Don't dump antifreeze down your drain. Contact your county solid waste office for information on proper disposal of anti-freeze. Mercury attaches to particles of organic material or sediment and falls to the river or lake bottom. Bacteria and other microorganisms consume the mercury and convert it to a fat-soluble form. Bacteria that contain mercury are eaten by small animals on the riverbed and the mercury enters their fatty tissues.
Small fish eat the small animals.
Larger fish eat the smaller fish and the mercury builds up in their tissues. The older the fish, the more mercury it contains. If a contaminated fish is eaten by a human, the mercury in the fish is absorbed into human fatty tissues. Although mercury will be eliminated from our bodies over time, frequent meals of contaminated fish will cause accumulation of mercury in human tissue to potentially unsafe levels. No method of cleaning or cooking fish will reduce the amount of mercury in its flesh.