Trace metal accumulation in Clarias gariepinus (Teugels) exposed to sublethal levels of tannery effluent.

The concentration and distribution of Cr, Cu, Pb and Zn among the tissues of a freshwater fish, Clarias gariepinus exposed to combined (composite) tannery effluent was investigated at two sublethal concentrations (2 and 6%) in static bioassay for 8 weeks. The distribution of the four metals in fish was of the order of Pb > Cr > Cu > Zn and the accumulation was found to be dose- and time-dependent. The metal levels in the liver were significantly higher (P > 0.05) than other tissues. This was followed by the gill and the gut. Relatively low accumulation of these metals was found in muscle tissue.