further uses as a potential biomedical substituent for mammalian collagen. Specification of the fish species and tissue type is crucial in identifying the quality as well as the physical and functional properties of the extracted collagen. [ABSTRACT FROM AUTHOR]

It is widely believed that a significant portion of the gut microbiota, which play crucial roles in overall health and disease, originates from the food we consume. Sashimi is a type of popular raw seafood cuisine. Its microbiome, however, remained to be thoroughly explored. The objective of this study is to explore the microbiome composition in sashimi at the time when it is served and ready to be eaten. Specifically, our tasks include investigating the diversity and characteristics of microbial profiles in sashimi with respect to the fish types. We utilized the Sanger-sequencing based DNA barcoding technology for fish species authentication and next-generation sequencing for sashimi microbiome profiling. We investigated the microbiome profiles of amberjack, cobia, salmon, tuna and tilapia sashimi, which were all identified using the MT-CO1 DNA sequences regardless of their menu offering names. Chao1 and Shannon indexes, as well as Bray–Curtis dissimilarity index were used to evaluate the alpha and beta diversities of sashimi microbiome. We successfully validated our previous observation that tilapia sashimi has a significantly higher proportions of Pseudomonas compared to other fish sashimi, using independent samples (P = 0.0010). Salmon sashimi exhibited a notably higher Chao1 index in its microbiome in contrast to other fish species (P = 0.0031), indicating a richer and more diverse microbial ecosystem. Non-Metric Multidimensional Scaling (NMDS) based on Bray–Curtis dissimilarity index revealed distinct clusters of microbiome profiles with respect to fish types. Microbiome similarity was notably observed between amberjack and tuna, as well as cobia and salmon. The relationship of microbiome similarity can be depicted as a tree which resembles partly the phylogenetic tree of host species, emphasizing the close relationship between host evolution and microbial composition. Moreover, salmon exhibited a pronounced relative abundance of the Photobacterium genus, significantly surpassing tuna (P = 0.0079), observed consistently across various restaurant sources. In conclusion, microbiome composition of Pseudomonas is significantly higher in tilapia sashimi than in other fish sashimi. Salmon sashimi has the highest diversity of microbiome among all fish sashimi that we analyzed. The level of Photobacterium is significantly higher in salmon than in tuna across all the restaurants we surveyed. These findings provide critical insights into the intricate relationship between the host evolution and the microbial composition. These discoveries deepen our understanding of sashimi microbiota, facilitating our decision in selecting raw seafood. [ABSTRACT FROM AUTHOR]

In this study, the muscle composition (approximate composition, amino acids, fatty acids) of frozen tilapia fillets undergoing temperature fluctuations (0, 1, 2, 3, 5, 7, 9 times) was simulated for nutritional evaluation using high performance liquid chromatography and gas chromatography. The results showed that moisture (79.5%~81.0%), crude protein (15.8%~18.0%), crude fat (3.2%~4.0%) and ash (0.75%~1.5%) in frozen tilapia fillets did not change significantly during temperature fluctuation (P > 0.05),the seven essential amino acids and polyunsaturated fatty acids decreased with the increase of the number of fluctuating cycles, monounsaturated fatty acids did not change significantly. Eicosapentaenoic and docosahexaenoic acids were decreased with increasing number of temperature fluctuations. It appeared that oxidation processes during temperature fluctuations contributed to the decline in quality of tilapia fillets. In conclusion, the nutritional quality of tilapia is decreased, but it is still a good source of high-quality protein and unsaturated fatty acids. The findings offer choices for consumers freezing food at home as well as a theoretical approach for the transportation and sales of tilapia industrial enterprises. [ABSTRACT FROM AUTHOR]

