Heavy metal concentrations in Malapterurus electricus and Chrysichthys nigrodigitatus from Ogba River in Benin City, Nigeria

Abstract

The concentrations of heavy metals in two tropical fish species (Malapterurus electricus and Chrysichthys nigrodigitatus) from Ogba river in Benin City, Nigeria, were investigated between November 2002 and October 2003 in order to ascertain the pollution status of the river. The results showed varying levels of accumulation of Cu, Mn, Zn, Pb, Cr, Ni, and Cd in the fishes. The levels of Cu, Mn, Cr and Ni, in both fishes were higher than the WHO and FEPA recommended maximum allowable standards in food fish, while those of Zn, Pb and Cd were lower than the standards. The results suggest that the Ogba river system is contaminated with heavy metals and the consumption of fishes of the river could pose health hazards to man. Metal levels in water in Ogba River are lower than the recommended limiting standards and could be considered safe for drinking.   Key words: Heavy metals, bioaccumulation, fish, river, Nigeria.