Aquaculture is currently playing, and will continue to play, a big part in boosting global fish production and in meeting the rising demand of fishery products. Capture fisheries production has levelled off and is no longer considered capable of sustaining the supply of fisheries products needed to meet the growing global demand. Tilapia is the common name for several species of cichlid fish inhabiting freshwater streams, ponds, rivers and lakes and less commonly in brackish water. Considered as an invasive species, tilapias are now of increasing importance in Aquaculture. Tilapia is the second most farmed fish world-wide and its production has quadrupled over the past decade because of its suitability for aquaculture, marketability and stable market prices. Native to Africa and Middle East, tilapias were introduced into over 90 countries for aquaculture and fisheries. Tilapia continued its rapid increase in global production. Recent production figures reported by various sources, our global production estimate for 2015 is 5,576,800 mt.  Tilapias are now one of the most widely introduced fish globally that has clearly emerged as a very promising group in aquaculture.

A 60 days indoor growth trial was conducted to study the effect of dietary supplementation of biofloc meal on growth and survival of juvenile GIFT tilapia. Four isonitrogenous and isoenergetic experimental diets (32% crude protein) were prepared using biofloc meal at different inclusion levels viz., 0 (T0), 20 (T1), 30 (T2) and 40% (T3). A commercial diet (T4) was used for comparison. The feeding trial was conducted in 15 nos. of 40 l plastic troughs in triplicate, utilising GIFT tilapias weighing an average of 2 g. During the experimental period, water quality parameters were measured and recorded daily. The mean value of water temperature, pH, dissolved oxygen, salinity, ammonia-N, nitrite-N, nitrate-N, hardness and alkalinity recorded in the experimental systems were 28.5°C, 8.1, 5.5 ppm, 4.5 ppt, 0.03 ppm, 0.07 ppm, 11 ppm, 630 ppm and 162.5 ppm respectively. Among the biofloc meal enriched diets, diet T1 with 20% biofloc yielded the best results in terms of average body weight gain, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER) and feed efficiency ratio (FER). The mean body weight gain recorded in T1 was 25.28±0.81 g. The results demonstrated that biofloc meal is a potential ingredient that can be incorporated in GIFT tilapia diet at 20% level for better growth performance.

In the present study, induced breeding of endemic barb, Dawkinsia filamentosa was carried out using three different synthetic hormones namely Human chorionic gonadotropin (HCG), WOVA-FH and Ovatide at different (0.3, 0.5, 0.7 and 0.9 ml/Kg) doses. All synthetic hormones showed good performance at 0.7 ml/kg body weight. Comparatively WOVA-FH showed better performance with higher number of spawned eggs (1405±5.74 nos/female) and hatching rate (90±0.6%). The study concluded that WOVA-FH at 0.7 ml/kg is an ideal for induced breeding of D. filamentosa. Fertilised eggs were golden in colour with an orange tinge. Hatching took place 34- 36 hrs (26±0.50C) of post fertilization. Yolk sac remained up to 60 hrs of post hatching. Complete developmental stages of D. filamentosa from egg to adult were recorded in captive condition. The present study aids in introducing hatchery-bred seeds of valuable indigenous fish Dawkinsia filamentosa into the ornamental fish trade. Availability of hatchery seed may reduce the wild exploitation and contributes to the conservation of the natural resources.

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A 60‐day indoor feeding trial was conducted to evaluate the effects of dietary tryptophan supplementation on growth performances, whole‐body chemical composition, expression of muscle growth‐related genes (MyoD, myogenin and myostatin), and haematological and biochemical responses of juvenile genetically improved farmed tilapia (GIFT). Five corn–soy‐based isonitrogenous and isoenergetic diets were formulated to contain graded levels of dietary tryptophan (2.6, 3.2, 3.7, 4.2 and 4.8 g/kg of diet). Each diet was randomly assigned to triplicate groups of 30 fish (5.3 ± 0.1 g) per experimental unit, which were fed thrice a day (9:00, 13:00 and 17:00 hr). Maximum growth performances and feed utilization were observed in fish fed tryptophan at 3.7 g/kg of diet. There was no significant (p > .05) effect on whole‐body composition and amino acid profile by dietary tryptophan supplementation. However, significant (p < .05) differences were observed in plasma metabolites and the mRNA expression of MyoD, myogenin and myostatin. Serum cortisol level was found significantly lowest in fish fed tryptophan at 3.7 g/kg of diet. Second‐order polynomial regression analysis of weight gain and nitrogen gain against dietary tryptophan levels indicated that the optimum dietary tryptophan requirement for maximum growth and feed utilization of juvenile GIFT tilapia was 3.8 g/kg of diet.

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Stocking density is one of the critical factors that influence the production and health status of fish in aquaculture practices. In this 60-day trial, effect of different stocking densities (70, 140, 210, 280 and 350 fish/m 3 ) on growth performance, digestive enzyme activity, body composition and gene expression of Asian seabass, Lates calcarifer, was studied using Recirculating Aquaculture System by following completely randomized design with four replications. Asian seabass (5.20 ± 0.10 g) were randomly distributed in 20 tanks, each of 500-L capacity, and fed four times a day (6:00, 12:00 18:30 and 23.00 h). The study found that growth performance and feed utilization efficiency were significantly decreased with increasing stocking density. A significantly higher survival (95.00 ± 1.25%) was recorded in the low stocking density group (70 fish/m 3 ). On the other side, fish reared in higher stocking densities (140, 210. 280 and 350 fish/m 3 ) displayed lower digestive enzyme activities, such as protease, amylase, lipase and cellulase. There is a significant density-dependent decrease in crude protein deposition in the fish body and the study found significantly higher protein (19.12 ± 0.10%) content in the 70 fish/m 3 . The relative gene expression of GH/ IGF axis and myostatin (MSTN) was significantly down-regulated and up-regulated, respectively, with the increasing stocking density. Overall, the study found that the increasing stocking density produced chronic stress which negatively affected the growth performance of the fish. Therefore, the study suggests that rearing of Asian seabass at a stocking density of 70 fish/m 3 in a recirculatory aquaculture system could improve the growth performance, metabolic and molecular activities of the fish.

A 10-week feeding trial was conducted to determine the effects of dietary black soldier fly larval meal (BSFLM) on growth performances, digestive enzyme activity, haematological responses and muscle growth-related gene expression of juvenile striped catfish (Pangasianodon hypophthalmus). Six isonitrogenous and isolipidic diets were formulated with BSFLM to replace fishmeal at 0 per cent (T0), 20 per cent (T20), 40 per cent (T40), 60 per cent (T60), 80 per cent (T80) and 100 per cent (T100). A total of 540 fingerlings were randomly distributed into 18 tanks and fed thrice a day. Growth performance and feed utilization of fish fed T20, T40 and T60 diets were not significantly different from T0 diet. However, increasing the percentage of fishmeal replacement with BSFLM to 100% at an inclusion level of 292 g/kg resulted in a substantial reduction in growth and feed efficiency of striped catfish. Fish fed T80 and T100 diets had significantly lower whole-body crude protein, crude lipid, total cholesterol and triglyceride value than fish fed other experimental diets, while dietary inclusion of BSFLM had no significant effect on the whole-body amino acid profile, haematological responses and intestinal and liver protease and amylase activity of striped catfish. However, lipase activity was increased in fish fed T80 and T100 diets. T80 and T100 hepatocytes were shown to have greater congestion in histology than other groups. The relative expression of MyoD and myogenin was significantly maximized in fish fed the T60 diet. Fishmeal may be replaced with BSFLM up to 60 per cent at an inclusion level of 174 g/kg in the diet of juvenile striped catfish.