The effect of two sources of water, fresh water and drainage wa­ter on some microelements (Fe, Mn, Cu, B, Mo, Pb, and Zn) in fish farm was studied. Six earthen pods (0.36 ha each) were stocked with Nile tila­pia, mullet and commone carp. Each treatment was replicated in three ponds. Ponds were subjected to chemical fertilization ( urea-superphosphate) plus artificial feeding_ Results showed that drainage wa­ter was significantly higher than fresh water in Fe, Mn, B and Zn concen­trations, while, concentrations of Cu, Mo and Pb were not significantly different between the two water sources (P>0.05). No significant effect on all microelements in the surface layer was noticed except a significant increase in Cu and B with fresh water treatment. Drainage water treat­ment increased significantly Pb. En the subsurface layer, only B increased significantly with fresh water. Drainage water did not show significant ef­fect on all microelements. Phytoplankton abundance was better with drainage water. Ponds supplied with this source of water had higher net fish yield (1570.7 kg/0.36 ha) than ponds supplied with fresh water (1305.1 kg/0.36 ha). Net fish production of all polyculture species was significantly different among treatments except for common carp.