The effects of fertilizer types and stocking density were investigated on water quality parameters that expected to affect growth performance of the polyculture of Nile tilapia (Oreochromis niloticus) , African catfish (Claris gariepinus) and sliver carp (hypophthalmichthys molitrix). The purpose of this study was to determine the best type of fertilizer to use and stocking density to apply which maximizing fish yields while minimizing expenses and environmental degradation.