Effects of stocking density and food deprivation‐related stress on the physiology and growth in adult Scortum barcoo (McCulloch & Waite)

Two consecutive experiments were conducted to investigate the physiological responses of Jade perch (Scortom barcoo) to different stocking densities over a 30‐day period and to stress resulting from food deprivation over a 10‐day period. Groups of Jade perch were reared in recirculating tanks at three stocking densities (120, 180 and 270 fish m^?3). Fish were weighed and blood samples were taken at the beginning of the experiment (P1) and after 30 days (P2). Feeding was then stopped and fish were sampled again 10 days later (P3). Blood samples were analysed for serum level of cortisol (COR), glucose (GLU), total protein (TP), triglycerides (TG), lysozyme (LYS) activity and alkaline phosphatase (ALP) activity. Significant changes were observed in average body weight and serum COR, TG, LYS and ALP activity in response to stocking density. No significant difference was found between stocking density treatments concerning the serum TP and GLU. The results showed that fish performed better at a stocking density of 180 fish m^?3. Food deprivation for 10 days resulted in significant changes in ALP activity and LYS activity, TP and GLU concentrations and final average body weight but not in COR and TG levels.