Toxicity Potential of African Cat Fish (Clarias gariepinus) Tissues: A Comparative Study ofRiver Galma, River Kubanni and Fish Farms in Zaria, Nigeria

Concentration of some heavy metals; Lead (Pb), Copper (Cu) and Zinc (Zn), in the head, gills, liver and muscle tissues of Clarias gariepinus from River Galma, River Kubanni and some fish farms in Zaria, Nigeria, were determined using atomic absorption spectrophotometer (AAS), after wet digestion. The concentration of the metals differed significantly (ANOVA; p < 0.05) among the four fish tissues. Fish liver and gills appeared to have significantly higher tendency for the accumulation of these metals, while muscles had minimum concentrations. The difference in metal concentrations between the three locations were not statistically significant (ANOVA; p > 0.05), the difference of lead concentration between River Galma and fish farms being the only exception. The trend of metals concentration could be represented as: Cu > Zn > Pb. The mean of total concentrations was; lead 1.55 mg/kg, zinc 3.57 mg/kg, copper 5.75 mg/kg for River Galma, lead 0.5 mg/kg, zinc 3.86 mg/kg, copper 5.75 mg/kg for River Kubanni and lead 0.28 mg/kg, zinc 1.0 mg/kg , copper 5.21 mg/kg for fish farms. Comparison of these values with Food and Agricultural Organization (FAO) limits in fish tissue, Codex Committee on Food Additives and Contaminants maximum levels (CCFAC) and Health criteria established by the United States Environmental Protection Agency (US EPA) for human health risk for carcinogens shows that it is unsafe to consume Clarias griepinus tissues from River Galma and River Kubanni with respect to lead toxicity. Copper and zinc were however not implicated in the study.