He added that the target tissues of heavy metals are metabolic active ones which accumulate high level of metals such as liver, kidney and gill. While muscles and skins accumulate less level of metals, due to low metabolic activities. The results obtained from this study was in line with the earlier work of Etim (2005) who observed the high values of trace metals in liver, gills and kidney of Chrysichthys nigrodigitatus obtained from crude oil polluted water. However, livers are thought to play an important role in detoxifying poisons and protecting the organisms from damage by heavy metal toxicants. Also, gills are the site directly exposed to the ambient conditions and also are known for their excretory function (Matthiessen
and Brafield, 1977). Etim (2005) reported that the amount of pollutants in the fish liver is directly proportional to the degree of pollution in the aquatic environment by heavy metals.
Similar observations were reported by many studies carried out with various fish species
(Guerrin et al. 1990 ; Saeed and Sakr, 2008).