Background. In Indian carp culture, a 1 : 1 mixture of rice bran and oil cake is traditionally used as feed in powder form; it is nutritionally inadequate and also a large part of it goes unutilized as the fish cannot feed on the powder effectively. With a view to improve its nutritional quality and reduce the wastage, the mixture was supplemented with soya and maize flours and converted into pellet form. The performance of the supplemented diets was evaluated by feeding them to catla, Catla catla, one of the popular Indian major carps. Materials and methods. Two test diets were formulated supplementing the feed mixture with soya flour (10% and 20%) and maize flour (39%), replacing equal quantities of rice bran and oilcake. These diets along with the control diet were fed to triplicate groups of catla fry maintained in outdoor cement tanks for 120 days. Results. The test diets enhanced growth and net fish production significantly (P < 0.05). This resulted in higher economic returns under the two test treatments. Survival of fish ranged from 74% to 76%.  Carcass of fish receiving the test diets had significantly (P < 0.05) higher lipid and lower moisture levels. Digestive enzyme activity was affected positively (P < 0.05) by the test diets. Conclusion. Replacing rice bran and oilcake from the traditional feed mixture with soya and maize flours proved economically viable.

Catla catla, feed mixture, growth, carcass composition, digestive enzyme activity