ABSTRACT

 The acute toxicity of cypermethrin to juvenile catfish (Clarias gariepinus) was investigated with emphasis on the histopathological effects. Clarias gariepinus was exposed to 0,20,40,60,80 and looppm of cypermethrin, the lethal concentration was 50.l2ppm ith lower and upper limit 0.6688 and 2.542.The threshold value was 9.977ppm for 96h of exposure. The dilution of the solution was made as follows: one gram of the pollutant was vigorously stirred in 1 litre of borehole water in a glass flask using a glass rod. This dispersion became the mother solution. Then lml of this stock solution was introduced into 9m1 of bore hole water (10 times d11uti6n) and after stirring, lml of diluted solution was removed and introduced into 99m1s of bole hole water (100 times dilution) again, imi was extracted from this and introduced into 999m1s of bole-hole water (1,000, 000 times dilution). This third dilution was the stock test medium (stm) from which the different experimental treatment was obtained. The concentrations used were 0, 20, 40, 60, 80, andloOppm respectively. Cypmethrin concentration corresponding to the 96h LC5O value for juvenile C. gariepinus was in inducing histopathological changes of gill, liver and intestine. There were fatty infiltration of the liver cell, massive fatty infiltration of liver cell observed in lOOppm concentration, necrosis and cellular infiltration of the intestinal epithelium and mild cellular Infiltration of the gills. These changes occurred predominantly in the 96h exposure respiratory stress erratic swimming and instant deaths of fish were observed in exposed fish, which varies with the concentration of the toxicant and its showed that the mortality increase with increases in concentration. The samples of dead fish were collected and fixed in formaldehyde to preserve them in a life-like manner. The tissues were later processed for histopathological examination. The result of this study revealed that cypermenthrin is toxic to fish.