Concentrations of heavy metals (HMs - Pb, Mn, Fe, Cu and Cd) in water and sediments, and their bioaccumulations in gill and muscle tissues of Clarias gariepinus from four earthen fish ponds in communities around Kolo Creek area of Bayelsa State, Nigeria, were evaluated. The HMs were extracted with acid mixtures, quantified using atomic absorption spectrophotometry and characterized in terms of metal pollution index (MPI). Furthermore, pond waters’ physicochemical properties were determined using standard methods. The pH values of pond waters indicated slight alkalinity. Biochemical oxygen demand indicated significant pollution of the ponds. Range of HMs concentrations are: water (mg/L) – Fe: 0.013 - 0.30, Cu: 0.002 - 0.96; Mn: 0.20 - 0.83; Pb: 0.01 - 0.15, Zn: 0.67 - 2.72; sediment (mg/kg) – Fe: 67.8 - 200.3, Cu: 0.98 - 2.95; Mn: 4.06 - 17.1; Pb: 0.73 - 10.6, Zn: 1.90 - 96.9 and tissues (mg/kg) – Fe: 0.001-1.97, Cu: 0.98-17.2, Mn: 0.001-33.9, Pb: 0.001-8.13, Zn: 0.16-36.9. All HMs in pond waters were below drinking water limits except Pb and Mn. Gills and muscles showed high Fe and Pb concentrations respectively. The MPI values revealed that the bioaccumulation capacity of a fish tissue for HMs depended on several factors. The results generally suggest significant HMs bioaccumulation in tissues of Clarias gariepinus, which can be risky to consumers over time.
