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Climate changes linked to extreme events pose a threat to freshwater biodiversity, impacting organs, behaviour, and reproduction. Moreover, these changes can be amplified by pollution. Copper sulphate (CuSO4) is used in agriculture and aquaculture, so the copper can reach streams, rivers, and lakes impacting fish. This study evaluated the combined effects of temperature and copper on gills and liver histology biomarkers and in the behaviour of Mozambique tilapia over 28 days. Tilapias were exposed to different water temperatures (25 °C and 32 °C) and CuSO4 concentrations (1.1 and 3.6 mg/L). Fish from the control group were exposed to water without copper sulphate and at 25 °C (within their optimum range). Histopathological analysis revealed significant tissue lesions, namely aneurysms and bending of gill lamellae, and hyalinization and vacuolization in the liver at the higher temperature and CuSO4 level. Moreover, behavioural observations revealed increased stress changes under the same conditions. These findings highlight the effects of fast climate change, and rising temperatures on copper toxicity, underlining the necessity for strict monitoring and regulation of copper use due to future climate change scenarios to protect aquatic ecosystems, ichthyofauna population and trophic web dynamics. This data also alerts for similar problems with other toxic metals or chemicals, at short term, in streams and rivers, under rapid climate changes and more frequent extreme events. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the toxic effects of benzalkonium chloride (BAC) on Oreochromis mossambicus, a freshwater fish species. Probit analysis was used to determine the lethal concentration (LC50) of BAC for different exposure periods (24, 48, 72, and 96 h). The viability of fish exposed to BAC was assessed using the general threshold survival models (GUTS) and confirmed with relevant datasets to evaluate model accuracy. Experimental groups of fish were exposed to BAC concentrations equivalent to 10% and 20% of the 96-h LC50 for 45 days. The study revealed significant alterations in various parameters during sublethal BAC exposure. These effects included decreased specific growth rate (SGR), red blood cell count (RBC), hemoglobin (Hb) concentration, hematocrit (Ht) value, plasma protein, and albumin levels, as well as acetylcholinesterase (AChE) activities in both gills and liver. Additionally, an increase in gastrosomatic index (GSI), feed conversion ratio (FCR), plasma glucose and creatinine concentrations, alanine aminotransferase (ALT), aspartate aminotransferase (AST) enzymatic activities, catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) levels were observed in the exposed fish's gills and liver. Furthermore, the study found that glutathione S-transferase (GST) and glutathione peroxidase (GPx) levels initially increased and then decreased in both gills and liver after exposure to BAC. Correlation matrix analysis, multivariate multiple regression (MMR), canonical correspondence analysis (CCA), integrated biomarker response (IBR), and biomarker response index (BRI) were utilized to assess the impact of BAC on fish, highlighting significant effects on multiple biomarkers in O. mossambicus following surfactant exposure. Thus, the study provides valuable insights into the toxic effects of BAC on this fish species, emphasizing the importance of monitoring such pollutants in aquatic environments. [ABSTRACT FROM AUTHOR]

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Simple Summary: This study evaluated the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology, intestinal microbiota and stress resistance in juvenile hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). It is concluded that organic silicon had no negative effects on the physiology and metabolism of the fish. The results showed that up to 50 mg·kg−1 of organic silicon can be applied to the diet of red Tilapia, improving digestive, metabolic and growth performance. The interactions between zootechnical performance, physiological digestive and metabolic capacity in hybrid red Tilapia still deserve further exploration. In recent decades, interest has been aroused worldwide in the use of silicon in nutrition; however, information on its effect on nutrition and metabolism of fish is limited. The objective of the research was to evaluate the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology and intestinal microbiota and stress resistance in hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). Methodologically, six levels of organic silicon (DOS) [control (0), 10, 20, 30, 40 and 50 mg·kg−1] were used to feed juvenile fish (initial weight 7.51 ± 0.25 g) grown for eight weeks in 18 aquariums (15 fish/aquarium). The results indicated that growth performance showed differences (p < 0.05) for specific growth rate, feed conversion and survival. Triglycerides, cholesterol and glucose, transaminases and digestive enzymes were significantly influenced by DOS levels. The histological study confirmed that the administered diets did not cause damage and induced significant morphological changes in the proximal intestine. The 16S rRNA gene sequencing analysis of the gut microbiota showed a high diversity and richness of OTU/Chao-1, with Fusobacteria, Proteobacteria, Bacteroidetes and Acidobacteria predominating in the DOS treatments compared to the control (p < 0.05). Induction of hypoxia stress after the feeding period showed a significant relative survival rate of 83.33% in fish fed 50 mg·kg−1. It is concluded that the DOS treatments performed better than the control treatment in most of the variables analysed. DOS had no negative effects on the fish. The results showed that up to 50 mg·kg−1 DOS improved digestive, metabolic and growth performance in hybrid Tilapia. [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]

The synthesis of silver nanoparticles has gained interest due to their diverse applications in various fields. It is very essential to use capping agents to avoid loss of nanosized characteristics due to agglomeration of AgNPs. In the present investigation, a simple and environmentally viable protocol to synthesize a wide range of concentrations of non-agglomerated and colloidal AgNPs using extracts of discarded wastes (gills and intestine) of Tilapia (Oreochromis mossambicus) in three different aqueous media without the requirement of any additional stabilizing and capping agent is described. The size of most of AgNPs ranged from 2 to 20 nm, followed by sizes of 20–40 nm and some with sizes of 40–50 nm. Zeta potential was in the range of −31.1 to −52.8 mV and −33.3 to −53.6 mV, and surface plasmon resonance ranged from 405 to 410 nm for gill and intestine extracts respectively. HR-TEM images indicated that Phosphate buffer saline is the best suitable for synthesizing non-agglomerated AgNPs capped with biomolecules. Valorization has been achieved by trapping Ag NPs into two different forms of natural zeolites namely stilbite and mordenite and their ammonia removal efficiency have been evaluated. In addition, the antimicrobial activity of synthesized AgNPs and their valorized products exhibited potent inhibitory activity against test bacteria such as Escherichia coli and Aeromonas hydrophila. This study not only establishes a simple and environmentally viable protocol for the synthesis of AgNPs and valorized products for environmental and disease management but also adds to the utilization of fish wastes in solid waste management. [ABSTRACT FROM AUTHOR]

Recent research has raised concern about the biocompatibility of iron oxide nanoparticles (IONPs), as they have been reported to induce oxidative stress and inflammatory responses, whilst prolonged exposure to high IONP concentrations may lead to cyto-/genotoxicity. Besides, there is concern about its environmental impact. The aim of our study was to investigate the effects of IONPs on the antioxidant defence system in freshwater fish Mozambique tilapia (Oreochromis mossambicus, Peters 1852). The fish were exposed to IONP concentration of 15 mg/L over 1, 3, 4, 15, 30, and 60 days and the findings compared to a control, unexposed group. In addition, we followed up the fish for 60 days after exposure had stopped to estimate the stability of oxidative stress induced by IONPs. Exposure affected the activity of antioxidant and marker enzymes and increased the levels of hydrogen peroxide and lipid peroxidation in the gill, liver, and brain tissues of the fish. Even after 60 days of depuration, adverse effects remained, indicating long-term nanotoxicity. Moreover, IONPs accumulated in the gill, liver, and brain tissues. Our findings underscore the potential health risks posed to non-target organisms in the environment, and it is imperative to establish appropriate guidelines for safe handling and disposal of IONPs to protect the aquatic environment. [ABSTRACT FROM AUTHOR]

