Histopatologic Survey of Malathion on Liver and Gills Tissues in (Caspian Roach) Rutilus rutilus caspicus

In the present study, LC50 value of Malathion, an organophosphate insecticide, was determined in Caspian Roach (Rutilus rutilus caspicus). Also four groups of experimental fish (containing 30 fish in each group) were exposed to different concentrations of Malathion. 0, 0.01, 0.05 and 0/1 ppm respectively for 23 days and effects of Malathion on gill and liver tissues were examined. Each treatment has 3 replications. Tissue sampling to histological study was done in third, thirteenth, twenty-third days and also 30 days after recovery. Results showed that LC50 value of Malathion in Caspian Roach is 6.5 ppm. In addition tissues of control group (0ppm) were normal and there were no damages, yet there were hepatocytes degeneration, picnotic in nuclear, hepatocytes vacuolization, vascular congestion and sinusoid congestion in liver of other groups and lamella hyperemia, hyperplasia, lamella fusion, necrosis lamella, increasing in mucosal cells, clubbing and telangioctasia in gills. There were more damages in longer times and in higher concentrations.