Bioaccumulation Pattern of Selected Heavy Metals in Three Fresh Water Fishes from River Niger in Kogi State, Nigeria

This study was aimed at determining the level of some heavy metals (Cu, Zn, Pb and Ni) in the gills, liver and tissue of three fresh water fish species (Catfish, Dog fish and Mullet fish) collected from River Niger, Kogi State, Nigeria. The metal concentrations were observed between different organs within each fish species. The highest concentration of Pb (0.7606±0.00 µg/g) was recorded in gill of Catfish, while the lowest value of 0.038±0.0 µg/g) was observed in Catfish liver. Pb was not detected in Catfish tissue and Dog fish liver, respectively. The tissue of mullet fish and dog fish liver accumulated significant higher levels of Cu (0.799±0.0016 µg/g and 0.6866±0.001 µg/g) than other species, while Dog fish tissue accumulated the lowest concentration of Cu (0.0036±0.0001 µg/g). Ni was not detected in all the fish species. The concentration of Zn was found to be higher in Catfish liver (2.4228±0.009 µg/g) and lowest in Dog fish liver with the concentration of 0.4786±0.00 µg/g). The results of this determination therefore, show that metals bioaccumulation in all the fish species except for Catfish gill, did not exceed the permissible limits set for heavy metals in Fish by Food and Agricultural Organisation (FAO) therefore they are safe for human consumption.