Toxic effects of animal manures and sewage sludge as supplementary feeds for the common carp. Cyprinus carpio.

Activated sludge, chicken manure and pig manure were tested for their toxic effects as supplementary feeds for the common carp, Cyprinus carpio. The acute toxicity test showed that animal manures were more toxic than activated sludge (e.g., 96-h LC50 values for pig manure and chicken manure were 0.55% and 0.29%, respectively, while no effective value was revealed for activated sludge). This may be due to the inadequate processing of the manures which resulted in the release of harmful substances during decomposition. In general, body weights of all the fish fed the wastes decreased during the culture period. High heavy metal concentrations (Pb, Cu, Zn and Mn) were found accumulated in the flesh of the fish fed the wastes. It is suggested that waste materials should be pretreated and detoxified before using them as animal feeds.