Heavy Metals in the Environmental and its effects on fish

The heavy metal concentration in fish tissues reflects past exposure via water and/or food and it can demonstrate the Current situation of the animals before toxicity affects the ecological balance of populations in the aquatic environment. Also, heavy metals are known to induce oxidative stress and/ or carcinogenesis by mediating free radicals/reactive oxygen species. In general, metals can be categorized as biologically essential and non-essential. The nonessential metals (e.g., aluminum (Al), cadmium (Cd), mercury (Hg), tin (Sn) and lead (Pb) have no proven biological function (also called xenobiotics or foreign elements), and their toxicity rises with increasing concentrations [3]. Essential metals (e.g., copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), cobalt (Co), molybdenum (Mo) and iron (Fe)) on the other hand, have a known important biological roles, and toxicity occurs either at metabolic deficiencies or at high concentrations