In the study, papain was used to hydrolyze tilapia (Oreochromis mossambicus) skin to obtain a tilapia skin hydrolysate (TSH) with dual angiotensin‐converting enzyme (ACE) and dipeptidyl peptidase IV (DPP‐IV) inhibitory activities. The resulting TSH was sequentially fractionated by ultrafiltration, size exclusion separation chromatography, and reverse‐phase high‐performance liquid chromatography. Its inhibitory effects on ACE and DPP‐IV were determined by commercial reagent kits. Two peptides purified from TSH were identified as Gly‐Pro‐Leu‐Gly‐Ala‐Leu (GPLGAL) and Lys‐Pro‐Ala‐Gly‐Asn (KPAGN) by the ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). Inhibitory concentration (IC50) of GPLGAL on ACE and DPP‐IV were 117.20 ± 1.69 and 187.10 ± 2.75 µM, respectively. IC50 of KPAGN on ACE and DPP‐IV were 137.40 ± 2.33 and 259.20 ± 2.85 µM, respectively. The molecular simulation demonstrated that the binding affinities of GPLGAL to ACE and DPP‐IV proteins were −8.5 and −7.4 kcal/mol, respectively, whereas those of KPAGN to ACE and DPP‐IV proteins were −7.9 and −6.7 kcal/mol, respectively. GPLGAL interacted with 21 amino acid residues of the ACE active site, whereas KPAGN engaged with 19 amino acid residues. Additionally, GPLGAL interacted with 10 amino acid residues of the DPP‐IV active site, whereas KPAGN engaged with 13 amino acid residues. The two peptides predominantly occupied the active sites of ACE (His513, Tyr523, and Ala354) and DPP‐IV (Tyr662 and Arg125) through hydrogen bonding. This leads to the deactivation of ACE and DPP‐IV. Practical Application: Accelerate tilapia skin development and high‐value utilization; provide foundation for preparing the peptides with dual ACE and DPP‐IV inhibiting activity. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is an anthropogenic chemical compound utilized to manufacture a wide range of consumer products, such as polycarbonate, polyvinyl chloride (PVC), food packages, and thermal papers. Because of its extensive worldwide use, BPA is pervasive in the environment, negatively affecting aquatic life. Therefore, we studied the occurrence, persistence, and ecological risk of BPA in surface water receiving raw leachate from a municipal solid waste (MSW) open dump in Kerawalapitiya, Sri Lanka. Our findings corroborate that the BPA average concentrations in the canal network were 0.4–42.6 µg/L during the wet season and 0.2–4.9 µg/L during the dry season. The levels of BPA at 11 locations (out of 16) during both seasons differed significantly from the upstream sample, where there was no impact from the dump site (p < 0.05), indicating the ubiquitous occurrence and persistence of BPA in the canal network. BPA levels in the waterbodies are greater in the wet period than in the dry period because of the continuous ingress of run‐off‐driven leachate to the canal network. Our study infers that pH and salinity correlate positively with BPA, while temperature, DO, and TSS are negatively correlated with BPA. BPA levels in five locations during the wet season and one during the dry season surpassed the tolerable level of BPA stipulated by the Canadian Federal Environmental Quality Guidelines to safeguard aquatic life, which is 3.5 µg/L. The findings of the acute ecological risk assessment articulate that during the wet season, Mozambique tilapia (Oreochromis mossambicus) and orange chromide (Etroplus maculatus) constitute a high acute risk, while they pose a medium acute risk during the dry season. Our study suggests that the relevant authorities must prevent the ingress of runoff rich with BPA onto the canal network to protect aquatic life. [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]

The current study aimed to evaluate growth performance, digestive enzyme activities, antioxidant status, nonspecific immune response and intestinal histological status of red tilapia fed Daphnia meal (DM) as a substitute for fishmeal (FM). Hybrid red tilapia (Oreochromis mossambicus × Oreochromis aureus) fry (0.54 ± 0.05 g fish−1) was allocated in nylon haba cages (100 fry m−3) for 2 weeks as an acclimation period. The fish were divided into five groups (three replicates each). The experimental diets were prepared by replacing FM with DM at concentrations of 25%, 50%, 75% and 100% respectively. The results indicated that fish fed increasing levels of DM (50%–75%) experienced high growth performance, feed utilisation and protein content. The activities of digestive enzymes were significantly increased in all groups fed DM diets compared to the control. The antioxidant balance was improved by decreasing the level of malondialdehyde and increased the total antioxidant capacity, catalase, superoxide dismutase and glutathione reductase activities in the liver of fish fed DM. The nonspecific immune response, including lysozyme, alkaline phosphatase activities and total protein level improved significantly with increasing FM substitution levels by DM in a dose‐dependent manner. Histometric analysis of the intestinal wall revealed an increase in the villus length, crypts depth and goblet cells number in groups fed DM meal up to 50% substitution level compared to other treatments. It may be concluded from results of this feeding trial that in the aquaculture of hybrid tilapia, FM may be substituted with up to 50% DM without compromising intestinal health, growth performance and immune status of the fish. [ABSTRACT FROM AUTHOR]

Urotensin-I (UI) is a peptide belonging to the corticotropin-releasing hormone family, produced in the urophysis of teleosts. This investigation was undertaken to examine the effect of UI on the hypothalamo-hypophysealovarian axis in the Mozambique tilapia, a cichlid fish. In the first experiment, administration of UI (2 μg/100 μL saline) for 22 days caused a significant reduction in the number of follicles at stages I, II, III (previtellogenic), IV (vitellogenic), and V (preovulatory), concomitant with a significant increase in the percent atresia of follicles at stages II, III, and IV than in controls. In the pituitary, gonadotropin-releasing hormone (GnRH) - positive fibres were detected in the proximal pars distalis (PPD) in both controls and UI-treated fish; however, there was a significant reduction in the intensity and percent area of GnRH-immunoreactive fibres in fish treated with UI compared with controls. The serum luteinizing hormone (LH) level was significantly lower, whereas a significant rise in the serum level of cortisol was noticed in UI-treated fish compared with controls. In the second experiment, treatment with a low dose of UI (10 mM) did not affect the number of ACTH-secreting cells in vitro, but the number of these cells was significantly higher in high-dose UI (50 mM)-treated pituitaries compared to controls. Together, the present investigation reveals for the first time that the treatment of UI affects the follicular development process through the downregulation of the GnRH-LH axis and activation of the pituitary-interrenal pathway in teleosts. [ABSTRACT FROM AUTHOR]

