Abstract

The mean concentration of some heavy metals (lead, cadmium and mercury) in the muscles and the organs of some common species of fish: Metacembelus Iconnbergii, Clarias lazera, Citarinus citharus, Tilapia zilli and Erpetoichithy were investigated using atomic absorption spectrophotometric method. The mean concentrations of lead in the muscle, kidney and liver were in the ranges of 0.00 – 0.004 mg/kg, 0.010 – 0.015 mg/kg, and 0.004 – 0.010 mg/kg respectively, while that of the surrounding waters were between and 0.001 – 0.005 mg/kg. Cadmium concentrations were in the range of 0.001 – 0.002 mg/kg in the muscles, 0.004 – 0.006 mg/kg in the kidney and 0.002 – 0.004 mg/kg in the liver while that of the surrounding water was 0.001 mg/kg. The levels of mercury were 0.001– 0.002 mg/kg in the muscle, 0.004 – 0.006 mg/kg in the kidney, 0.002 – 0.004 mg/kg in the liver and 0.001 – 0.002 mg/kg in the surrounding waters. From the results, it was observed that the levels of these metals in the fishes were higher than that obtained in the surrounding waters from which the fishes were obtained. The distribution of lead, cadmium and mercury in the fishes investigated showed significant variations with respect to the muscles and the organs. The kidney had higher concentration of the metals compared to the liver, which is in turn higher than that in the muscle. This indicates that the kidney of fish is a better bio-accumulator of heavy metals than the liver and the muscle. The accumulation patterns of heavy metals contaminants in fish depend on uptake and elimination rate. The implications of these contaminants beyond the World Health Organization (WHO) and Food and Agricultural organization (FAO) permissible limits were discussed.

Key words: Heavy metals, fish, lead, cadmium, mercury, contaminant.