Assessment of heavy metals in some selected fish species from River Niger, Illushi, Edo State, Nigeria

Abstract

This study was conducted in River Niger at Illushi, Edo State, Nigeria to determine the concentration of Arsenic, Cadmium, Iron, Manganese and Nickel in Bagrus bayad macropterus, Clarias gariepinus, Malapterurus electricus, Parachanna obscura, Synodontis batensoda and Synodontis budgetti. The sampling was done monthly from April to November, 2017. Heavy metal concentrations were determined using Atomic Absorption Spectrophotometer (AAS Bulk scientific VGP 210 model) according to the standard method. Synodontis budgetti accumulated the highest level of heavy metals (32.13%), followed by Bagrus bayad macropterus (19.72%), Clarias gariepinus (17.80%), Synodontis batensoda (10.68%), Parachanna obscura (10.61%) and the least was Malapterurus electricus (9.02%). The accumulation of heavy metals in the fish species was in the order Fe ˃ Ni ˃ Mn ˃ Cd ˃ As (B. bayad macropterus), Fe ˃ Mn ˃ Ni ˃ Cd ˃ As (C. gariepinus and S. budgetti), Fe ˃ Ni ˃ Mn ˃ As ˃ Cd (M. electricus, P. obscura and S. batensoda). Clarias gariepinus and Synodontis budgetti had Mn exceeding the limit, other fishes had concentration below permissible limit. The level of Ni, Cd and As in all the fishes were below the permissible limit, while the level of Fe in all the fishes exceeded the limit.