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Ikan pekasam is an example of traditional fermented food products in Malaysia, prepared from freshwater fish such as black tilapia (Oreochromis mossambicus) and Javanese carp (Puntius gonionotus), salt and ground roasted rice, which is added as the only source of carbohydrate. However, some producers add tamarind (Tamarindus indica) pulp and/or dried slices of Garcinia atroviridis to assist the fermentation process. In this study, there was no correlation detected between pH value, titratable acidity (% lactic acid), salt concentration, organic acid composition and the consumer acceptability of ikan pekasam commercial samples made of black tilapia as well as Javanese carp. The organic acid composition in both natural and acid-assisted fermented ikan pekasam from black tilapia and Javanese carp were compared. The results obtained showed that lactic acid was the major organic acid detected, followed by succinic acid and acetic acid. The addition of tartaric and/or garcinia acids was proven to reduce the fermentation time. Therefore, the addition of acid has assisted the fermentation process by increasing the total organic acid content, mainly lactic acid. Moreover, the 9-point hedonic scale showed that ikan pekasam made of Javanese carp had higher overall acceptability due to tender flesh/muscle texture compared to black tilapia regardless of the fermentation process and organic acid content

Aquaculture in Mozambique was introduced in the late 1950s, and several strategies have since been put in place to develop the sector, especially in growing the Mozambique Tilapia (Oreochromis mossambicus). The study assessed aquaculture production in the Gaza Province of Mozambique. Data was obtained from semi-structured interviews and questionnaires in companies, community associations, and individuals focusing mainly on their adopted production systems, challenges, and opportunities. The study identified 15 fish farmers, with a total of 301 fish culture facilities in which 86% were ponds and 14% cages with cultivation structure varying from 120 m2 to 2000 m2 for ponds and 6 m3 to 13 m3 for cages. Two production systems were distinguished including extensive and semi-intensive with 61% and 39% respectively. Oreochromis niloticus was the main cultured species. These farmers get their feed from Livestock Feed Limited (LFL) and AquaPlus. The unavailability of quality feed, seed and inadequate extension workers were listed as the main challenges faced by the farmers leading to low fish production. Our findings clearly show that fish farming is an attractive activity for small and medium-scale farmers, and it can grow especially if necessary measures are taken to improve management, access to inputs, and extension services.

Copper (Cu) is a heavy metal that is absorbed by organisms, such as Oreochromis mossambicus fish. This research aims to measure the bio-concentration of Cu in Oreochromis mossambicus and to predict the daily consumption of the fish. Samples of Oreochromis mossambicus fish were obtained from fishermen and collectors. The Cu concentration in the water and 30 fish was identified using the Atomic Absorption Spectrophotometry method. Questionnaires were employed to identify the demographic data of 101 respondents. The average concentration of Cu in the Oreochromis mossambicus fish and Rawapening Lake's water was 0.063 mg/l and 0.6 mg/kg, respectively. Furthermore, the bio-concentration of Cu in the Oreochromis mossambicus fish was 10.26±5.17 and categorized as low, while the average daily consumption of fish was 225±36.89 g/day. Therefore, it was concluded that the average bio-concentration and the daily consumption of the fish are in the low and safe category respectively.

