摘要：Cypermethrin, the synthetic pyrethroid commonly used as a pesticide, contaminates the aquatic ecosystem as a toxicpollutant from agricultural and domestic washouts. The aim of the study was to investigate the toxic effect ofcypermethrin on intestine and liver tissues in the tilapia fish Oreochromis mossambicus exposed to sublethalconcentration of 0.008ppm at different exposure time from 24 to 192 hrs. The histological observations of the intestineshowed deleterious effect of cypermethrin at 96 hrs exposure time, the epithelial cells and the cells of the outer walldisintegrate which would eventually result in the breakdown of the intestinal functions. Similarly the histologicalpreparation of the liver tissue showed damaging effect of cypermethrin on the hepatocytes that were altered withpycnotic nucleus. The break down in the function of the hepatocytes influences the distribution of nutrients to the othervital tissues and the survival of the fish. The deleterious effect of pesticide cypermethrin on increase in concentration ortime of exposure may affect the survival of the fish. Hence the LC50 of the fish tilapia which was calculated at 96hrsexposure as 0.04ppm clearly indicated the lethal effects due to alterations in the metabolic pathways of the tissues bydirect and indirect exposure of cypermethrin to the fish
