Glyphosate Toxicity: Effects on the Behavioural and Growth Responses of Juvenile Clarias gariepinus

Glyphosate is a broad spectrum herbicide used primarily in agricultural applications for the control of variety of weeds in both terrestrial and aquatic environments. Pollution of aquatic habitat may result in mass fish mortality or affect the physiology and survival of fish. Thus, this study evaluated the effects of exposure of juveniles of the African catfish, Clarias gariepinus, to sub-lethal doses of glyphosate, to determine its effects on the behaviour and growth response. Eight fish samples were introduced into individual plastic tank containing 0.00 ml (control), 2 ml/L (Treatment 1), 4 ml/L (Treatment 2), 6 ml/L (Treatment 3) and 8 ml/L (Treatment 4) of glyphosate in triplicate for 28 days. The physico-chemical parameters of water were within the permissive limits for aquaculture. However, the presence of herbicides in the water threatened the fish’s survival, which had detrimental impacts on the experimental fish that could be seen. According to this study, fish exposed to glyphosate displayed a variety of abnormal behaviors, including erratic swimming, loss of equilibrium, restlessness, respiratory distress, paleness/bleaching of the skin, and gasping for oxygen. In contrast, fish samples in the control group did not exhibit any discernible behavioral changes. Also, the weight of exposed fish did not increase significantly (P < 0.05) with period of exposure. This study concluded that glyphosate is highly toxic to Clarias gariepinus (because of the erratic behaviours and mortality that was directly proportional to concentration and exposure duration). Therefore, indiscriminate application of glyphosate (as well as other herbicides) should be totally discouraged.