Dietary protein requirement of Indian Butter catfish, Ompok bimaculatus (Bloch) fingerlings

A 60-d feeding trial was conducted to assess the dietary protein requirement of Indian Butter catfish, Ompok bimaculatus fingerlings. Five iso-energetic semi-purified diets were formulated with varying levels of crude protein (25-45%) and fed to the experimental fish (3.29 +/- 0.01 g) twice daily at satiation level in triplicate groups. Fishes were reared in indoor tanks with a stocking density of 11 fingerlings per tank. The results showed that the growth of the fish increased significantly (P < .05) with increasing protein levels upto 35% and decreased thereafter. Highest (P < .05) weight gain (247.25 +/- 5.76%), carcass protein content (16.78 +/- 0.04%) and protease activity (0.46 +/- 0.02) coupled with lowest FCR (1.62 +/- 0.04) were observed in the fish fed with 35% protein. PER and ANPR were found to decrease with increasing dietary protein levels (P < .05). Based on the second-order polynomial regression analysis of WG, it may be concluded that the dietary protein requirement of O. bimaculatus is 36.11% with a P/E ratio of 23.11 g protein MJ(-1) as indicated by the maximum growth.