Co-infection with pathogenic microorganisms has substantial harmful effects on susceptible host organisms. It may influence disease progression and severity via synergistic and, in rare cases, antagonistic interactions. Therefore, sick fish are more prone to acquire infections and disseminate them to other neighboring species. Several studies have been conducted regarding the existence and impact of co-infections of bacteria, parasites, fungi, and viruses in different tilapia species. However, the effect and role of parasitic co-infections in farmed tilapia have not been fully addressed and need further investigation. Thus, this review aims to discuss various aspects of pathogenic parasitic and other microbial co-infections, the mode of transmission of major parasites, and the ecological impacts of the parasites affecting farmed tilapia species worldwide. Co-infections have a significant impact in aquaculture and may influence the development and severity of various fish diseases. Nevertheless, information regarding the underlying pathogenic mechanisms and microbial associations that emerge during these co-infections is scarce. In many cases, a prominent pathogen is believed to be critical and is thus recommended for treatment, while the co-infecting agents are ignored, which may worsen the case. This review also highlights other ways to raise awareness of co-infections and assist scientists and fish health inspectors in paying more attention to the natural occurrence of co-infections. This will result in further investigation and the continuous diagnosis of co-infectious events to maximize treatment practices to save tilapia that have been infected with parasites that cause co-infections. [ABSTRACT FROM AUTHOR]

The stocking and harvesting strategies used in aquaculture have a strong influence on the economic yields, and producers of aquatic species need alternatives that improve culture conditions and production economy. In this study, we used tilapia growth data from construct bioeconomic models to determine the best stocking and harvesting strategies under homogeneous (HM) and heterogeneous (HT) stocking sizes. We considered 180, 195, 210, and 225 days to harvest. Minimum marketable sizes (MMS) (minimum harvestable fish sizes) were defined according to the market as 350, 400, 450, and 500 g. The bioeconomic analysis considered a fixed price and a price that was variable depending on the size of the fish. With an average growth model and fixed price of USD$ 2.24 kg−1, independent of MMS, the economic results were negative under both HM and HT stocking and for all harvest times. With size-dependent variable pricing, the highest net benefit was generated by the 225-day, 500 g harvesting strategy, with USD$ 5061.91 per tank under HM and USD$ 5220.53 per tank under HT. Using quantile regressions and fixed pricing, the 225-day, 350 g strategy had the highest yield under HM and HT, with USD$ 4323.51 and USD$ 4190.90 per tank, while with variable pricing, the 225-day, 450 g strategy had higher yield in HM and HT, with USD$ 8634.03 per tank and USD$ 8983.26 per tank. Thus, growth modeling using quantile regression to approximate the population distribution suggested that HT stocking and size-dependent variable pricing generate higher yield for tilapia producers. [ABSTRACT FROM AUTHOR]

Introductions of non-native fish are intended to have positive social outcomes, although they can also result in negative environmental consequences. Recently, incidental introduction of tilapia (Oreochromis cf. niloticus) was recorded in the Kikori River, Papua New Guinea. This study investigated the abundance of Oreochromis cf. niloticus relative to native fish species in the Kikori Town market, and interviewed market vendors to gauge the local perception of Oreochromis cf. niloticus. Market data were collected over eight days with 1474 individual fish observed. Oreochromis cf. niloticus comprised 11.4% (n = 168) of fish and was the largest contributor of biomass (40.2%). Market vendors reported that Oreochromis cf. niloticus was easy to catch and sell, and ranked it highly in sale preference compared to native species. There is potential to explore export markets for Kikori River Oreochromis cf. niloticus in PNG's highland provinces to expand economic opportunities for local communities. [ABSTRACT FROM AUTHOR]

