Biofloc effects on body composition, plasma protein, lipid profile, zooplankton community, and economics of Nile Tilapia fingerlings reared under different stocking densities

This study aimed to investigate the effects of biofloc on body composition, plasma protein, lipid profile, zooplankton community, and economics of Nile tilapia fingerlings in different stocking densities. Three stocking densities (200, 300 and 400 fish/m³) under biofloc system (BS) and clear system (CS) were applied. Nile tilapia with an initial body weight of 20.35 ± 0.35 grams were stocked in 18 cylindrical fiberglass tanks with a water volume of 50 liters for 75 days. Starch was added on Biofloc system treatments as a carbon source to set the C / N ratio at 15/1. Body proximate composition showed that the highest protein and ash content were recorded in the highest stocking density (400/m³). The highest fat content was noticed in the lowest density of 200/m³. For system conditions, the biofloc system showed significantly higher dry matter, fat, and ash content, compared to the clear water system. Biofloc sample analysis showed an increase in protein, fat, and ash contents with increasing stocking density. The highest stocking density of 400/ m³ showed the highest significant (P<0.05) total protein, albumin, and globulin. Plasma total cholesterol, triglyceride, HDL, and LDL were all significantly higher in the lowest density (200/m³) than the other treatments. Biofloc system results recorded significantly higher total protein, albumin, globulin albumin/globulin ratio than the clear system. In addition, cholesterol triglyceride, and LDL were significantly increased with BFT treatments. All biofloc treatments showed higher zooplankton count, when compared with the clear system. Under biofloc conditions, increasing stocking density led to an elevation in zooplankton count as the highest was recorded for a density of 400 fish/m³. Three groups of organisms were identified, Rotifera, Protozoa, and Copepoda. Economical benefits in terms of feed costs and relative feed costs per kg of fish were recorded in the treatments of (BS) with superiority of stocking density of 200 fish/ m³ under these experimental conditions.