Bioaccumulation of some trace element (Zn, Fe, Pb and Cu) in the gills and tissues of Clarias gariepinus and Oreochromis niloticus in River Ogbese, Ondo State, Nigeria

River Ogbese support many human activities (domestic, agricultural, fishing, industrial activities) leading to its extensive contamination and accumulation of heavy metals which can cause both environmental and public health hazard. In order to ascertain the quality of the river, a study was carried out to determine some trace element concentration (Zn, Fe, Pb and Cu) in gills and tissues of Clarias gariepinus and Oreochromis niloticus, being the most dominant fish species in the water body. Thus, ten samples each of C. gariepinus (21.0 – 37.4TL, 171.7 – 305.8 g) and O. niloticus (15.2 – 20.6 TL, 70.8 – 150.5 g) were collected from River Ogbese and the concentration of Zinc, Iron, Lead and Copper were analyzed both in the gills and the flesh using atomic absorption spectrophotometry (AAS). The study revealed that the highest concentration of iron was obtained in the gills and tissues of both fishes; C. gariepinus (gill - 6.70-4.23±0.72, tissue - 6.84 - 5.27±0.44) and O. niloticus (gill - 6.79 - 1.89±1.42, tissue - 5.83-4.27±0.58). The metal concentration occurred in the order Fe>Zn>Cu>Pb. In general, accumulation of the essential elements; Zn, Fe, Cu were higher than the non-essential elements; Pb. This could be due to the fact that these essential elements are naturally abundant in Nigeria soil. The bioaccumulation of zinc and lead are significant (P>0.05) in the tissues of both species while iron varies significantly (P>0.05) in their gills. There is no significant variation (P<0.05) observed among zinc, lead and copper accumulated in the gills of both species.   Key words: River Ogbese, heavy metals, Clarias gariepinus and Oreochromis niloticus.