Acute toxicity of glyphosate and paraquat to the African catfish (Clarias gariepinus, Teugels 1986) using some biochemical indicators

The impact of acute exposure of Clarias gariepinus juveniles to commonly used herbicides, glyphosate and paraquat was evaluated through changes in fish mortality and biochemical indeces. Juveniles of the African catfish were exposed to varying acute concentration of glyphosate and paraquat. After 96 h of exposure, the 96 h LC₅₀ for paraquat was found to be 0.07 mg/l while that of glyphosate was found to be 0.530 mg/l. After the exposure period, some enzymes were assayed for in fish liver using a combination of conventional methods and commercially available kits. Comparing with the control, ANOVA analysis revealed that there were significant (p < 0.05) increases in the activities of all enzymes assayed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). There were also significant (p < 0.05) increases in the activities of the antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and in lipid peroxidation, which was measured by thiobarbituric acid substances (TBARS). The result revealed that glyphosate and paraquat have the ability to modulate certain fish biochemical parameters and can therefore serve as reliable indicators of toxicity in environmental impact assessment programmes.