There is a growing body of evidence suggesting that water temperature can significantly impact the dietary fatty acid requirements of Nile tilapia (Oreochromis niloticus). Therefore, this study assessed the effectiveness of different dietary lipid sources on the growth performance of Nile tilapia reared at suboptimal temperatures. A network meta-analysis was performed, including searches of PubMed and Scopus from inception to January 2022, for trials that evaluated the effects of lipid sources on cold-stressed Nile tilapia. The Bayesian hierarchical framework was used to pool and compare the effect sizes of growth parameters such as weight gain, feed intake, and feed conversion ratio (FCR). Furthermore, the surface under the cumulative ranking curve (SUCRA) was obtained to calculate the probability that each lipid source was the most effective against cold stress. All subsequent numbers refer to comparisons with diets containing only fish oil. Dietary Aurantiochytrium significantly increased weight gain (SMD = 2.00, CrI: 0.70 to 3.40). In contrast, diets containing coconut oil led to significantly lower weight gain (SMD = − 3.30, CrI: − 6.00 to − 0.63) and higher FCR (SMD = 17.0, CrI: 6.70 to 27.0). Additionally, dietary corn oil was associated with a decrease in feed intake (SMD = − 2.32, CrI: − 3.91 to − 0.80), while a combination of fish and corn oil reduced FCR (SMD = − 5.70, CrI: − 11.0 to − 0.81). In general, the analysis of SUCRA values revealed that in cold-stressed Nile tilapia, Aurantiochytrium, sunflower oil, and the combination of fish and corn oil were the most effective lipid sources for improving growth at suboptimal temperatures. The results of the current study can serve as a basis for future studies that focus on the use of dietary lipid sources to mitigate cold stress in Nile tilapia. [ABSTRACT FROM AUTHOR]

Tilapia skin is a byproduct of tilapia processing and can be used as a potential resource to produce antioxidant peptides. In this study, the process conditions for the extraction of antioxidant peptides were optimized by response surface methodology, followed by amino acid and structural characterization of different antioxidant active fractions, and finally, the oxidative free radical scavenging mechanism was predicted. The enzymolysis process conditions are: enzyme dosage: 2.51% (w/w), temperature: 51 °C, solid‒liquid ratio: 1:50 (mg/mL), time: 9 h, and pH 10. Under these conditions, the IC50 values of the DPPH, ABTS and hydroxyl radical scavenging capacity of peptides were 6.81 ± 0.06, 9.69 ± 0.04 and 14.35 ± 0.04 mg/mL, respectively. Six fractions with different antioxidant activities were obtained after separation and purification. Amino acid analysis indicated that high proportions of hydrophobic amino acids (Val, Leu and Pro) and aromatic amino acids (Phe and Tyr) played an important role in enhancing the free radical scavenging activity of the peptides. FTIR and CD spectroscopy analysis showed that the higher proportion of α-helices and lower proportion of random coils in the peptide structure were the main reasons for the excellent antioxidant activity. The analysis of the free radical scavenging mechanism suggested that the OH and SH groups contained in Pro, Tyr and Met play an important role in free radical scavenging. These findings not only provide theoretical basis for the study of the structure–activity relationship of antioxidant peptides, but also provide technical support for relevant processing enterprises to improve the production and utilization efficiency of tilapia skin peptides. [ABSTRACT FROM AUTHOR]

To study genetic variation in Indian populations of tilapia, Oreochromis niloticus, both truss morphometrics and genetic characterization have been performed. In the present study, 88 individuals from two farm populations (GIFT and West Bengal) and one reservoir population (Gujarat) were selected to analyse variations at ten morphometric landmarks and eight microsatellite loci. Truss morphometric analysis showed PCI, PCII, and PCIII expressing 29.1%, 21.36%, and 15.48% of the variance, respectively. Results showed no clear shift in shape between the studied populations of O. niloticus, indicating low morphological variability among them. The number of microsatellite alleles ranged from 3 to 9, while expected heterozygosity (HE) and observed heterozygosity (HO) values ranged from 0.56 (WB) to 0.68 (Guj) and 0.59 (GIFT) to 0.72 (Guj), respectively. The Gujarat and West Bengal populations had the smallest pairwise distance (0.0123) between them, indicating that they were genetically closer. Individuals from GIFT, however, showed the largest distance from the other populations. DNA marker variations revealed the highest genetic variability in the Gujarat population and the lowest variability in the GIFT population. The results of this study will help establish a base population for genetic improvement program and conservation of wild populations. [ABSTRACT FROM AUTHOR]

