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A study was conducted to evaluate the effect of different fertilizers in GIFT Tilapia culture using biofloc technology. Animals (5±0.23g) were stocked at a density of 30m-3 in 500 litres FRP tanks and spentwash was used as a carbon source to maintain a C:N ratio of 10:1 for 42 days. The experimental group includes fertilization using ammonia sulphate alone (T1) and fertilization using different inorganic fertilizers (T2). No significant differences in FCR, specific growth rate, weight gain and survival of animals were found between the treatments. Proximate composition and fatty acid profile of floc were comparatively rich in T2. Increased solid concentrations with higher Floc volume index and floc sizes were recorded in T2. The rapid floc development along with multiplication of heterotrophic bacteria and decreased vibrio population was observed in T2. The present study confirmed the influence of fertilizers on the physical and nutritional quality of biofloc in GIFT tilapia culture.

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Background: The study aimed to investigate the growth performance of Penaeus vannamei PL through the supplementation of fatty acid enriched Artemia franciscana.Methods: The animals were stocked at 3000PL/m3 in triplicates. The experimental diet (100nauplii/PL/day) fed initially for 7days include Artemia franciscana (unenriched) as control and Fatty acid (0.5%, 1%, 2% and 3 %) enriched nauplii as treatments (T1, T2, T3 and T4) and later switched to commercial diet for 18 days.Result: No significant difference in water quality parameters between the experimental groups was observed. Highest weight gain percentage and survival was found in T3. Fatty acid profile of Artemia franciscana and shrimp at day 7 and 25 were analysed. Higher W-6 fatty acid accumulation was found in shrimp on day 7. Histological analysis of muscles, hepatopancreas and intestine showed different fatty acids levels reflected structural changes in epithelial cells. The current study revealed that Artemia franciscana enriched with 2% fatty acid emulsion can be used as an optimum level to improve the zootechnical performance of P. Vannamei.

A study was conducted to investigate the probiotic potential of the bacterial species from biofloc reared genetically improved farmed tilapia (GIFT) using in vitro quantitative assays. Based on the morphological, biochemical and 16S rRNA sequencing analysis, isolated bacterial species from GIFT gut were identified as Bacillus infantis, Exiguobacterium profundum, Bacillus subtilis and Bacillus megaterium. The in vitro probiotic properties such as bile salt hydrolase activity, bile tolerance, growth at different bile concentrations, antibiotic susceptibility test, antimicrobial activity, auto aggregation test, bacterial adhesion to hydrocarbons and resistance to gastric acidity were performed. All the isolates showed higher resistance to bile tolerance test and growth of cultures was observed from 0.5 to 8% bile salt concentrations. The distinct zone of hydrolysis was marked in the tested isolates in bile salt hydrolysis activity. Except B. infantis, all the other three isolates were predominantly resistant to the tested antibiotics. Antimicrobial activity against three pathogens, viz. Vibrio parahaemolyticus, Vibrio harveyi and Aeromonas hydrophila was observed in all the isolates. E. profundum and B. subtilis showed improved auto aggregation. Enhanced resistance to bile salt adhesion to hydrocarbon and in vitro gastric acidity (pH 3) was seen in B. megaterium. It is one of such unique studies confirming the probiotic effect of Bacillus sp. isolated mainly from GIFT biofloc culture. B. subtilis and B. megaterium exhibited remarkable in vitro probiotic properties and thus can be recommended as a successful probiotic strain for fish farming.

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The present study aimed to isolate and characterize the Extracellular polymeric substance (EPS) producing bacteria from biofloc reared Nile tilapia (Chitralada) ponds. Distillery spentwash was used as a carbon source to maintain the C: N ratio at 10: 1 in the fish culture ponds and screening of bacteria were done fortnightly in 180 days culture. Out of 38 bacterial isolates, 7 isolates were found to produce EPS. Based on 16s rRNA sequence analysis the isolates were identified as Bacillus subtilis, B. megaterium, B. infantis, B. cereus, Pseudomonas balearica, P. mendocina and P. alcaligenes. The highest production of EPS was recorded in B. cereus (1.25 g/L). EPS extracted from Bacillus cereus was reported to have higher protein (89 μg/ml) and B. subtilis possessed higher carbohydrate (753.75 μg/ml). Maximum flocculating ability of 40.18% in B. cereus and higher emulsifying activity of 63.53% was observed in B. megaterium. The EPS extracted from B. infantis showed lower sludge volume index on its treatment with aquaculture sludge (15.38 ml/g). Absorption band in the range of 4,000/cm to 450/cm using FTIR analysis confirmed the presence of characteristic functional bands arising from polysaccharides, nucleic acids and proteins. The results indicated the presence of EPS producing bacteria in biofloc based Nile tilapia aquaculture systems.