Similarly, 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.