Impact of water pollution with heavy metals on fish health: overview and updates.

Heavy metals (HM) are natural trace components of the aquatic environment, but their levels have been increased due to industrial wastes, geochemical structure, agricultural and mining activities. All these sources of pollution affect the physicochemical characteristics of the water, sediments and biological components, thus negatively affecting the quality and quantity of fish stocks. Environmental pollution is a worldwide problem; heavy metals constitute one of the most important pollutant challenges. The progress of industry has led to increased emission of pollutants into ecosystem. Environmental pollution can cause poisoning, diseases and even death to fish. The absorption and accumulation of different pollutants vary among different biological systems. Therefore, the aims of the present review article are three-way; first to high lighten the impact of the bioaccumulation of heavy metals in different organs of fish and the factors affecting their dissemination. Second, to monitor the biomarkers that is used in the determinations and diagnoses of heavy metal toxicity and pollution. Finally, the role that is played by the histopathological studies on the diagnosis of fish diseases caused the heavy metals.