Bioaccumulation of Heavy Metals in Fishes of Hashenge Lake, Tigray, Northern Highlands of Ethiopia

Water samples, bottom sediments, Oreochromis niloticus (Nile Tilapia), and Cyprinus carpio(Common Carp) from Lake Hashenge, Tigray, Northern Ethiopia were analysed quantitatively for the presence of copper, iron, zinc, cobalt, lead, nickel, chromium, manganese and cadmium using Atomic Absorption Spectrophotometer. The concentrations of 9 elements in Tilapia flesh, Tilapia bone, Common Carp flesh and Common carp bone (mg element/kg dry mass) were: Cu 0.85, 2.33, 1.40, 3.37; Pb 1.24, 0.88, 1.24, 1.11; Cr 0.37, 3.02, 0.65, 3.65; Cd 0.58, 1.62, 0.53, 1.66; Mn 1.01, 6.27, 1.79, 12.53; Co 1.61, 6.09, 1.50, 5.77; Fe 64.87, 134.75, 49.59, 99.53; Ni 0.41, 0.47, 0.36, 0.53 and Zn 24.95, 105.57, 46.08, 153.90, respectively. Studies on the different parts of the fish revealed higher concentrations of heavy metals on the bones than flesh parts of both the Nile Tilapia and Common Carp fishes. In most of the fish samples, lead, chromium, cadmium, cobalt and zinc concentration were found to be above the maximum tolerable values provided by FAO/WHO (1989). Results also revealed organ specific distribution of heavy metals in Common Carp and Nile Tilapia, which has been due to the physiological role in fish and/or the likely influence of natural and anthropogenic sources on Hashenge Lake.