Growth, survival, and immune potential of post larvae of Indian white shrimp, Penaeus indicus (H. Milne Edwards, 1937) in different salinities with biofloc system (BFT) during nursery phase

Biofloc culture system is an eco-friendly method, because it limits the water usage and effluent discharge to the surrounding environment. The present study aimed to investigate immune potential, growth, and survival of Indian white shrimp Penaeus indicus, post larvae in the biofloc technology (BFT) with C:N ratio of 15:1 during nursery phase in different salinities (5 parts per thousand, 15 parts per thousand, 25 parts per thousand, 30 parts per thousand, and 35 parts per thousand). Experiments were conducted in triplicate in 100-L-reinforced fiber plastic (FRP) tanks, and P. indicus (post larvae 10) were stocked at the density of 120 numbers/tank (1.2post larvae/L). The total suspended solid (TSS) level in each biofloc group was maintained at 200-300 mg/L. The results showed that the final biomass and survival in each treatment were significantly higher in biofloc-reared shrimps when compared to clear water culture (p < 0.05). Among the salinity and BFT treatments, shrimps reared in 15 parts per thousand with BFT condition showed better growth and survival than other treatments and achieved a significantly higher final body weight (1.67 g +/- 0.067 g). Net shrimp production in terms of growth and survival was 50% higher in the BFT tanks (average body weight = 0.85 +/- 0.082 g to 1.67 +/- 067 g) than in the control tanks (ABW = 0.61 +/- 0.07 g to 0.98 +/- 0.07 g). The final survival observed in different biofloc system with varying salinity was significantly higher than respective clear water (CW) system. Total serum protein showed significantly higher levels (120.32 +/- 3.68 mg/ml) in 15 parts per thousand with BFT treatments than the other. The 15 parts per thousand with BFT (0.14 +/- 0.011OD/min) and 5 parts per thousand with BFT showed more pro-phenol oxidase levels (0.11 +/- 0.009 OD/min) of activity than other treatments. Total haemocyte count (THC) was calculated and the highest value of 6.33 +/- 0.33 x 10(6) showed in 15 parts per thousand BFT. In conclusion, the lower salinity rearing with biofloc did not show significantly lower growth than optimum range of salinity in case of Penaeus indicus post larvae.