During January 2013, a mining spill occurred in the Santa Maria mining region, releasing around 300,000 m3 of tailings on Los Remedios river, which was transported through the San Lorenzo river and finally to El Comedero (EC) dam. Twenty months later, we examined the concentrations of Hg and Se in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) captured in the EC dam to assess the performance of the cleaning operations. A high Se concentration in the liver of all species (carp, 1.2 ± 0.4; tilapia, 3.9 ± 2.1; bass, 3.5 ± 1.1 µg g−1 ww) was consistently observed, while this behavior was only found in the blue tilapia for Hg (0.15 ± 0.11 µg g−1 ww). Tilapia (benthic-detritivorous) exhibited the highest Se concentrations compared to the carp (omnivore) and the largemouth bass (piscivore). In contrast, the largemouth bass had the highest Hg levels in the muscle compared with the other fishes. Such differences could be related to the different metabolism and feeding habits among species. Compared to a tilapia study carried out three months after the mine spill during a mortality event, a decrease was evident in the liver for Se and Hg by 7.2 and 4.7 times, respectively. This reveals that cleaning operations were more efficient for Se and less for Hg, and that a prolonged period was required for the partial recovery of the element levels in fish from sites impacted by mining. Considering the Mexican consumption scenarios for each fish species, it could be concluded that there will be no non-cancer risk by exposure to Hg or Se. [ABSTRACT FROM AUTHOR]

The human-mediated transfers of tilapia for aquaculture as a panacea for food insecurity in Africa have led to unprecedented and irreversible impacts on native ichthyofaunal biodiversity. Though aquaculture has been pointed to as the main gateway to species introductions in the Pangani system, formal documentation on how it has contributed to such colonization is anecdotal. The present study aimed to genetically identify, update the list of introduced tilapia taxa, and authenticate if aquaculture is the main gateway to their widespread. We genetically identified non-native tilapias from the Pangani Catchment and aquaculture facilities by genotyping partial Mitochondrial DNA Control region. Molecular analyses depicted the Pangani Catchment to be exclusively inhabited by six non-native tilapiine taxa, particularly Oreochromis niloticus, Oreochromis leucostictus, Coptodon rendalli, Oreochromis esculentus, Oreochromis spilurus, and Oreochromis urolepis hornorum. Oreochromis niloticus, O. leucostictus, and C. rendalli were also predominant in aquaculture and shared haplotypes with their counterparts from the Pangani Catchment. We identified commercial strains of O. niloticus that also shared haplotypes between the two systems. Such haplotype sharing proves aquaculture is the gateway to introducing non-native tilapias into the Pangani Catchment. Thus, fish farming in the region should adhere to regional and international legislation to prevent future spillage. [ABSTRACT FROM AUTHOR]

E-commerce platforms have become a significant sales channel for processed tilapia products such as frozen tilapia fillets, pickled tilapia, and canned tilapia in China. As food safety issues are worldwide concerned, the imbalance between the nutritional benefits of fish and the risk of contamination has become a major constraint on fish consumption. Therefore, it is necessary to assess the safety of tilapia products sold on e-commerce platforms. We conducted a quantitative benefit-risk assessment of arsenic and nutrient levels for tilapia products sold on Chinese e-commerce platforms using the hazard quotient (HQ). A total of 147 tilapia products were collected from the central Chinese e-commerce platforms Tmall, Taobao, and Jingdong for arsenic determination. Arsenic concentrations in tilapia products ranged from 0.004 to 0.820 mg·kg−1. The inorganic arsenic content of tilapia products was lower than the national limit (0.1 mg·kg−1). One-way analysis of variance revealed that there was no significant difference in arsenic levels in tilapia products among different regions (p > 0.05), while there was a significant difference in product form, with canned tilapia containing significantly higher arsenic levels than frozen tilapia fillets and pickled tilapia fillets (p < 0.05). We conducted an aquaculture experiment to analyze the nutrient levels of tilapia. The mean value of EPA + DHA content of tilapia was 20.634 mg·100 g−1. The HQ values of tilapia products ranged from 0.004 to 0.736. In a word, the nutritional benefits of consuming tilapia products exceed the risk of arsenic exposure. These data can help demonstrate that tilapia products are low-risk, high-yield nutritious food and provide relevant safety recommendations for consumers purchasing processed tilapia products online. [ABSTRACT FROM AUTHOR]

