Abstract Two new supplementary diets prepared by replacing groundnut oil-cake completely and rice bran partially from the traditional diet (TD) used in India (rice bran, 66·6%; groundnut oil-cake, 33·3%) with some widely available wastes and by-products were tested for their efficacy in 200 days carp culture. The effects of these diets on the survival, growth and yield and maturity of fish are published elsewhere. Results on flesh composition are presented in this paper. The flesh composition of carp fed with TD, diet A (rice bran, 50%; kitchen garbage, 25%; mushroom spent wheat straw, 5%; poultry droppings, 5%; fish meal, 2·5% and cheese whey, 12·5%) and diet B (rice bran, 25%; kitchen garbage, 25%; mushroom spent wheat straw, 12·5%; poultry droppings, 12·5%; slaughterhouse waste, 7·5%; fish meal, 5%; and cheese whey, 12·5%) was not much different. On the basis of the existing differences, however, diet A produced better quality flesh with maximum protein, minimum carbohydrate and low fat and ash contents. Diet B produced poorer quality flesh with minimum protein, high carbohydrate and maximum fat and ash contents.