Evaluation of silver perch (Bidyanus bidyanus, Mitchell) nutritional requirements during grow-out with high and low protein diets at two feeding levels

Silver perch (Bidyanus bidyanus, Mitchell) of 65 g average weight were rear ed at high density under controlled conditions on diets containing 24.8% an d 40.6% protein. Diets were fed at 2% or 4% of the fish biomass day(-1). Bo th protein concentrations and Feeding level of the diet influenced growth a nd proximate composition of the fish at the end of the 50-day growth trial. Energy requirement for maintenance for these fish was found to be 77 cal B W-0.8 and for each unit of energy retained 3.78 cal BW-0.8 needed to be sup plied. and for each gram of protein retained per metabolic body weight 5.04 g were required. The results indicate that it is possible to obtain the sa me weight increment when feeding a 24.8% protein diet at a level of 4% body weight day(-1) as compared with only 2% body weight day(-1) of a 40.6% pro tein diet. This study indicates that the nutritional requirements for early grow-out are similar to those found in a previous study with juvenile silv er perch and adds information concerning the required relationships between dietary amino acids. The results provide information required for further refinement of nutrition for this species.