Insect-based meals have emerged as a viable global scale alternative to fish meal in aquafeed. This is mainly due to their high protein content, balanced amino acid composition, and fatty acid profile, which closely resembles that of fish meal. An 8-week trial was conducted to evaluate the growth performance, blood serum chemistry, and histomorphology of Mozambique tilapia (Oreochromis mossambicus) fed diets containing soldier termite meal as a partial substitute for fish meal. Five isonitrogenous, isolipidic, and isocaloric diets were formulated to partially replace fish meal with soldier termite meal at 0, 10, 30, 50, and 70%, labelled as D1, D2, D3, D4, and D5, respectively. The study showed that soldier termite meal could replace fish meal up to a 50% inclusion level. The growth performance and nutrient utilisation of fish fed diet D4 (50%) were comparable to fish fed the control diet. Fish fed the diet with the highest proportion of soldier termite meal (70%) showed significantly higher alanine aminotransferase and aspartate aminotransferase levels (P < 0.05). Cholesterol, triglyceride, and glucose levels were not influenced by the inclusion of soldier termite meal in the diet of Mozambique tilapia (P > 0.05). The histomorphological examination of the intestines revealed no discernible alterations. The current study has demonstrated that soldier termite meal can replace fish meal up to 50% of the feed content without inducing adverse effects on growth performance and health status of O. mossambicus. The cost-benefit analysis showed that substituting fish meal with soldier termite meal was economically sustainable. [ABSTRACT FROM AUTHOR]

The present work aimed to investigate the impacts of tank color (transparent, light blue, and red), feed pellet types (floating and sinking), and their interaction on the performance and welfare of red hybrid tilapia juveniles with an initial average weight of 19.59 g for a 50 day trial period following a 3 × 2 factorial design. Fish were cultured randomly at a stoking rate of 10 juveniles/100‐L tank. Fish were fed 6 days per week at a rate of 4% biomass twice daily. Three replicates were performed for each measurement. A two‐way analysis of variance showed that using tanks of different colors (transparent, light blue, and red) has no impact on the growth, feed efficacy, survival rate, and blood composition (except for red blood cells, hematocrit, and triglycerides) of tilapia. Also, pellet types (floating and sinking) showed no significant alterations for the above variables except for glucose and hematocrit levels. Interestingly, the interaction between tank color and pellet type exhibited significant impacts on growth parameters, feed utilization, blood variables, and intestinal enzymes of red hybrid tilapia. Moreover, fish reared in transparent or light blue tanks and fed with floating diets performed the best for all evaluated parameters. Additionally, sinking pellets had better effects when combined with red (dark)‐colored tanks. [ABSTRACT FROM AUTHOR]

The rapid development of nanotechnology needs to study the toxic effects of nanoparticles. Aluminium oxide (AL2O3 NPs) is inevitable metal oxide nanoparticles has multiple applications in various fields. The impact of AL2O3 NPs on the aquatic system is very scarce. Thus, the aim of the present study was designed to evaluate the toxic effect of AL2O3 NPs on freshwater fish Oreochromis mossambicus. The AL2O3 was synthesized by simple sol-gel method and characterized by UVspectroscopy, FT-IR, X-ray diffraction (XRD) and SEM with EDX. Further, synthesized and characterized AL2O3 nanoparticles were orally introduced to the fish Oreochromis mossambicus in sub-lethal doses of (3.3, 5, 10 mg/kg body weight) for the period of 7 days. The haematological (Hb, RBC, WBC, HCT, MCV, MCH, MCHC) indices and tissue damaging enzymes (GOT and GPT) activity were observed in gill, liver and muscle tissues of treated fishes. The results revealed that synthesized AL2O3 NPs induced significant (P< 0.05) alterations in haematology and increased (P< 0.05) GOT and GPT activity in fish at tested doses. The current study gives an insight into the toxic effect of AL2O3 NPs on freshwater fish O. mossambicus and also demonstrates that manufactured metal oxide NPs may pose potential risk to the environment and to human populations. [ABSTRACT FROM AUTHOR]

BACKGROUND: Aquatic products are rich in nutrients and unique in flavor, and are popular among the public. However, aquatic products are extremely susceptible to quality degradation during storage, of which odor deterioration is the most obvious and influential aspect. Odor deterioration in aquatic products is widespread and severely affects overall flavor and quality. In this study, odor deterioration and flavor-related quality degradation of tilapia during cold storage are discussed, focusing on the changes in volatile compounds and the evolution of free fatty acids (FFAs), free amino acids (FAAs), nucleotides, and microbial diversity. RESULTS: A total of 63 volatile compounds were detected by gas chromatography--mass spectrometry, including 11 hydrocarbons, 10 alcohols, 6 aldehydes, 8 ketones, 6 esters, 9 aromatics, 3 phenols, and 10 other compounds. Microbial diversity analysis revealed that Acinetobacter, Psychrobacter, Vagococcus, and Myroides were the main dominant species of tilapia at the end of cold storage and predicted that microorganisms could influence the flavor of tilapia by participating in important metabolic pathways. Meanwhile, the evolution of FFAs, FAAs, and nucleotides also had a significant impact on odor deterioration, as evidenced by the contribution of unsaturated fatty acids (such as oleic acid and linoleic acid), Lys, and off-flavor nucleotides (HxR and Hx) to the undesirable flavor. Oxidation of oleic acid and linoleic acid resulted in changes in aldehydes, with Lys, HxR, and Hx being key flavor precursors and off-flavor contributors. CONCLUSION: This study contributes to a comprehensive overview of odor deterioration and the evolution of flavor-related quality in tilapia during cold storage, providing new insights into the regulation of overall flavor and quality. [ABSTRACT FROM AUTHOR]

Invasive non-native freshwater fishes have long been recognized as a threat to biodiversity conservation and management. Non-native fishes with a high risk of becoming invasive can be identified using risk screening tools. Here, we used the Aquatic Species Invasiveness Screening Kit (AS-ISK) to identify the invasion risk of non-native fishes in Yunnan Province, China. AS-ISK scores were calibrated to distinguish between species with high and low-to-medium risks of invasiveness. Risk threshold was 17.25 for BRA (Basic Risk Assessment) and BRA+CCA (BRA+ Climate Change Assessment) in Yunnan Province. Based on BRA scores, 21 of the 37 screened species were classified as high risk, 13 as medium risk and 3 as low risk. Based on BRA+CCA scores, 22 of the 37 screened species were classified as high risk, 12 as medium risk and 3 as low risk. For both BRA and BRA+CCA, the highest-scoring species were Hypostomus plecostomus, Oreochromis aureus, Oreochromis mossambicus and Oreochromis niloticus. This study reliably assessed the risk of non-native fish invasion in Yunnan Province and identified priority non-native fishes for prevention and control, providing information for targeted monitoring and management decisions in the region. [ABSTRACT FROM AUTHOR]