Species specificity of taste preferences supposes the ability of fish to consume food with particular taste and thus minimize feeding competition while sympatry. However, the problem of the extent to which taste preferences can be related to trophic category and phylogeny of fish has not been yet resolved. We evaluated the taste preferences in Mozambique tilapia Oreochromis mossambicus for 37 substances (amino acids, sugars, basic taste substances) that we used earlier in experiments with the Nile tilapia O. niloticus. In O. mossambicus, taste attractive substances are the least numerous (4) and substances with an indifferent taste predominate (25). In O. niloticus, the numbers of taste attractive and indifferent substances are nearly equal (20 and 17), while substances with repulsive taste were not found. The difference between these facultative phytophagous fish is most noticeable for sugars palatability: in O. mossambicus none of the sugars have attractive taste, and 6 of them evoke aversive responses. In opposite, 9 of sugars have attractive taste, while others are indifferent, and none of sugars decrease ingestion of flavoured agar pellets in O. niloticus. Nevertheless, many substances are arranged in a similar order in the rows ranked by palatability for these fish. The patterns of feeding behavior are almost the same in tilapias. The study highlights that the phylogenetic proximity and similarity in the trophic category does not lead to the similarity of fish taste preferences. Most probably, feeding competition in the historical past is the main force that triggers the divergence in fish taste system functionality. [ABSTRACT FROM AUTHOR]

The host immune response in Oreochromis mossambicus during natural infection with the isopod Cymothoa eremita was investigated. The naturally infected fishes were examined for enzyme profile, viz., respiratory burst activity (RBA), myeloperoxidase activity (MPO), and expression of immune-related genes, viz., toll-like receptor 22 (TLR 22), interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), complement component (C3), chemokine (CXCa), and β-actin in tissues of various organs (buccal cavity, gills and anterior kidney). Significant reduction (P < 0.05) in RBA and MPO was observed in the parasite-infected fishes when compared to the uninfected control fishes. In the buccal cavity, the expression of the immune-related genes was significantly (P < 0.05) upregulated, whereas all the genes except IL-1β were significantly (P < 0.05) upregulated in the anterior kidney. In the case of gill tissue, the expressed genes showed a varied type of regulation. The immunological responses in O. mossambicus during isopod infection have not been investigated in detail so far, and this is the first study unveiling such insights. Hence, this study will help to improve our molecular understanding of the host-immune response to parasitic isopod infection. [ABSTRACT FROM AUTHOR]

Contamination of fish with metals is a worldwide consumer safety concern. In this study, three metals such as arsenic (As), chromium (Cr), and lead (Pb) were measured in two commonly consumed fish species Oreochromis niloticus (Tilapia) and Pangasianodon hypophthalmus (Pangasius) that are commercially farmed. The concentration of the metals studied was found within the permissible limits. The concentrations of As, Cr, and Pb in tilapia fluctuated, ranging from not detected (ND) to 0.114 mg/kg, ND to 0.009 mg/kg, and ND to 0.085 mg/kg, respectively. For Pangasius, the concentrations were in the range of 0.014 to 0.118 mg/kg for As, ND to 0.02 mg/kg for Cr, and ND to 0.047 mg/kg for Pb. Hierarchical clustering revealed that As was possibly taken up by leachate and groundwater, while Cr and Pb were from contaminated feed. The results of the calculations for estimated daily intake, target hazard quotient, hazard index, and carcinogenic risk made it clear that consumption of the fish studied does not have a significant adverse effect on consumer health. In conclusion, the contamination levels of farmed tilapia and Pangasius sold in the study area are within acceptable limits, but regular monitoring is required to ensure safe production. [ABSTRACT FROM AUTHOR]

