Evaluation of Effect of the Different Stocking Densities on Growth Performance, Survival, Water Quality and Body Indices of Pearlspot (Etroplus suratensis) Fingerlings in Biofloc Technology

Background: This experiment was conducted to evaluate the effect of different stocking density on growth performance, survival, water quality and body indices of E. suratensis fingerlings for 90 days at PRFF, Pazhaverkadu. Methods: Three different stocking densities are 100, 200, 300 no of fishes/m(3). The fingerlings of pearlspot, E.suratensis with an average body weight of 5.05 +/- 0.03 g were stocked at a rate of SD-1 (100/m(3)), SD-2 (200/m(3)) and SD-3 (300/m(3)) culture for a period of 90 days. Result: The growth parameters were found to significantly decrease with increasing stocking density in the biofloc rearing system. Result of Nitrite and nitrate concentrations were significantly lower in the BFT treatment with lower stocking density than in higher stocking density (P<0.05). The highest mean body weight gain recorded in SD1 (42.37 +/- 0.04 g) followed by SD2 (29.98 +/- 0.08 g) and SD3 (20.85 +/- 0.06 g). BFT significantly increased fish specific growth rate and net yield. There was no significant difference in hematology analysis (in terms of white blood cell and red blood cell counts, hemoglobin and hematocrit levels), total superoxide dismutase activity of fish between different stocking density (P>0.05). Second-order polynomial regression analysis of weight gain against pearlspot culture under lower stocking stocking density (100/m(3)) indicate that biofloc technology culture with lower stocking density can improve the growth performance and immune response and also the maintenance of good water quality and improvement of feed utilization of pearlspot.