Background: The level of diversity has a crucial role in the stability of the ecosystem. The higher the variety, the more stable an ecosystem, including agricultural land cultivated by farmers. Increasing of population affected the higher demanding of community towards their consumption activities. Especially, the natural resources that comes from local area such as Sukamaju District. Biodiversity of resources urgently needed to preserve the ecosystems meanwhile being the potential source to fulfilled nourishment of the people. This study aims to determine the diversity of peatland ecosystems by using a purposive sampling method in every selection of subject groups based on the characteristics or characteristics of a specific population. Methods: Field and Laboratory activities are needed in this research. Sample collection using several methods according to the targeted sample. Most of the sample using purposive sampling but also line intercept transect method. Fish sampling used a fishing gear called a gill net with a mesh size of 2-7 inches. The fish caught is placed in a labeled coolbox. Insect collection was running in the morning at 07.00-11.00 and in the afternoon at 3-5 pm (UTC+09:00). Sampling is held once a month for three months at predetermined coordinate points. Diversity was analyzed using Shannon-Wienner diversity, evenness index, dominance index and intensity on peatlands. Result: The results found seven orders and 30 families, with a total population of 1,231 individuals. The most dominant types of insects are the orders Coleoptera, Hemiptera and Lepidoptera. High diversity index (H'=3.021), high evenness index (E=0.86243) and low dominance index (D=0.3101). Fish community structure obtained diversity index (H') included in the medium category, for uniformity values in the high class and dominance index values in the low sort. The dominant fish species found were Channa striata, Anabas testudineus, Lates calcalifer, Mugil cephalus, Plotosus papuensis and Toxotes chataerus, while Oreochromis niloticus, Oreochromis mossambicus, Hexanematichthys sagor and Megalops cyprinoides. While the types of molluscs found to have the highest abundance were Pila ampullacea, Pomacea canaliculata and Pilsbryoconcha exilis. [ABSTRACT FROM AUTHOR]

The palatability of L-α- and D-α-isomers of alanine, aspartic and glutamic acids, and tryptophan, as well as L-α- and L-β-isomers of alanine for the Mozambique and Nile tilapias (Oreochromis mossambicus and O. niloticus, respectively), golden mbuna Melanochromisauratus, lemon cichlid Neolamprologus leleupi, and the tailbar cichlid Vieja hartwegi has been compared. Consumption of agar-agar pellets with L-α- and D‑α-isomers of aspartic and glutamic acids and tryptophan differs in Mozambique tilapia and tailbar cichlid, pellets with alanine and tryptophan, in golden mbuna, with aspartic acid and tryptophan, in lemon cichlid, and with aspartic acid, in Nile tilapia. The palatability of L-α- and L-β-isomers of alanine is significantly different for the Mozambique tilapia, lemon cichlid and tailbar cichlid. The feeding behavior exhibited by cichlids during orosensory testing of pellets is similar and little depends on the palatability of the pellets. All cichlids make a small number of rejections and repeated grasps of pellets; most cichlids retain pellets in the oral cavity many times longer in experiments that ended by consumption. The different taste properties of optical and structural isomers of amino acids for the studied cichlids confirm the species specificity of taste preferences in fish and indicate the importance of these substances as chemical regulators of trophic relationships in aquatic communities. [ABSTRACT FROM AUTHOR]

Aquaculture is an important sector for ensuring global food security. Due to the scarcity of freshwater available for expanding aquaculture, the development of omnivorous fish species and varieties that can tolerate high salinity will enhance fish production. Some tilapia species are good candidates for aquaculture in brackish and seawater because they can grow in high salinity. Among tilapia species, Oreochromis mossambicus, Oreochromis aureus, Oreochromis spilurus, Oreochromis urolepis hornorum, Sarotherodon galilaeus and Coptodon zillii are the most salinity‐tolerant. Hybrids derived from salinity‐tolerant tilapia species are tolerant to a certain level of salinity. They have been used in aquaculture production in brackish water and full seawater. Conventional selective breeding has been applied to increase the growth rate of salinity‐tolerant tilapias. However, their growth rate is lower than that of the freshwater Oreochromis niloticus. Recently, many genomic resources and tools have been developed for salinity‐tolerant tilapia. Quantitative trait locus (QTL) mapping and genome‐wide association studies (GWAS) for important economic traits, including salinity tolerance and other desired traits, have been carried out and applied in molecular breeding for superior salinity‐tolerant tilapia lines. In this review, we systematically analysed tilapia species that can be cultured in brackish and saltwater. We summarized previous works in conventional breeding and molecular breeding for salinity‐tolerant tilapia. We pointed out a few known and potential challenges in the selective breeding and culture of salinity‐tolerant tilapia. Due to the rapid advances in molecular and other disruptive technologies, we are optimistic that novel breeding approaches will significantly increase the production salinity‐tolerant tilapia. [ABSTRACT FROM AUTHOR]

Macrobrachium rosenbergii holds significant importance in aquaculture within tropical and subtropical regions globally. An infection called infectious precocity virus disease (IPVD), caused by infectious precocity virus (IPV), has emerged in M. rosenbergii in China and causes significant economic losses. The diseased M. rosenbergii presents with the characteristics of sexual precocity and slow growth. Elaborating the route of transmission and host range of IPV is necessary to prevent the disease. Transmission of IPV to healthy M. rosenbergii can occur through the ingestion of IPV-infected tissue, immersion of viral filtrate, cohabitation with infected M. rosenbergii, or water-borne transmission in contaminated environment. Results showed that fertilized eggs and different growth and development stages (larvae Ⅰ–Ⅵ, postlarvae, juveniles, and adult prawns) from infected M. rosenbergii were negative for IPV, indicating that vertical transmissions did not occur. The results of artificial infection experiments showed that M. nipponense tested positive for the presence of IPV, but not in fishes Carassius auratus, Pangasius bocourti, Micropterus salmoides, and Oreochromis mossambicus, and crabs Scylla paramamosain and Eriocheir sinensis. IPV could cause slow growth in M. nipponense and mainly infected the second pereiopod, brain, eyes, and gills of M. nipponense. M. nipponense was found to be a new freshwater crustacean host for IPV. From December 2019 to March 2022, 260 M. nipponense samples in four regions were collected, including 230 M. nipponense IPV-positive samples according to nested PCR and 40 M. nipponense IPV-negative samples according to nested PCR. These findings could aid in preventing and managing IPV infections in crustaceans. [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]

Triclosan, a broad-spectrum antimicrobial agent, which is widely used in several pharmaceutical and personal care products, has been known to pose adverse impacts on various groups of aquatic organisms, including fish. The present study aimed to compare the sensitivity of five selected freshwater fishes toward triclosan exposure. The acute toxicity or median lethal concentration (LC50-96 h) of triclosan determined using probit analysis was 1.76 mg L−1 in Anabas testudineus, 448 µg L−1 in Danio rerio, 700 µg L−1 in Gambusia affinis, 1.35 mg L−1 in Oreochromis mossambicus, and 750 µg L−1 in Pseudetroplus maculatus. Based on the length–weight relationship, the lowest condition factor, or K value, was recorded in Danio rerio (0.931) while the highest value was observed in Anabas testudineus (2.343) indicating negative allometric growth. Similarly, the weight of fishes and gill weight declined significantly (p < 0.05) in their respective LC50-96 h groups with concomitant alterations in the rate of oxygen consumption denoting respiratory distress. Triclosan exposure also resulted in the modification of fish behavior and histomorphological damage in gill tissues. The alterations in all parameters tested were more prominent in Danio rerio and thus considered the most sensitive species, while Anabas testudineus comparatively tolerated the toxicant to some extent. The study provides the baseline data that variation in the length–weight relationship is one of the major factors that influences the toxic effects of triclosan on the selected freshwater fishes. [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]