Fish is a rich source of proteins for humans and is widely consumed in various places in the world. This study assessed the levels of twenty trace metals (B, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Sb, Ba, Hg and Pb) in fish feeds (n = 2), water (n = 27), and edible muscles of Oreochromis mossambicus (n = 20 from 8 ponds) from fish farms and Luvuvhu River (n = 3 from 1 river site) in Vhembe district of Limpopo Province, South Africa. Physicochemical parameters of water in the study area were analysed. Temperature ranged between 21.4–30.47 °C, pH: 5.59–7.28, electrical conductivity: 608–1216 μS/cm, total dissolved solids: 156–675 mg/l, dissolved oxygen: 0.28 - 0.56 mg/l, turbidity: 3.92–356.7 NTU, respectively. Levels of most trace metals such as Cr (2 μg/l and 1000 μg/kg), Mn (100 μg/l and 500 μg/kg), Fe (10 μg/l and 300 μg/kg), Ni (20 μg/l and 100 μg/kg), As (50 μg/l and 3 μg/kg), Pb (10 μg/l and 300 μg/kg) and Cu (2 μg/l and 2250 μg/kg) in water and O. mossambicus muscles were mostly below the World Health Organization (WHO), Food and Agricultural Organization (FAO)/WHO and European Commission (EC) recommended limit in the collected samples (Tshifulalani site and Duthuni site). However, Cu and Fe recorded concentration above the recommended limit at the control site (Luvuvhu River) in water and O. mossambicus muscles, respectively. Results from the bioaccumulation factor (BF), suggests the presence of metals in the water which can bioaccumulate in the fish muscles. Most of the metals (As, Cd, Hg, Mo, Sr, Sb and Sn) that recorded no possible bioaccumulation also recorded levels that complied with their maximum permissible limit (MPL) of WHO, FAO/WHO and EC guideline values in the fish feeds except for Se and Co. Moderate bioaccumulation was recorded for Cr, Mn, Fe and Zn in some of the sampling sites. Pb and Ni showed extreme bioaccumulation (BF > 5000) in one of the sampling sites and also recorded elevated levels in the fish feeds. Average daily dose (ADD), hazard quotient (HQ) and total hazard quotient (THQ) computed were less than 1. The Cancer risk (CR) evaluated were all below 10−4 except in one site for children (Tshifulanani 2) but the overall average result showed no carcinogenic health risk to the consumers of the O. mossambicus. Therefore, O. mossambicus intake in the study area should be constantly monitored to prevent future health implications.

Tilapia fish (Oreochromis mossambicus) is a type of freshwater consumption fish, flat body shape with grey, brown or black colour. The purpose of this study was to describe the types of food found in the stomach of tilapia fish (Oreochromis mossambicus) in Talaga Lake, Donggala Regency. This research was conducted in April 2019. The method used in this study was a volumetric occurrence frequency method by a surgical sampling of fish to extract the stomach and analyze it. Based on the results of the analysis of the stomach contents of the Mujair fish (Oreochromis mossambicus), two groups of feed were obtained, namely Vegetable food (Fitoplaknton) in the form of Navicula placentula, Schroederia segitera, Schoroederia anchora, Zignemopsis circumcaniratum, Anabaena sp, Oscillatoria princeps, Spirogyra protifica, Bacillaria sp, Nitzschia aetinastroides, Oedogonium sp, Coelastrum chodati, and animal feed (Zooplankton) in the form of Tubipex sp, Brachionus havanaensis, Cyclops sp, Carcinus sp, Arcella sp, Acetes sp.

The Australian red-claw crayfish, Cherax quadricarinatus, has been introduced for aquaculture purposes worldwide and consequently colonized natural environments, where it might cause ecosystem services losses or adversely affect native species and the local environment. This species was first found in Pequenos Libombos Reservoir in Maputo Province, Southern Mozambique in the late 2009 and is linked to reduction in tilapia fisheries. This study, conducted in 2015 under controlled conditions, aimed to assess the interspecific relationships between the Mozambique tilapia (Oreochromis mossambicus) and the alien crayfish. For both species, no significant differences in growth and survival rates were found between animals reared in the presence versus the absence of heterospecifics, indicating no direct deleterious interspecific effects. Behavioural observations revealed that fish and crayfish competed for shelter and food. Both species reduced the foraging in the presence of heterospecifics during feeding period, in the daytime. Crayfish seemed to have an advantage in competition for shelter, suggesting that they may interfere with tilapia sheltering activity and make tilapia vulnerable to predators in natural habitats. Resumo O lagostim australiano, Cherax quadricarinatus, tem sido introduzido para fins de aquicultura em todo o mundo e, consequentemente, colonizado ambientes naturais, onde pode coexistir com a biota local sem causar perdas nos serviços dos ecossistemas ou afetar negativamente as espécies nativas e o meio ambiente local. Esta espécie foi encontrada pela primeira vez na Albufeira dos Pequenos Libombos, na Província de Maputo, sul de Moçambique, no final de 2009 e foi relacionada à redução da pesca de tilápias registrada na mesma localidade. Este estudo, conduzido em 2015 sob condições controladas, teve como objetivo avaliar as relações interespecíficas entre a tilápia de Moçambique (Oreochromis mossambicus) e o lagostim invasor (C. quadricarinatus). Para ambas espécies, não foram encontradas diferenças significativas nas taxas de crescimento e sobrevivência entre animais criados na presença versus ausência de heteroespecíficos, indicando ausência de efeitos deletérios interespecíficos diretos. Observações comportamentais revelaram que peixes e lagostins competiam por abrigo e comida. Ambas espécies reduziram o forrageamento na presença de heteroespecíficos durante o período de alimentação, no período diurno. O lagostim parece ter uma vantagem na competição por abrigos, sugerindo que, em habitats naturais eles podem provocar o deslocamento de tilápias de seus abrigos, e deste modo tornar as tilápias vulneráveis aos predadores.

