What is the form of mercury primarily found in fish?

Methyl mercury is the primary form of mercury that accumulates in fish and is known for its high toxicity to living organisms. It is formed when elemental mercury, which can enter aquatic systems through various environmental processes, is transformed by bacteria in sediment and water into its methylated form. This methyl mercury can then be taken up by microorganisms and subsequently bioaccumulates through the food chain, leading to higher concentrations in larger fish species. This accumulation poses significant health risks to humans who consume contaminated fish, as methyl mercury can affect neurological and developmental health. Thus, in the context of dietary exposure to mercury, methyl mercury stands out as the most relevant concern for fish and human health.