Response to the ration levels on growth, body composition, energy, and protein maintenance requirement of the Indian catfish (Heteropneustes fossilis-Bloch 1974).

An 8-week growth study was conducted to determine the effect of ration level, energy, and protein maintenance requirement of catfish, Heteropneustes fossilis-Bloch, fingerling (7.90±0.55 cm; 3.10±0.28 g) by feeding casein-gelatin-based purified diet (40% CP; 3.61 kcal g-1 GE) at six ration levels 1-6% of BW/day, at 0800 and 1700 h, in triplicate, with 20 fish per trough fitted with water flow-through system of volume 55 L. Maximum live weight gain, best feed conversion ratio (FCR), best specific growth rate (SGR), and highest protein efficiency ratio (PER) were evident for ration levels of 4-5% body weight. However, second-degree polynomial regression analysis for weight gain, FCR, PER, protein, and energy retention data indicated that the break-points occurred at 5.08, 4.18, 4.05, 4.16, and 4.17% BW/day, respectively. Significantly (P<0.05) higher body protein content was recorded at 4 and 5% rations. While a linear increase in body fat content with inverse relationship in moisture content was evident with increasing rations. Ash content remained insignificantly (P>0.05) low at higher rations. Protein and energy retention values also produced significant (P<0.05) differences. Based on the results obtained, it is recommended that feeding in the range of 4 to 4.5% BW/day, corresponding to 1.60-1.80 g protein and 14.46-16.27 kcal energy g100 g(-1) of the diet/day is optimum for the growth and efficient feed utilization of H. fossilis, while 2-3% ration levels (0.80-1.20 g protein and 7.23-10.84 kcal energy) suggest that these amounts approximate to the maintenance requirement of this fish.