Histopathological manifestation of castor bean seed as fish toxicant upon gastro-intestinal system of Tilapia (Oreochromis mossambicus) was investigated parallel with mohua oil cake as haemotoxic piscicidal agent in outdoor experimental tanks. Castor seed bean was proved to be an effective piscicide with activity potential comparative with mohua oil cake though the mortality rate was higher and quicker in the later. As plant derived toxicant castor bean exhibited strong histopathological lessions in intestinal mucosa and liver whereas, mohua oil cake exhibited severe respiratory distress to the test fish. Significant reduction of dissolved oxygen and concurrent increase in BOD1 of water under both the piscicides aggravated the distress of the test fish.

Background and Aim: Aeromonas hydrophila is a major cause of bacterial infections affecting a wide range of warm water fishes worldwide. In Malaysia, A. hydrophila isolations from diseased fishes were previously reported; however, with limited information. The present study investigates the antibiotic susceptibility and pathogenicity of A. hydrophila isolated from farmed red hybrid tilapia (Oreochromis spp.) in Malaysia. Materials and Methods: A. hydrophila was biochemically identified and subjected to antibiotic susceptibility tests. The isolate was then intraperitoneally injected into red hybrid tilapia, and the mortality, clinicopathological changes, and LD50 were determined up to 240 h post-infection (hpi). Results: The isolate demonstrated multiple antibiotic resistances (MAR) toward amikacin, ampicillin, cefotaxime, amoxicillin, trimethoprim-sulfamethoxazole, erythromycin, and streptomycin, with a MAR index of 0.5. The experimental infection of A. hydrophila at 105 CFU/mL in the red hybrid tilapia resulted in 100% mortality at 240 hpi. The LD50 was determined at 1.1×104 CFU/mL. Infected fish demonstrated occasional erratic swimming patterns, localized hemorrhages and depigmentation on the body and operculum areas, fin erosion, enlargement of the gall bladder, and hemorrhage in internal organs. Microscopic observation of infected fish revealed brain congestion, tubular necrosis, and glomerular shrinkage in the kidneys, necrosis of hepatocytes, and congestion of blood vessels in the liver. Conclusion: The high virulence of A. hydrophila to the red hybrid tilapia emphasizes the importance of active, on-going monitoring of its prevalence in Malaysian tilapia farming.

Pansteatitis is the leading cause for the decline in Nile crocodile populations and the sporadic mortality of fish in the Olifants River System, South Africa. To determine the prevalence of this disease in lentic systems, Mozambique tilapia, Oreochromis mossambicus, were collected from Lake Loskop, Lake Flag Boshielo, Phalaborwa Barrage and Lake Luphephe-Nwanedi. The former three impoundments are located within the main stem of the Olifants River, while the latter, which is geographically isolated and situated in the Limpopo River System, served as a reference site. Mesenteric adipose, liver, serosa of the swim bladder, gill and the skeletal muscle of fish sampled were examined for gross and microscopic evidence of pansteatitis. Microscopically observed changes were used to statistically compare pansteatitis prevalence between samples and sites. Based on histopathological evaluation, the adipose tissue in the liver, swim bladder serosa and coelom from severely debilitated individuals showed the most significant pathological changes. Lesions indicative of steatitis were observed in fish collected from Lake Loskop (75%), Lake Flag Boshielo (22%) and Lake Luphephe-Nwanedi (15%). Further investigation is warranted to understand the pervasiveness and mechanisms driving pathological changes of pansteatitis at Lake Flag Boshielo, Phalaborwa Barrage and Lake Luphephe-Nwanedi.

