Abstract

Akwa Ibom State is located in the Niger Delta region of Nigeria and a substantial amount of the fishes consumed in the area are bought at Ifiayong and Ibaka beaches. This study was carried out to analyze heavy metals (Zn, Cu, Cd, Pb, Cr and As) in kidney, heart, gills and liver of silver catfish (Chrysichthys nigrodigitatus) from these locations. Analysis was performed using Atomic Absorption Spectrophotometry (AAS). The results show that the levels of Zn and Cu were significantly higher than maximum recommended levels (p<0.05) at both locations and were significantly higher in Ifiayong than Ibaka in all the organs (p<0.05). Concentrations of Pb, As, Cr and Cd were significantly higher (P <0.05) in Ibaka than Ifiayong in all the organs of fish analyzed. The order of accumulation of metals in the organs were as follows; Ibaka: heart/gills: Zn > Cu > Cr > Pb > As > Cd; kidney: Zn > Cu > Cr > Pb > Cd > As; liver: Zn> Cu > Cr > As >Pb > Cd. Ifiayong: gills/heart: Zn> Cu > Cr > Pb > Cd > As; kidney: Zn > Cu > Cr > As > Cd = Pb and Liver: Zn > Cu > Cr > Pb > Cd = As. In general, these results show that the levels of Zn, Cu, Pb, Cr and As in the fish bought at Ibaka were above recommended levels while those bought at Ifiayong (with the exception of Zn and Cu) were significantly lower (p<0.05) than standards set by WHO/FAO/UNEP. This study, therefore, suggests the need for regular monitoring and assessment of fishing sites in this region for heavy metal contamination to protect the health of consumers.

Key words: Chrysichthys nigrodigitatus, heavy metals, Ibaka, Ifiayong, Niger Delta region, silver catfish.