Abstract

The toxicity of sublethal concentrations of effluents from a soap and detergent industry were investigated on African catfish Clarias gariepinus using a renewable static bioassay. The trend of bioconcentration of metals in the muscle and gut of the test organisms differs significantly (p < 0.05) and it followed the order, gut > muscle. The result revealed that the muscle had the least concentration of manganese at 0.1 x 10^-3 mg/kg and 10.7 x 10^-3 mg/kg recorded for zinc as the highest. While the highest iron concentration of 15.80 x 10^-3 mg/kg was recorded in the gut tissues of C. gariepinus, but mercury had the least concentration of 1.00 x 10^-3 mg/ kg. It was revealed that fish can bioaccumulate heavy metals from a polluted environment, which may result in impairment of natural population size; thus consumption of fish from such polluted environment should be discouraged.

Key words: Bioconcentration, Clarias gariepinus, effluent, toxicity.