The field of nanotechnology is rapidly expanding with the advancement of novel nanopesticide and nanofertilizers that have the potential for revolutionizing applications in the agricultural industry. Here, we have done chronic toxicity of cadmium dioxide nanoparticles (CdONPs) on fishOreochromis mossambicus(O. mossambicus) using oxidative stress and genotoxic biomarkers. In this current study, the value of LC50-96 hr of CdONPs has observed 40 μg/ml forO. mossambicus.The three sublethal concentrations, e.g., 4, 10, and 20 μg/ml were selected based on the LC50value. The fishes were treated to the above concentration of CdONPs for 21 days and were harvested at 1, 7, 14, and 21 days for evaluation of clastogenicity, mutagenicity, and genotoxicity of NPs. Generally, significant effects (p<0.01) were observed as a dose and duration of exposure. It was observed that lipid peroxidation (LPO) was increased and glutathione was decreased in both tissues. Micronuclei (MNi) were produced significantly in peripheral blood on 21 days at maximum concentration. A similar trend was seen in the damage of DNA with the same manner in terms of the percentage of tail DNA in the lymphocyte, gills, and kidney cells. This study explored the application oxidative stress, comet assay, and micronucleus assay for in situ aquatic laboratory studies using fishO. mossambicusfor screening the ecomutagenic and genotoxic potential of environmental pollutants.

The far reaching dissemination and toxic nature of pesticides and their elements seriously affects the aquatic surroundings, and exerts negative consequences on the related organisms. The present study was carried out to investigate the effect of malathion and neem oil individually and also in combination on the fresh water fish, Oreochromis mossambicus to elucidate the change in the different target organs like liver and kidney with reference to biochemical and histopathological studies. Median lethal concentration (LC50) of neem oil and malathion was maintained for acute toxicity (96 hours) and chronic toxicity (21 days) studies. Further the fishes were segregated into 4 groups where in each group contained 6 fishes. Group I fishes were maintained in tap water, Group II in neem oil, Group III fishes were maintained in malathion , Group IV fishes were maintained in both neem oil and malathion. The LC50 dose of neem oil and malathion was found to be 0.9 ml/L and 3.52 mg/L respectively. The results of biochemical analysis revealed that total protein and lipid increased in combination of neem oil and malathion which was comparatively more than that of the neem oil and malathion maintained individually. The total free sugar showed a decrease in combination as well as individually in acute toxicity study .However there is an increase in total free sugar as observed in chronic toxicity study. Histopathological study in acute and chronic toxicity (i) in liver, fishes exposed to neem oil showed normal hepatocellular architecture while fishes exposed to malathion only and those of malathion combined with neem oil showed hepatocellular degeneration while the latter showed the signs of recovery (ii) in kidney the neem oil exposed fishes showed normal renal architecture , malathion exposed fishes showed epithelial cell degeneration and necrosis, while those exposed to neem oil and malathion combined showed mild degeneration. This study indicated the action of neem oil which has interacted with malathion and reveals a protective influence on harmful effects of the toxicant.

Although photoperiod plays a critical role in seasonally breeding fish, effect of altered photoperiod on reproduction of continuously breeding fish is not well understood. The objective of this investigation is to determine the effect of continuous light exposure on testicular activity in Oreochromis mossambicus. The fish were exposed to simulated photoperiod and continuous light for 21 days. Although the mean numbers of spermatogonia and primary spermatocytes did not show significant difference, the mean numbers of secondary spermatocytes, early spermatids and late spermatids were significantly lower in fish exposed to continuous light compared to those of initial controls (fish euthanized on the day of commencement of experiment), controls (fish kept in natural photoperiod) and fish exposed to simulated photoperiod. Furthermore, diminished immunoreactivity of androgen receptors was observed in the Sertoli cells concomitant with significantly lower serum levels of testosterone in fish exposed to continuous light compared to other experimental groups. In addition, the mean serum cortisol levels were significantly higher in continuous light fish group compared to other experimental groups. Overall, these results indicate that exposure to continuous light inhibits advanced stages of spermatogenesis, possibly through the suppression of testicular steroidogenesis and that this effect might be mediated through the stress-axis in O. mossambicus.

