Behavioural and Haematological Alterations in the African Catfish (Clarias gariepinus) Exposed to Varying Concentrations of Glyphosate

Extensive use of herbicides poses a serious threat to aquatic life due to runoff from treated fields. A static bioassay method was used to evaluate the toxicity of acute exposure to glyphosate on Clarias gariepinus behaviour and haematological parameters. Glyphosate was tested at varying concentrations (0.72, 1.44, 2.16, and 2.88 mg/l (control), 0.72, 1.44, 2.16, and 2.88 mg/l) for 96 hours in the laboratory. Significant (P < .05) dose-dependent behavioural and morphological changes of respiratory disturbance, erratic swimming, loss of equilibrium, mucous secretion, and mortality were recorded in the surviving fish. Erythrocyte (RBC), haemoglobin (Hb), packed cell volume (PCV) and leukocyte (WBC) values decreased significantly (P < .05) in treated fish as compared with controls. Mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) were not significantly different (P >.05) between the treated and control fish. Insignificant dose-dependent changes in the counts of neutrophils, monocytes, basophils, and eosinophils were also induced by glyphosate. The variations seen in this study demonstrated that glyphosate had a detrimental effect on the health of the fish. Educating farmers on recommended modes for the administration of glyphosate-herbicides on farmlands should be implemented and enhanced.