This trial aimed to investigate whether dietary selenium form influenced the reproductive performance of red tilapia broodfish. Four experimental broodstock diets were prepared employing two types of selenium. The first diet was free of additives and acted as the control diet. While the other three formulated diets were supplemented with conventional selenium sources (sodium selenite, Na2SeO3; 1 mg/kg), selenium nanoparticles (NPSe, 1 mg/kg), or a combination of them (0.5 mg Na2SeO3/kg + 0.5 mg NPSe/kg), respectively. Twelve cement ponds (each 24 m2) were subjected to fish brooder experimental groups. Each pond received six prespawning females (mean initial weight, 60.9 ± 0.4 g) and two males (mean weight 80.3 ± 0.8 g) of red tilapia. Each formulated diet was supplied to three broodfish cement ponds, and the reproductive traits of 18 adult female fish were monitored over 25 weeks. The findings showed that female fish fed NPSe-enriched diets had significantly higher viscera, liver, and gonad weight than other experimental groups. At the same time, the highest levels of LH, progesterone, and estradiol-17β, as well as the lowest levels of FSH, were detected in fish fed the NPSe diet, followed by those on the Na2SeO3 + NPSe and Na2SeO3 diets, respectively. Furthermore, the diameter, weight, and volume of eggs, as well as the number and weight of larvae in red tilapia brooder fish fed the various dietary selenium forms, increased markedly (P < 0.001). Female red tilapia broodfish given selenium-based diets enhanced all spawning performance indicators (particularly total spawned egg per pond or fish and initial spawning interval) when compared to a control group fed an unsupplemented diet. Besides, as compared to other treatment groups, the spawning frequency of each female fish fed NPSe-supplemented diets (alone or in combination with Na2SeO3) was considerably (P < 0.001) promoted. The fish group fed NPSe alone or mixed with Na2SeO3 had a well-developed stroma structure, many mature vitellogenic and postvitellogenic oocytes, and a remarkable intensity of mature spermatozoa in the testis. In conclusion, incorporating NPse into red tilapia broodstock diets might be a safe and efficient way to enhance reproductive function and fry production. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the growth performance, feed utilisation, digestive and metabolic enzyme activity, and liver histology in juveniles of hybrid red tilapia (Oreochromis mossambicus × Oreochromis niloticus) fed with the inclusion of chitosan in their diet. Six dietary chitosan levels (0 "control", 10, 20, 30, 40, and 50 g kg−1) were used to feed juvenile fish (initial weight 7.50 ± 0.20 g) that were cultured for eight weeks in 18 tanks at a density of 15 fish/tank. The growth performance presented significant differences (p ˂ 0.05) for weight gain, specific growth rate, feed conversion ratio, hepatosomatic index, and survival rate. The digestive and metabolic enzyme activities were significantly (p < 0.05) influenced by the levels of chitosan in the administered diet. Histologically, no damage was found in the liver; however, morphometrically, a significant difference (p < 0.05) was found in the hepatocyte area and sinusoid area. Vacuolisation of hepatocytes was found in treatments with 40 and 50 g kg−1 of chitosan in the diet. Treatments with doses of chitosan showed a better response (p < 0.05) compared to the control treatment in most of the different groups of variables analysed. The result of the principal component analysis suggests that a diet containing 40 g kg−1 of chitosan is optimal for tilapia growth performance. [ABSTRACT FROM AUTHOR]

Invasive fish can profoundly affect communities they invade. In Hawai'i, invasive fishes have become established in many anchialine pools, threatening the persistence of resident invertebrates, including several endangered species. Tools to eradicate invasive fishes from these pools are lacking. This study tested the efficacy of carbon dioxide (CO2) gas diffused into anchialine pool water as a method to eradicate invasive Mozambique tilapia (Oreochromis mossambicus), guppies (Poecilia reticulata), and western mosquitofish (Gambusia affinis). We first conducted aquarium trials to identify how these fishes were affected by elevated CO2 and the concomitant reduction in pH. We then carried out field trials in pools containing these fish in one pool each at two national historical parks on the Island of Hawai'i during July 2021-January 2022. We also developed environmental DNA (eDNA) protocols to detect fish that may have survived CO2 treatments. The effect of CO2 on fish behavior varied among species; at pH 5.3 (CO2 = 255 mg/L) for tilapia and 5.0 (CO2 = 488 mg/L) for tilapia, guppies, and mosquitofish, all generally lost their ability to swim, showed slow or no gill movement, and altered their position in the water column. No tilapia survived the trials (n = 4 and 6 individuals at pH 5.3 and 5.0, respectively). In contrast, 41.7% (n = 12) of adult guppies and 66.7% (n = 12) of adult mosquitofish survived treatment at pH 5.0. In the field we were unable to reduce anchialine pool water pH below 5.7. Regardless, we were able to eradicate tilapia from one pool over four sequential treatments. Post-treatment eDNA assessments supported visual surveys, confirming our results. We were not able to eradicate guppies and mosquitofish. Results from this study show that CO2 can be an effective tool for eradicating invasive tilapia from anchialine pools, and post-treatment eDNA assessments can provide managers with a method for evaluating the success of eradication efforts. [ABSTRACT FROM AUTHOR]

The study was conducted to find out the morphological variations in tilapia (Oreochrmis mossambicus P. 1852) samples collected from three different water bodies namely Aanasagar lake (S1), Jaisamand lake (S2) and Vallabhsagar dam (S3) during the March 2012 to April 2022 have been studied in the current research. The standard-length and weight ranged between 17.50 to 38.50 cm and 98.50-932.50 g (S1), 15.00 to 24.00 cm and 60.00 to 250.00 g (S2), 15.00 to 33.00 cm and 77.00 to 662.00 g (S3). Key scales were picked out to accomplish the objective of research. The twelve different morpho-parameters (L1, L2,...L12) of Oreochrmis mossambicus P. 1852 scales were measured and analyzed to find presence or absence of morphological variations among the tilapia populations from three habitats. It was found that between these morphometric parameters of Oreochromis mossambicus, L3 and L8 in S1 (0.862), L7 and L12 in S2 (0.830) and L10 and L12 in S3 (0.988) showed very high correlation. Further, the morphological study on measurements was subjected to principal component analysis (PCA) and reported a total 84.98, 89.52 and 93.40 percent of significant variances in scale components (morphometric parameters) for tilapia from S1, S2 and S3 respectively. Variations obtained in morphological (morphometric measurements) data showed four (S1), five (S2) and two (S3) groups of dominant components for the scales of tilapia. It was clearly the formation of disseminated groups in the plot of sheared PCs scores. It is inferred that there was dissimilarity in scale morphological structure of Oreochromis mossambicus collected from different water bodies. [ABSTRACT FROM AUTHOR]

