ABSTRACT
This research work was conducted to assess the levels of heavy metals namely; (Copper, Zinc, Nickel, Iron, lead, cadmium, chromium) in Cat Fish (Clarias gariepinus) from selected fish ponds in Benin City, Edo State, Nigeria. Heavy metal toxicity is increasing in fish organs due to their susceptibility over time. Heavy metals (cadmium, Chromium, zinc, lead and copper) are ingested by fishes due to natural and human activities and bioaccumulate in these organs after absorption. There is apprehension of heavy metal toxicity in fish organs due to the metal based farm implements used overtime during their breeding periods. Clarias gariepinus has been widely consumed in Nigeria with no clear cut on bioaccumulated heavy metals impact on consumers' health. This study, therefore, examines the level of heavy metal in C. gariepinus. The levels of Cu, Cr, Cd, Pb, Fe, Ni & Zn fifteen fish samples from five farms located in Benin City were evaluated for using atomic absorption spectrophotometer. Data were analyzed using one-way ANOVA. Results showed that the concentration of Cd and Pb were low and within acceptable WHO and FEPA limit (0.040±0.053 and 0.003mg/kg respectively) and in a tolerable range. Cr and Cu maximum concentrations in the samples were (0.076±0.099 and 15.13±0.058) and within WHO and FEPA tolerable limit (0.50mg/kg and 40mg/kg). Zn is an essential heavy metal and the Zn concentration in the catfish samples analyzed was between (1.342±0.015 and 1.986±0.348), the values obtained pose no threat as the WHO maximum limit is 30mg/kg. The concentration of Fe which is also an essential heavy metal was high in the fish samples which range between (10.70±1.201 and 11.60±1.201mg/kg) but was below the expected maximum daily limit (30mg/kg) for humans and posed no toxicological risk. Ensuring the safety of the fish for consumption and these measures includes continuous close monitoring of heavy metal pollution, use of quality feeds and proper waste management and minimizing the use of metal based farm implement. From the foregoing it appears that the catfish in the local fish ponds at the moment are safe for consumption and do not pose any toxicological risk on consumption.
