TOXICITY, DISTRIBUTION, ACCUMULATION AND COOKING LOSS OF MALATHION IN TISSUES OF TILAPIA AND COMMON CARP FISHES

The acute toxicity of malathion as an organophosphorus pesticide to both of the tested fish species, i.e. Tilapia nilotica (tilapia) and cyprinus carpio (Common carp) was followed by estimating the LC50 at intervals from 24h up to 96h. Tilapia was much more susceptible to malathion toxicity when compared with carp and the available data proved that the LC50 of malathion to common carp fish was 5-7 times the LC50 for tilapia. Accumulation of malathion pesticide in some organs (muscles, gills, intestine and liver) of both fish species was studied after application of 200, 300 and 400 ppb malathion in water for 28 days. A proportional relation was found in the two fish species between exposure time and the applied concentrations. The rate of malathion accumulation was higher in liver followed by intestine and gills whereas the lowest concentration was found in muscles. Accumulated malathion in tilapia muscles was higher than carp; while a reversible trend was observed in most other organs. Cooking of the same fish species reduced effectively malathion content in their muscles. Frying of fish in oil lead to a higher loss percent of malathion than did the other methods of cooking.