Improving the immune system and growth of fish with seaweed instead of antibiotics can be a good idea for aquaculture. For this purpose, twenty four hundred red tilapia fish after adaptation to laboratory conditions were divided into four treatments with three replicates, and then fed diets contained control (without sargassum extract), 1, 2, and 3% of Sargassum ilisifulium extract for 8 weeks. The results showed that 2% Sargassum extract causes a significant increase in growth indices (specific growth factor, weight gain) and a significant decrease in food conversion ratio (P<0.05). All fish fed with different levels of Sargassum extract had more protein and less fat contents in the body compared to the control group (P<0.05). The amount of total protein, immunoglobulin, and lysozyme activity of the mucus in the fish fed with 2% Sargarsum extract was significantly higher than other experimental groups. (P<0.05). As a result, it is suggested to use 2% of dietary Sargassum extract to improve immunity and growth performance of red tilapia fish. [ABSTRACT FROM AUTHOR]

Chlorella is one of the most widely accepted Chlorophyta used by many as livestock and aquaculture feed. Nonetheless, different studies on the overall performances of fish reported the unfavourable effect of high‐level supplementations of Chlorella vulgaris. The current study determined the impact of low‐level dietary supplementation of C. vulgaris alongside the different feeding durations and their interactions on the growth hormone (GH), growth performances, serum‐biochemical indices, hepatic function and some immunological parameters of red hybrid tilapia. The fingerlings (mean weight: 14.25 ± 0.01 g, length: 13.5 ± 0.49 cm) were fed diets containing 0, 0.99%, 2.91% and 4.76% of C. vulgaris powder per kilogram dry diet for 90 days. GH, growth performance, serum‐biochemical indices (total serum protein, albumin, globulin, glucose, aspartate aminotransferase and alanine aminotransferase) and some immunological (respiratory burst and lysozyme activities) parameters of the fish were examined after 30, 60 and 90 days of feeding. The results demonstrated that tilapia fed C. vulgaris–supplemented diets showed increased levels of respiratory burst, lysozyme, albumin and total protein, GH and growth performances (P < 0.05), and the effects were duration dependent. After the 90 days of feeding, there was no adverse effect on the hepatic function of the fish. Besides, low survivability was observed in the control group than in the group fed the experimental diets. The group fed the diet supplemented with 4.76% C. vulgaris had significantly higher (P < 0.05) lysozyme activity throughout the duration of the feeding experiment. These results indicate that C. vulgaris enhanced growth performances, GH concentration, serum‐biochemistry and some immunological parameters of red hybrid tilapia. [ABSTRACT FROM AUTHOR]

Transglutaminase (TGase) of microbial origin catalyzes the transamide reaction with a glutamine residue in proteins, which correlates with the surimi setting (suwari) process and plays a vital role in manufacturing fish surimi products. This study investigates the effect of TGase-assisted agglutination at different incubation temperatures (20, 30, 40, and 50 °C) in setting the stage to characterize its microstructural influence on agglutination strength and tilapia surimi. Results showed that the preparation of combined heat and TGase treatments significantly increased the hardness, elasticity, gel strength, and water-holding capacity of tilapia surimi gels (P < 0.05). G′ and G″ values were increased, whereas Tan δ was decreased, with significant differences among conditions (P < 0.05). In addition, SDS–polyacrylamide gel electrophoresis showed that myosin heavy chain (MHC) was cross-linked into aggregated macromolecules by TGase. In general, the good performance of tilapia surimi was obtained by heating with minimum addition TGase (0.147 U/g surimi) at 40–50 °C for 1 h. Hence, this study could provide a theoretical basis for developing surimi products with good structure, quality, and high nutritional value. [ABSTRACT FROM AUTHOR]

Streptococcus agalactiae and Streptococcus iniae are the two main pathogens causing streptococcosis in fish. This study compares the clinicopathological changes in red hybrid tilapia experimentally infected with S. agalactiae or S. iniae. A total of 180 tilapias were divided into six groups. Groups 1A, 2A, and 3A were inoculated intraperitoneally with sterile phosphate-buffered saline, S. agalactiae, and S. iniae. Fish of Groups 1A, 2A, and 3A were then immediately allowed to cohabitate with fish of Groups 1B, 2B, and 3B, respectively. All fish were observed at 6-hr intervals for 120 hr before surviving fish were euthanized. The spleen, liver, and brain samples were collected for bacterial isolation and histopathology. Clinical signs were developed at 72 hr in Groups 2A and 3A and 96 hr in Groups 2B and 3B. Group 2A showed the highest clinical score (P<0.05). Significantly (P<0.05), more cohabitating fish (Groups 2B) were infected by S. agalactiae compared to S. iniae (Group 3B) at 55.0±0.0 and 43.70±1.25%, respectively. The mortality rate was significantly (P<0.05) higher for Groups 2A and 2B than other groups. The gross lesions were significantly (P<0.05) more common in fish of Group 2A. Histopathologically, encephalitis was observed in fish infected with S. iniae of Groups 3A and 3B, while meningoencephalitis was observed in fish infected with S. agalactiae of Groups 2A and 2B. The findings suggest that S. agalactiae is more pathogenic than S. iniae, producing slightly different histopathological lesions in the brain. [ABSTRACT FROM AUTHOR]

MYC transcription factors have critical roles in facilitating a variety of cellular functions that have been highly conserved among species during evolution. However, despite circumstantial evidence for an involvement of MYC in animal osmoregulation, mechanistic links between MYC function and osmoregulation are missing. Mozambique tilapia (Oreochromis mossambicus) represents an excellent model system to study these links because it is highly euryhaline and highly tolerant to osmotic (salinity) stress at both the whole organism and cellular levels of biological organization. Here, we utilize an O. mossambicus brain cell line and an optimized vector-based CRISPR/Cas9 system to functionally disrupt MYC in the tilapia genome and to establish causal links between MYC and cell functions, including cellular osmoregulation. A cell isolation and dilution strategy yielded polyclonal myca (a gene encoding MYC) knockout (ko) cell pools with low genetic variability and high gene editing efficiencies (as high as 98.2%). Subsequent isolation and dilution of cells from these pools produced a myca ko cell line harboring a 1-bp deletion that caused a frameshift mutation. This frameshift functionally inactivated the transcriptional regulatory and DNA-binding domains predicted by bioinformatics and structural analyses. Both the polyclonal and monoclonal myca ko cell lines were viable, propagated well in standard medium, and differed from wild-type cells in morphology. As such, they represent a new tool for causally linking myca to cellular osmoregulation and other cell functions. [ABSTRACT FROM AUTHOR]

Curcumin in 0.5% and 1% doses was given as a feed additive to tilapia (Oreochromis mossambicus) for 100 days to evaluate the effect of curcumin on fatty acid levels in brain, appetite and the growth axis‐related gene expressions. A total of 180 fish were randomly stocked into 650 l tanks and fed with basal feed during acclimatization. Three treatment groups were established, each having three replicates and each replicate had 20 fish. They were fed twice on the experimental diets of 10% body weight ration per fish. Gas chromatography analysis revealed a significant change in the amount of total saturated fatty acids and total monounsaturated fatty acids in tilapia brain. The present study indicated an increase in n‐3 (omega‐3) and n‐6 (omega‐6) polyunsaturated fatty acids in brain. Real‐time quantification of appetite‐regulating neuropeptides in brain and growth‐related gene expressions in muscle revealed a significant modulation in their mRNA expressions. This information obtained in the present study on the beneficial role of curcumin in the regulation of fatty acid levels and the expression of appetite‐regulating neuropeptides and growth‐regulating factors will contribute to research in feed intake and growth in fish. [ABSTRACT FROM AUTHOR]

