protein efficiency ratio (PER) is used as an indicator of protein retention of conversion ratio. FCR and PER both are related to dietary protein intake and its conversion into fish weight gain (Koumi et al., 2009). In the present study, there were no significant effect on FCR and PER among the three experimental diets fed by tilapia fish. Rice polish (8BDT/kg) and mustard oil cake (19 BDT/kg) are very cheap in the local markets of Bangladesh. Therefore, partial replacement of fish meal by rice polish (up to 20%) and mustard oil cake (up to 22%) would be economically efficient by reducing about 24% of the feed formulation cost without changing the nutritional quality.