A feeding field experiment was conducted for 102 days, using a polyculture system (Nile tilapia, silver carp, common carp, and African catfish at a rate 1: 1: 1: 1) in two Hapas, one for control fish fed a commercial diet and the second one fish were fed on a dried sewage sludge (DSS). The control diet, DSS, fish body and muscles
were analyzed for metals contents. Throughout the experimental period, any symptoms and death cases were recorded. From the obtained results, it was clear that DSS contained very high percentage of ash and very low percentages of ether extract (EE) and total carbohydrate percentages comparing with the diet of the control group.
It was found that DSS contains higher levels of P, Cu, Pb, and Cd than the commercial control diet. The P and Cd levels were higher in DSS fed fish than the control ones, regardless of the fish species. However, catfish body contained the
highest level of P and Cu but silver carp body contained the highest Pb and Cd levels.
The interaction effect (dietary treatment × fish species) was significant, except for Cu.The control fish muscles presented higher contents of Cu, Pb, and Cd, but the opposite  was true for P, where the DSS fed fish contained significantly higher level of P in their muscles than the control fish, silver carp contained significantly higher Cu and Cd and tilapia contained the highest level of Pb in the muscles comparing with the other fish species, regardless of the dietary treatment. The interaction effect was significant. Fish fed on DSS were darker with friable livers comparing with the control fish. Concerning mortality rate, when the fish were fed on the DSS, silver and common carps were more tolerant than the Nile tilapia and catfish. Therefore, it is recommended to give more concern on food and water quality (environmental
friendly) used in aquaculture to offer safe products for human consumption.