Inland fisheries contribute towards food security for rural communities living close to large aquatic systems. However, sustainable inland fisheries rely on accurate biological information for the target species at the proposed fishery location. In this study, the biological information for Labeo rosae Steindachner, 1894 and Oreochromis mossambicus (Peters, 1852) were determined at Flag Boshielo Dam, Olifants River system, Limpopo province, as part of a larger study to evaluate a small-scale gill net fishery at this impoundment. Nine fish surveys were conducted from February 2016 to April 2017 using mixed sampling gears. Labeo rosae exhibited positive allometric growth (b > 3) while O. mossambicus displayed negative growth (b < 3). For L. rosae, the asymptotic length was 391 mm L∞, and the length-at-50% sexual maturity 165.8 mm. For O. mossambicus, the asymptotic length was 420 mm L∞, and the length-at-50% sexual maturity 166.5 mm. Both species population stocks showed signs of exploitation. Total mortality for L. rosae was 0.57 yr−1 with a fishing exploitation of 0.21 yr−1, while total mortality of 0.78 yr−1 and fishing exploitation of 0.50 yr–1 were estimated for O. mossambicus. The biological data collected, apart from the length–weight parameters for O. mossambicus, are suitable for conducting a fisheries assessment for these species at Flag Boshielo Dam. [ABSTRACT FROM AUTHOR]

The effects of adding a probiotic mixture of Bacillus subtilis and B. licheniformis to an aquaponics system on water quality, fish growth and digestive enzyme activity in Mozambique tilapia, Oreochromis mossambicus, were tested. The fish (36.4 g fish−1 ± 0.10; 3.64 kg m−3 tank volume, 10 fish per tank) were kept in 386-L systems and fed 2% of body mass day−1 for ten weeks. The Bacillus product (Sanolife®PRO-W; 5.0 × 1010 CFU g−1) was added twice weekly. Each treatment was duplicated. The product reduced total dissolved solids and electrical conductivity levels and increased weight gain of Mozambique tilapia. There was no difference between treatment and control in the proximate analysis of the fish. In the Bacillus treatment the activity of the digestive enzymes α-amylase, alkaline protease and alkaline phosphatase was higher than in the control. The probiotic used in this study improved water quality and increased fish growth. [ABSTRACT FROM AUTHOR]

The aquaculture due to the high cost and continued shortage of animal protein sources, the development of alternative plant protein sources has been one of the main challenges to establish sustainable aquaculture as economically viable. Objective of this investigation was to determine the chemical composition and effect of Tithonia diversifolia on the growth performance, feed efficiency and metabolic biochemistry of juveniles of Oreochromis mossambicus × Oreochromis niloticus. Five treatments were used: 0% (control), 4, 8, 12 and 16% levels of inclusion of T. diversifolia flour in diet to feed juvenile fish cultured in 15 plastic aquariums at a density of 15 fish/aquarium. The assay lasted eight weeks. The T. diversifolia flour was characterized for showing adequate levels of crude protein (21%), with low crude fat (4.5%) levels, neutral detergent fiber levels: 43.03% and acid detergent fiber: 24.40%. The growth performance presented significant differences (p=0.05), for weight gain, day average weight gain (DAW), length gain, day average length gain (DAL), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER) and feed conversion ratio (FCR). In treatment with 16% of inclusion of T. diversifolia flour, values obtained for weight gain, DAW, SGR, FE and PER (15.88 g, 0.28 g. day-1, 2.03 %, 0.34 g.g-1 and 0.98, respectively), which did not differ with the control treatment, highlighting the benefits of T diversifolia flour. The metabolic biochemistry parameters experienced a decrease with the increase of T. diversifolia in diet, where the highest values of triglycerides, cholesterol, and glucose were for the control treatment (p <0.05), while the protein increased to 4% of the flour. T. diversifolia flour presents an adequate balance of nutrients for its chemical composition and amino acids, without causing negative effects on the growth performance, weight-length relationship, feed efficiency, survival and metabolic biochemistry. [ABSTRACT FROM AUTHOR]

The current study was conducted during post monsoon season (November, 2021–April, 2022) and 505 tilapia scales were randomly collected from the commercial fish collection centers i.e. Naranpur, Nesu Vadpada and Rumkitalav of Vallabhsagar reservoir, Gujarat, India. Fish scales described the age and growth of tropical conditions that provided detailed facts about their life history, ecology and habitat of fish which help to manage the water body for optimum fish production. The result showed that age of tilapia ranged from 1+ to 5+ year with total length 15.000–33.700±23.598 cm and weight 77.000–662.000±309.951 g. The calculated length (cm) of the back was 8.80, 14.758, 21.612, 26.170 and 28.846 cm while body weight (g) 17.690, 76.171, 223.369, 386.865 and 506.744 g were noted for 5 age classes respectively. The average specific size (5.77) and the index of population weight growth intensity (157.00) were observed whereas specific rate of linear growth (Cl ) and specific rate of weight increase (Cw) were decreasing with increase in age. The growth constant average (Clt(Ave) ) shows two growth phases, i.e. 0.67 and 0.22. The findings of current study help to conclude that the aquatic environment of Vallabhsagar reservoir was suitable to harbour these fishes and was conducive for satisfactory growth and wellbeing of tilapia. Results of the study provided baseline information which would be helpful for the scientific management of Tilapia fisheries in the Vallabhsagar Reservoir in Gujarat. [ABSTRACT FROM AUTHOR]

Age, growth and production performance of O. mossambicus (Peters, 1852) in relation to proliferation of population density in Jaisamand Lake, Udaipur (Rajasthan) has been described and analyzed in the present paper. In this study, the production data for fishing year 1995-96 (February 1995 to March 1996) and 2012-13 (February 2012 to March 2013) are compiled and simultaneously fish morphological data (length and weight) and scale samples are used for age and growth analysis. The findings show that contribution of Tilapia in the total fish production of Jaisamand hiked by 54% to 85% from 1995-96 to 2012-13 which conforms to the predicted invasive effect on other fish fauna and ecosystem of Jaisamand Lake. This increasing trend of Tilapia population is not only affected the indigenous fish population but age and growth structure of Tilapia also has been found affected. Age structure was composed of 3+ year classes during 1995-96. However, due to population density pressure dwarfism was noted and it increased to 4+ year classes. The growth in terms of length and weight also reduced and in AG 1+ 44.21% and 9.09%, in AG 2+ 62.86% and 24.64%, in AG 3+ 72.69% and 38.83% and in pooled population 72.70% and 47.66%, respectively exhibiting a clear decline. On the basis of these findings it can concluded that population increased density and consequent pressure adversely affected indigenous fish fauna resulting into reduced growth rate which directly or indirectly effects livelihood of fisherman and economics of state. [ABSTRACT FROM AUTHOR]

