Some metals are known to be toxic even at low concentrations, including chromium, lead,
cadmium, arsine and mercury (Nguyen et al 2005). While others, such as copper, iron, zinc,
manganese and cobalt, are known to be essential elements and play important roles in biological
metabolism at very low concentrations and either and excess or deficit can disturb biochemical
functions in both humans and animals (Yilden, 2003). Heavy metals, unlike organic pollutants,
cannot be chemically degraded or biodegraded by microorganisms. Thus, their content has
steadily increased in water and subsequently accumulated in sediments, plants, fishes, and even
in humans ( Che et. al, 2006). Heavy metals pollutants after entering into aquatic environment
accumulate in tissues and organs of aquatic organisms. Inputs of heavy metals into the soils and
water have gradually increased over the past decades as a consequence of anthropogenic
activities. Unlike energy which tend to deplete and becomes dispersed at each trophic level,
heavy metals become more concentrated with each trophic level in the food chain. Egunjobi and
Adesina (2002) reported that concentration of heavy metal become enhanced with progression