Metals Concentrations in Tissues of Tilapia gallier, Crarias lazera and Osteoglossidae Caught from Alau Dam, Maiduguri, Borno State, Nigeria

An analysis of intestine, liver, stomach and gill tissue concentrations of heavy metals (Cu, Co, Pb, Cr, Mn, Fe, Ni, Cd and Zn) in three commercially important fish species (Tilapia gallier, Crarias lazera and Osteoglossidae. caught within Alau Dam between the periods of January to August, 2007. These heavy metals were determined using Perkin-Elmer AAnalyst 300 Atomic Absorption Spectroscopy (AAS). Heavy metals contents varied significantly (p>0.05) depending on the fish species and on the types of tissues. The concentration of heavy metals in livers and gills tissue were relatively higher than the intestine and stomach tissues of the three species. The distribution of copper and cobalt were in the order of gills>stomach>liver>intestine in the entire fish samples, while the distribution of (Pb, Cr, Mn, Fe, Ni, Cd and Zn) were in the order of liver>gills>stomach>intestine. The concentrations of the entire elements in the three species were within tolerance limits that are safe for human consumption, with exception of lead in gills.