The acute toxicity and histopathological changes in the gill and liver of Clarias gariepinus juvenile exposed to Herbex-D SL ®, a herbicide containing 720g/l of 2, 4-D amine were investigated. In a static renewal bioassay, the fish were exposed to 0.00, 1.40, 1.44, 1.48 and 1.52mg/l of 2, 4-D amine. The 96 hours lethal concentration (LC50) of 2, 4-D amine to juvenile of Clarias gariepinus was 2g/l. The fish exposed to 2, 4-D amine showed toxicological signs of erratic swimming, loss of reflexes and lethargy. Histopathological changes in the gill architecture were characterized by lifting of epithelia layer, vacuolization, inter-lamella hyperplasia and mild desquamation of the epithelia lining. There was an evidence of advancing phase of hepatic necrosis in the liver of fish exposed to 2, 4-D amine. 2, 4-D amine is highly toxic and its use in or near aquatic environment should be monitored. Key words: 2,4- D amine (Herbex D SL®), Clarias gariepinus, Acute toxicity, Histopathology
