Toxicity Assessment Of Challawa Industrial Effluent On African Catfish (Clarias gariepinus, Burchell, 1822) In Kano, Nigeria

Industrial effluents contaminate water bodies and harm aquatic biota. In this study, industrial effluent was collected from Challawa Industrial Area, Kano State and analyzed for physico-chemical conditions, heavy metals concentrations and impact on the survival of juveniles of Clarias gariepinus under standard laboratory conditions, using Completely Randomized Design (CRD) with three treatments (0.00ml/L, 5ml/L and 10ml/L) in three replicates. Test fish with a mean weight of 183.2g and a mean length of 24.1cm were purchased from Kano State Ministry of Agriculture and Mineral Resources, Department of Fishery and Aquaculture, Fisheries Unit and acclimated in 100L tank for 14 days. The test fish exhibited abnormal respiratory action, opercular movement, body movement and mucus secretion with increase in the concentrations of the effluent. The mean values of DO (2.59±0.05mg/L), temperature (29.0±0.10°C) and pH (10.28±0.00) varied slightly between the control and the effluent. The mean values for Turbidity, Total alkalinity, TDS, Electrical conductivity and Chloride were beyond FAO/WHO (2018) recommended limit with exception of temperature. Heavy metals concentration in the effluent was: Pb > Cu > Fe > Zn > Cd > Mn > Cr and decreased in gill and liver tissues (Fe > Zn > Cu > Mn > Pb > Cr > Cd). Exposure to varying concentrations of the effluents caused toxicity signs, death and considerable damage to tissues of C. gariepinus during the study period. The study recommends that regulatory bodies should adopt holistic approach on aquatic pollution abatement, due to its negative impact to non-target organisms.