Euryhaline tilapia (Oreochromis mossambicus) are fish that tolerate a wide salinity range from fresh water to > 3× seawater. Even though the physiological effector mechanisms of osmoregulation that maintain plasma homeostasis in fresh water and seawater fish are well known, the corresponding molecular mechanisms that control switching between hyper- (fresh water) and hypo-osmoregulation (seawater) remain mostly elusive. In this study we show that hyperosmotic induction of glutamine synthetase represents a prominent part of this switch. Proteomics analysis of the O. mossambicus OmB cell line revealed that glutamine synthetase is transcriptionally regulated by hyperosmolality. Therefore, the 5′ regulatory sequence of O. mossambicus glutamine synthetase was investigated. Using an enhancer trapping assay, we discovered a novel osmosensitive mechanism by which intron 1 positively mediates glutamine synthetase transcription. Intron 1 includes a single, functional copy of an osmoresponsive element, osmolality/salinity-responsive enhancer 1 (OSRE1). Unlike for conventional enhancers, the hyperosmotic induction of glutamine synthetase by intron 1 is position dependent. But irrespective of intron 1 position, OSRE1 deletion from intron 1 abolishes hyperosmotic enhancer activity. These findings indicate that proper intron 1 positioning and the presence of an OSRE1 in intron 1 are required for precise enhancement of hyperosmotic glutamine synthetase expression.

This study aims to determine the pattern of breeding, adaptability to the environment and feeding processes in tilapia fish Oreochromis mossambicus through morphological data, morphological data obtained through morphometric measurements that can be used to formulate the extent of the threat to local species because tilapia is an invasive fish species with morphological data. Fairly high reproduction in freshwater waters. The location of this research is swamp waters in Manokwari Regency, namely Prafi, Masni and Sidey Regions. Morphometric measurements using 14 standards. Morphometric measurement results of male fish showed that the width of the tail fin (CFW) there was a significant difference in the width of the tail fin (CFL) between the tilapia fish in the Prafi swamp with the other two marshes, the width of the tilapia fish tail fins in the Masni and Sidey swamps did not differ significantly. In female fish measurements (DFL) showed that there were significant differences while the CFW measurements contained in the Prafi swamp were different from the other two marshes. The results of the morphometric measurements show how the morphological characteristics of tilapia fish will have an impact on local fish and the amount of natural food in the Swamp.

Background: Snakes feed on germ-infested rodents, while water monitor lizards thrive on rotten matter in unhygienic conditions. We hypothesize that such creatures survive the assault of superbugs and are able to fend off disease by producing antimicrobial substances. In this study, we investigated the potential antibacterial activity of sera/lysates of animals living in polluted environments. Methods: Snake (Reticulatus malayanus), rats (Rattus rattus), water monitor lizard (Varanus salvator), frog (Lithobates catesbeianus), fish (Oreochromis mossambicus), chicken (Gallus gallus domesticus), and pigeon (Columba livia) were dissected and their organ lysates/sera were collected. Crude extracts were tested for bactericidal effects against neuropathogenic E. coli K1, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Pseudomonas aeruginosa, Bacillus cereus and Klebsiella pneumoniae. To determine whether lysates/sera protect human cells against bacterialmediated damage, cytotoxicity assays were performed by measuring lactate dehydrogenase release as an indicator of cell death. Lysates/sera were partially characterized using heat-treatment and pronasetreatment and peptide sequences were determined using the Liquid Chromatography Mass Spectrometry (LC-MS). Results: Snake and water monitor lizard sera exhibited potent broad-spectrum bactericidal effects against all bacteria tested. Heat inactivation and pronase-treatment inhibited bactericidal effects indicating that activity is heat-labile and pronase-sensitive suggesting that active molecules are proteinaceous in nature. LCMS analyses revealed the molecular identities of peptides. Conclusion: The results revealed that python that feeds on germ-infested rodents and water monitor lizards that feed on rotten organic waste possess antibacterial activity in a heat-sensitive manner and several peptides were identified. We hope that the discovery of antibacterial activity in the sera of animals living in polluted environments will stimulate research in finding antibacterial agents from unusual sources as this has the potential for the development of novel strategies in the control of infectious diseases.

