Introduction: Mercury (Hg) is a pollutant on a global scale; its emission spreads over long distances in the atmosphere and across the oceans. Mercury is released into the environment from a multitude of natural and anthropogenic sources. The presence and behavior of Hg in aquatic systems is of great interest and importance. Bacteria in lakes and ocean sediment can convert element and inorganic Hg into its organic compound (methyl), which may accumulate in algae, aquatic plants and fish and into the food chain. The poisoning characteristic of mercury causes many problems, including: neurological symptoms, reproductive disorders, circulatory diseases and digestive disorders. The presence of Hg in living organisms is undesirable and potentially hazardous.