LAUSR

Abstract A growth trial based on growth performance, non-specific immune response, digestive enzymes and antioxidant status, haematological parameters, body composition, and liver vitamin C concentration was carried out to estimate the dietary vitamin C requirement by feeding test diets (450 g/kg CP, crude protein, 18.71 MJ/kg GE, gross energy) containing graded levels of vitamin C (0, 10, 20, 30, 40, 50, 60 and 80 mg/kg) to fingerling Channa punctatus (5.7 ± 0.11 g) to satiety at 09:30 and 16:30 h for 12 weeks. Optimum live weight gain, LWG (820.4%), feed conversion ratio, FCR (1.46), protein efficiency ratio, PER (1.52) and protein deposition, PD (27.22%) were recorded in fish fed diet with 40 mg/kg vitamin C. Significant increase was recorded in hematocrit, haemoglobin and red blood cell counts of fish fed diets with vitamin C up to 40 mg/kg. Vitamin C levels in diets affected liver superoxide dismutase and catalase activities significantly and were found to be increased up to 50 mg vitamin C per kg diet. Also, the highest lysozyme, tissue serum protein, alkaline phosphatase, and intestinal enzymatic activities were noted at this level of dietary vitamin C. Liver vitamin C concentrations increased linearly (P