Toxicity bioassay and effects of sub-lethal exposure of malathion on biochemical composition and haematological parameters of <i>Clarias gariepinus</i>

Abstract

Clarias gariepinus were exposed to different concentrations of malathion to determine the 96 h LC₅₀ value and its sub-lethal effects on haematological parameters and biochemical composition were also investigated. The 96 h LC₅₀ value concluded was 8.22 mg/L. Specimens of C. gariepinus were exposed to sub-lethal concentrations (0.5, 1.0 and 2.0 mg/L) of pesticide for 4 weeks, which revealed that the pesticide had an adverse effects on various blood parameters. Red blood cell (RBC) and white blood cell (WBC) counts, hemoglobin (Hb) concentration and haematocrit (Ht) values decreased after the exposure of malathion. Plasma glucose level was elevated as plasma protein decreased. Liver and muscle glycogen also decreased in the fish exposed to Malathion. Alanine amino transferase (ALT), glutamate oxaloacetate transaminase (GOT) and glutamate pyruvic transaminase (GPT) activities increased in the fish exposed to malathion. Magnesium and calcium ions were also affected, but the effects were insignificant.

Keywords: Malathion, bioassay, sub-lethal exposure, Clarias gariepinus, biochemical and haematological changes