Effect of Zinc on Haematological Parameters of African Catfish (Clarias gariepinus)

Zinc is one of the hazardous heavy metals which can cause serious health hazards in man when ingested in high quantities. Its natural occurrence in soil and water makes freshwater fish species to accumulate it in their flesh where it causes serious physiological disorders. This study monitors the effect of zinc toxicity on the haematology of the African catfish, Clarias gariepinus exposed to two concentrations (T₁ 0.08mg/l and T₂ 0.15mg/l) of Zinc sulphate (ZnSO₄) and monitored at 24 hour interval (24h, 48h, 72h, 96h and 120h). Parameters analyzed included packed cell volume (PCV), percentage haemoglobin (% Hb), red blood cell (RBC), white blood cell (WBC), erythrocyte sedimentation rate (ESR), mean cell volume (MCV fl), mean cell haemoglobin (MCH pg), percentage mean cell haemoglobin concentration (%MCHC), percentage lymphocytes (% Lym) and percentage neutrophil (% Neu)t.Results showed a decrease in values of PCV, %Hb and RBC while parameters such as WBC, ESR and %Lym increased as a result of the exposure. MCHC and Neut remained fairly constant throughout the experimental period. 100% mortality was recorded at 120h of exposure in concentration T₂. Results obtained from this study showed that zinc triggered haematological responses in Clarias gariepinus