The heavy metal contamination is creating devastating effects on ecosystem and environment and eventually hazardous to human health. Ujjani is one of the largest reservoir in Maharashtra state. It receives water from different metropolitan cities harboring numerous industries. Moreover, anthropogenic activities pollute water and fish fauna of the reservoir. In the present study, the concentrations of heavy metals such as Iron (Fe), Copper (Cu), Zinc (Zn), and Manganese (Mn) were analyzed from various tissues namely muscles, liver, gill, and fin of Chillapi fish. The variation in level of metals was found with respect to tissue types and body weight groups. The concentrations of Fe were ranged between 15.94 to 91.56µg/g, Cu concentration was between 1.88 to 48.88µg/g, Zn concentration was between 25.72 to 84.2µg/g and Mn was recorded between 2.12 to 28.48µg/g in Chillapi fish. Fe and Cu have recorded highest in the liver, whereas peak of Zn and Mn was detected in fins. Furthermore, the minimal metal concentrations were observed in muscle samples of all different weight groups. It shows that Fe, Zn, Cu concentration in all four tissues was within the limit, whereas the Mn level was found to be exceeding the permissible limit as prescribed FAO/WHO, 1989. The presence of heavy metals higher than normal level in fish bodies is a clear indicator of biomagnifications. Furthermore, THQ and HI values were within limit for all studied metals in fish but if consumed in excess amount may cause toxicity in humans. Therefore, daily intake of fish should be strictly monitored to avoid excess intake of these heavy metals. Our study signifies the importance of addressing the heavy metal contamination issue to avoid health related problems.

It has been hypothesized that androgens respond to the social interactions as a way to adjust the behavior of individuals to the challenges of the social environment in an adaptive manner. Therefore, it is expected that transient changes in circulating androgen levels within physiological scope should impact the state of the brain network that regulates social behavior, which should translate into adaptive behavioral changes. Here, we examined the effect that a transient peak in androgen circulating levels, which mimics socially driven changes in androgen levels, has on the forebrain state, which harbors most nuclei of the social decision-making network. For this purpose, we successfully induced transient changes in circulating androgen levels in an African cichlid fish (Mozambique tilapia, Oreochromis mossambicus) commonly used as a model in behavioral neuroendocrinology by injecting 11-ketotestosterone or testosterone, and compared the forebrain transcriptome of these individuals to control fish injected with vehicle. Forebrain samples were collected 30 min and 60 min after injection and analyzed using RNAseq. Our results showed that a transient peak in 11-ketotestosterone drives more accentuated changes in forebrain transcriptome than testosterone, and that transcriptomic impact was greater at the 30 min than at the 60 min post-androgen administration. Several genes involved in the regulation of translation, steroid metabolism, ion channel membrane receptors, and genes involved in epigenetic mechanisms were differentially expressed after 11-ketotestosterone or testosterone injection. In summary, this study identified specific candidate genes that may regulate socially driven changes in behavioral flexibility mediated by androgens. Fundação para a Ciência e Tecnologia - FCT info:eu-repo/semantics/publishedVersion

In the present investigation, we evaluated if the presence of tilapia affects growth and survival of shrimp during pre-growth and grow-out phases. In both experiments, we used a random-blocks design in a single earth pond (0.75 ha) that was prepared and divided into nine (7 x 30 m) enclosures that were considered to be three blocks of three enclosures each. Each randomly stocked block consisted on Pacific white shrimp Litopenaeus vannamei (30 shrimp/m2) and three different densities (0.0, 0.25 and 0.50 fish/m2) of red tilapia hybrids (Oreochromis mossambicus x Oreochromis niloticus) to give three different treatments with three replicates. The results from the pre-growth and grow-out experiments followed the same trend. In both cases, we found no significant statistical differences (P>0.05) in the final average weight of the shrimp. However, the experimental blocks had a significant (P

Tilapia fish waste and livestock manure are an environmental problem, besides being smelly pollution will also cause disease disorders for humans. The purpose of this study was to determine the levels of micronutrients of iron (Fe) and copper (Cu) on pellets from the fermentation of waste tilapia (oreochromis mossambicus) using adhesive goat manure. Fish waste was fermented for 15 days and mixed with adhesive goat manure and then was processed in a pellet making machine. The Fe and Cu levels were determined using Atomic Absorption Spectrophotometer (AAS). The results of the determination of levels Fe was 137 ppm and for Cu was 4.1 ppm.

Tilapia is a popular fish for consumers and aquaculture in every part of Thailand. This study was conducted to determine the level of mineral supplementation in the diet for the growth of red tilapia fingerlings, which gave the lower fish production cost. The fingerlings with an initial average weight of 3.1 ± 0.48 g and a length of 2.5±0.24 cm were raised in 3 m3 concrete tank with 1.5 m3 of water volume at 20 fish/m2 stocking density. Fish were fed with pellets diet (28 % crude protein), which contained different levels of mineral supplements (0 (control), 20 and 40 g/Kg) in triplicate replications. The experiment was conducted within 80 days. The results showed that fish fed with diet3 had better average daily weight gain (ADG) and food conversion ratio (FCR) than diet2 and diet1 significantly (P0.05), and the fish production cost of diet 3 is lower than those in diet1 and diet2. Thus, this experiment concluded that minerals supplementation at the level 40 g/kg diet were suitable for tilapia aquaculture.