Cortisol is the predominant corticosteroid in ray-finned fish since it does not possess the aldosterone synthase necessary to produce specific mineralocorticoids. Cortisol is traditionally believed to function as a fish mineralocorticoid. However, the effects of cortisol are mediated through corticosteroid receptors in other vertebrates, and there is an ongoing debate about whether cortisol acts through the glucocorticoid receptor (GR) or the mineralocorticoid receptor (MR) in teleosts. To investigate this issue, we conducted a study using euryhaline Mozambique tilapia (Oreochromis mossambicus) as the experimental species. The experiment was designed to investigate the effect of cortisol on ionocyte development at both the cellular and gene expression levels in tilapia. We administered exogenous cortisol and receptor antagonists, used immunohistochemistry to quantify ionocyte numbers, and performed real-time PCR to assess the expression of the differentiation factor tumor protein 63 (P63) mRNA, an epidermal stem cell marker. We observed that cortisol increased the number of Na+-K+-ATPase (NKA)-immunoactive ionocytes (increased by 1.6-fold) and promoted the gene expression of P63 mRNA (increased by 1.4-fold). Furthermore, we found that the addition of the mineralocorticoid receptor antagonist Spironolactone inhibited the increase in the number of ionocytes (decreased to the level of the control group) and suppressed the gene expression of P63 (similarly decreased to the level of the control group). We also provided evidence for gr, mr, and p63 localization in epidermal cells. At the transcript level, mr mRNA is ubiquitously expressed in gill sections and present in epidermal stem cells (cells labeled with p63), supporting the antagonism and functional assay results in larvae. Our results confirmed that cortisol stimulates ionocyte differentiation in tilapia through the MR, rather than the GR. Therefore, we provide a new direction for investigating the dual action of osmotic regulation and skin/gill epithelial development in tilapia, which could help resolve previously inconsistent and conflicting findings. [ABSTRACT FROM AUTHOR]

Background: Triclosan is an antimicrobial agent which enters into the aquatic environment through wastewater discharges which causes potential health risk in human and aquatic organisms. The present study aimed to determine the toxic effects of triclosan on Oreochromis mossambicus. Methods: The fishes were subjected to five different concentrations viz. 131, 262, 523, 1046 and 2092 µg.l-1 of triclosan for 96 h acute toxicity test. To evaluate the levels of enzymes such as acetylcholinesterase and glutathione S transferase, brain and liver tissues were collected, homogenized, extracted and stored at -20°C for further analysis. The DNA damage was assessed in gill and liver tissues using single cell gel electrophoresis method. Result: In present study, the calculated 96 h LC50 value of triclosan in O. mossambicus was 740 µg.l-1 and the fishes showed various behavioural alterations. Time and dose dependent inhibition of AChE activity in brain tissue was observed during acute toxicity test. However, the GST activity in liver tissue increased on exposure to triclosan with significant increase in concentration of toxicant. DNA damage index was higher in gill tissue compared to the liver tissue during acute exposure to TCS which could cause detrimental effects in fishes. [ABSTRACT FROM AUTHOR]

Background and Objectives: Skin scaffolding can be done using allografts and autografts. As a biological allograft, the skin of Oreochromis niloticus (ON) has been used due to its high type I and III collagen content. Oreochromis mossambicus (OM) is also a member of the Oreochromis family, but not much is known regarding its collagen content. As such, this study aimed to assess and compare the collagen content of the two fish species. Materials and Methods: This is a crossover study comparing the skin collagen contents of the two fish. Young fish were chosen, as they tend to have higher collagen concentrations. The skin samples were sterilized in chlorhexidine and increasing glycerol solutions and analyzed histochemically with Sirius red picrate under polarized light microscopy. Results: 6 young ON and 4 OM specimens were used. Baseline type I collagen was higher for OM, but at maximum sterilization it was higher for ON, with no differences in between Type III collagen was higher for OM across all comparisons with the exception of the last stage of sterilization. Generally, collagen concentrations were higher in highly sterilized samples. Conclusions: OM skin harvested from young fish, with its greater collagen III content may be a better candidate for use as a biological skin scaffold in the treatment of burn wounds, compared to ON. [ABSTRACT FROM AUTHOR]

Mozambique tilapia Oreochromis mossambicus (Peters, 1852), an important aquaculture species investigated herein, is at risk and listed as vulnerable on the IUCN Red List. During a preliminary survey conducted in 2011, 30 Mozambique tilapia from Lake Urema in Gorongosa National Park in central Mozambique, were examined for metazoan parasites. Two groups of ectoparasites were recovered consisting of two species of copepods and a monogenean. Endoparasites retrieved were in the larval stage and included one trematode and one nematode species. This study provides new parasite records for O. mossambicus in Mozambique and forms a baseline for monitoring against the presence of ichthyoparasites associated with the introduction in neighbouring systems of non-native fish such as Nile tilapia Oreochromis niloticus (Linnaeus, 1758), a fish of worldwide importance in capture fisheries and especially aquaculture. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of cortisol on the regulation of the glycogen metabolism biomarkers glycogen synthase (GS) and glycogen phosphorylase (GP) in the glycogen-rich cells of the gills of tilapia (Oreochromis mossambicus). In the gills of tilapia, GP, GS, and glycogen were immunocytochemically colocalized in a specific group of glycogen-rich cells adjacent to the gills' main ionocytes and mitochondria-rich cells. Cortisol plays a vital role in the regulation of physiological functions in animals, including energy metabolism, respiration, immune response, and ion regulation. However, no studies have elucidated the mechanisms regulating cortisol and glycogen-rich cells in the gills. Therefore, we treated tilapia larvae with exogenous cortisol and a glucocorticoid receptor (GR) antagonist to investigate the regulatory mechanisms between cortisol and glycogen-rich cells in the gills. Our results showed that cortisol promoted the expression of gill glycogen phosphorylase isoform (GPGG) mRNA via GR, whereas the GS gene expression remained unaffected. We also found that GR mRNA was colocalized with some glycogen-rich cells in the gills, further confirming our hypothesis that cortisol directly acts on glycogen-rich cells in the gills of tilapia and regulates glycogen metabolism by promoting GPGG mRNA expression. [ABSTRACT FROM AUTHOR]

In this study, umami-rich seasoning powder was produced from the offcuts of Taiwanese tilapia (Oreochromis mossambicus) by cooking concentration and spray drying of granules while yielding an abundance of glutamic acid (0.23 mg/100 g), glycine (0.10 mg/100 g), aspartic acid (0.11 mg/100 g), lysine (0.10 mg/100 g), and 11 other aminic acids. It exhibited water content (3.81%), water activity (0.3), powder yields (68.83%), and a good water solubility index (99.89%), while the particle microstructure was a spherical powder. Additionally, it received the highest overall preference score (7.53) in the consumer-type sensory evaluation compared to commercially available seasonings. This study proves that offcuts may be part of the human diet after proper processing and can be widely used to flavor savory food. The producers involved could increase their economic returns while meeting the environmental challenges. The practical contribution could create incremental value for products to critical stakeholders at each point in the tilapia supply chain with an operational guide for transitioning from inefficient to innovative circular practices. [ABSTRACT FROM AUTHOR]