Dietary arginine requirement of fingerling Indian catfish (Heteropneustes fossilis, Bloch)

An 8-week feeding trial was conducted to determine the dietary arginine requirement of fingerling Indian catfish, Heteropneustes fossilis (6.25 ± 1.30 cm, 4.8 ± 0.65 g). Six isonitrogenous (400 g Kg^?1) and isoenergetic (17.90 kJ g^?1) amino acid test diets were formulated with gradation of 2.5 g Kg^?1 containing graded levels of l-arginine (8.5–21.0 g Kg^?1, dry diet). Fish were randomly stocked in triplicate groups, in 75-l circular trough with flow-through system and fed experimental diets at 4 % BW/day at 0800 and 1800 h. Maximum live weight gain (277 %), best feed conversion ratio (FCR) (1.52) and protein efficiency ratio (PER) (1.64) were obtained in fish fed diet containing 16.0 g Kg^?1 arginine. However, quadratic regression analysis of live weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary arginine at 16.80, 16.30, 16.11 and 16.10 g Kg^?1 of dry diet, respectively. Significantly (p < 0.05) higher whole body protein content, minimum carcass moisture and intermediate carcass fat contents were recorded at 16.0 g Kg^?1 dietary arginine diet. Ash content remained insignificantly (p > 0.05) low among all the treatments except at diet I and diet II. Based on the above results, it is recommended that the diet for young H. fossilis should contain arginine at 16.32 g Kg^?1, dry diet, corresponding to 40.80 g Kg^?1 dietary protein for optimum growth and efficient feed utilization.