Background Antimicrobial peptides (AMPs), innate immune response molecules in organisms, are also known for their dual functionality, exemplified by hepcidin--an immunomodulator and iron regulator. Identifying and studying various AMPs from fish species can provide valuable insights into the immune profiles of aquaculturally significant fish, which can be made use of in its culture. Results Hepcidin, a dual-function antimicrobial peptide, was isolated from the gill tissue of Genetically Improved Farmed Tilapia (GIFT-Hep). GIFT-Hep consists of a 90 amino acid pre-propeptide with a 24-mer signal, a 40-mer propeptide, and a 26-mer mature peptide region. The mature peptide had a molecular weight of 3015.61 Da, a theoretical pI of 8.78, a net charge of +4.25, and a protein-binding potential of 2.06 kcal/mol. Four disulfide bonds were formed by eight cysteine residues in the mature region. The presence of positively charged arginine residues renders the peptide 50% hydrophobic. Molecular analysis of GIFT-Hep revealed the presence of a furin propeptide convertase motif, RX(K/R)R, which facilitates trimming of the peptide to yield the mature GIFT-Hep. The hypothetical iron regulatory sequence, QSHLSL, was also identified in the mature peptide. In silico predictions about the characteristics of GIFT-Hep, such as charge, hydrophobicity, high surface accessibility, transmembrane helical regions, hydrophobic faces, hot spots, and cell-penetrating properties, suggest that the peptide functions as an iron regulatory antimicrobial agent. Conclusions This study reports a hepcidin antimicrobial peptide with both HAMP1 and HAMP2 properties isolated from genetically improved farmed tilapia, and further evaluation of the properties will prove the feasibility of GIFT-Hep being used as a therapeutant in aquaculture. [ABSTRACT FROM AUTHOR]

Tilapia lake virus (TiLV) is a highly contagious viral pathogen that affects tilapia, a globally significant and affordable source of fish protein. To prevent the introduction and spread of TiLV and its impact, there is an urgent need for increased surveillance, improved biosecurity measures, and continuous development of effective diagnostic and rapid sequencing methods. In this study, we have developed a multiplexed RT-PCR assay that can amplify all ten complete genomic segments of TiLV from various sources of isolation. The amplicons generated using this approach were immediately subjected to real-time sequencing on the Nanopore system. By using this approach, we have recovered and assembled 10 TiLV genomes from total RNA extracted from naturally TiLV-infected tilapia fish, concentrated tilapia rearing water, and cell culture. Our phylogenetic analysis, consisting of more than 36 TiLV genomes from both newly sequenced and publicly available TiLV genomes, provides new insights into the high genetic diversity of TiLV. This work is an essential steppingstone towards integrating rapid and real-time Nanopore-based amplicon sequencing into routine genomic surveillance of TiLV, as well as future vaccine development. [ABSTRACT FROM AUTHOR]

In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different combinations of temperatures (20, 26 and 32 °C) and osmolalities (280, 330 and 420 mOsm/kg) for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188, but not Prl177, was suppressed at 20 °C. In SW fish, mRNA expression of prl188 increased with rising temperatures at lower osmolalities, while and prl177 decreased at 32 °C and higher osmolalities. In Prl cells of SW-acclimated tilapia incubated in hyperosmotic media, the expressions of Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4,decreased at 32 °C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32 °C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity. [ABSTRACT FROM AUTHOR]

The bioaccumulation of some heavy metals in coaster waters directly affects the ecosystem and human beings. Thus, the objectives of this study are to evaluate the interaction between fish and coastal water and assess the long-term implications of human consumption of some major organs obtained from Tilapia brevimanus and Euthynnus alletteratus. The study determined the concentrations of arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) in twenty coaster water samples collected from two points and in the muscle, gills, and intestine of ten pieces of Tilapia brevimanus and ten pieces of Euthynnus alletteratus using a Perkin Elmer Model 306 Atomic Absorption Spectrometer. Furthermore, the accumulation of these metals and the assessment of the long-term implications of human consumption of the designated organs of the two species types were performed. The statistical significance level of the obtained results was determined using the T-test analysis tool, which revealed that the distribution of the metals varies in different organs of the fish species. The levels of pollutants were higher in Tilapia brevimanus organs than in Euthynnus alletteratus. The contents of As, Cd, Cr, and Pb in the gills were higher than those in the muscle. Also, the metal pollution index in the organs followed the order of intestine > gills > muscle for both Tilapia brevimanus and Euthynnus alletteratus, posing serious health risks. [ABSTRACT FROM AUTHOR]