The opioid peptides are involved in the regulation of neuroendocrine functions in vertebrates. Nonetheless, the influence of an opioid peptide, dynorphin A (DYN), on reproduction in fish is understudied. The aim of this work was to study the influence of DYN on the pituitary-ovary axis in Oreochromis mossambicus. Daily injections (ip) of 250 μg DYN kg-1 body weight for 22 days during the ovarian cycle caused a reduction in the intensity and the per cent area of luteinizing hormone (LH) immunoreactive content in the proximal pars distalis region of the pituitary gland compared with an intense immunostaining in time-matched controls. In the ovary, DYN treatment caused a decrease in the number of stage I (previtellogenic) follicles compared with time-matched controls. No difference was observed in the number of stage IV (vitellogenic) follicles among different experimental groups, whereas the numbers of stage II and stage III follicles (previtellogenic) were higher in DYN-treated fish than in time-matched controls. Nonetheless, there was a reduction in the number of stage V (preovulatory) follicles in DYN-treated fish compared with time-matched controls. Taken together, these results indicate that DYN exerts an inhibitory effect on follicular recruitment at the late vitellogenic stage, through the suppression of LH secretion in fish.

In the current study heavy metal removing capability and antioxidant properties of chitosan supplemented diet tested in lead poisoning induced Oreochromis mossambicus in comparison with and standard fish diet. O. mossambicus fishes weighed (20 ± 2gm) were purchased from a local commercial fish pond and acclimated to the laboratory conditions for 10 days. After that fish were dived into four groups, each group received respective feed throughout the experimental period. The fish fed with standard diet exhibited drastic weakening of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GR), glutathione peroxidase (GPx), ascorbic acid, α- tocopherol and β-carotene and also displayed abnormal histological changes in gills, liver, and intestine. The fish fed with a chitosan supplemented diet for 10 days showed substantial enhancements in antioxidant levels and also normal histological structures of organs in the fish.

An experiment was conducted to replace soya bean meal (SBM) with cashew nut meal (CNM) in the diet of tilapia (Oreochromis mossambicus). Five isonitrogenous (30% CP) and isolipidic (6% CL) diets, CNM0 to CNM4, were prepared replacing SBM at 0%, 12.5%, 25%, 37.5% and 50% with CNM. The feeding trial was conducted in FRP digestibility tanks of 150 L capacity for 60 days. Twenty tilapia fry (20.56 ± 0.05 g) were stocked in each tank. The final weight, weight gain and weight gain% of tilapia that received the CNM4 diet were significantly higher (p .05) among the treatments. It can be concluded from the study that 50% replacement of SBM with CNM in the diet is suitable for the enhancement of growth, nutrient utilization and health status of tilapia.

Cadmium (Cd), a heavy metal, is widely used in modern industries including in metal and mining industries as well as in the manufacture of Ni Cd batteries. Its bioaccumulation is reported to induce hazardous effects in aquatic organisms including fish. Hence, the present study was undertaken to evaluate the toxic potential of cadmium in Tilapia (Oreochromis mossambicus Peters). Fish were exposed to 3 sub-lethal concentrations of CdCl2: 7.4 μg/l (high), 3.7 μg/l (medium) and 1.85 μg/l (low) for a period of 21 days. Ten fish were used for each group and each exposure was done in triplicates. A group of 10 fish without exposure to CdCl2 was used as control. Genotoxic effects of Cd were assessed employing micronucleus assay and the comet assay. Along with these tests, alterations in the amount of the enzymes acetylcholine esterase (AChE) and catalase (CAT), as well as, the quantum of Cd accumulated in different tissues of the organism were also studied. A significant increase in DNA damage as % tail DNA and micronuclei were observed in the fish exposed to CdCl2. CdCl2 also induced a significant increase in the activity of CAT whereas a decrease in the activity of AChE was observed. A significant association was also observed between DNA damage parameters and catalase activity as well as Cd concentration in the gills. Cd may thus induce genotoxicity in O. mossambicus via oxidative stress and tissue accumulation. The combined use of these biomarkers in O. mossambicus could be used to monitor Cd contamination in the aquatic environment.