Acute Toxicity, Behavioural Changes and Histopathological Effect of Paraquat Dichloride on Tissues of Catfish (Clarias Gariepinus)

The toxicity of Paraquat dichloride, a herbicide, was investigated with emphasis on histopathological effects of
African Catfish (Clarias gariepinus) juvenile. The fishes were exposed to 0, 20, 60, 80, 110 mg/l of Paraquat
dichloride .,The lethal concentration (LC50) value of Paraquat dichloride was 1.75mg/l for 96 h of exposure.
Histopathology of the organs after 96 hr exposure revealed cell proliferation, lamellar fusion, lamellar cell
hyperplasia, and epithelial lifting. In the liver, there was vacuolation of hepatocytes and necrosis. The changes in
these tissues occur predominantly in the 96 hr exposure. Respiratory stress, erratic swimming and instant death
of fish were observed in exposed fish, which varied with the concentration of the toxicant. Paraquat dichloride is
highly toxic to Clarias gariepinus, therefore its use near fish farms or in areas close to aquatic bodies should not
be encouraged.