The FDA set a limit for mercury in fish, but what does it mean?
Mercury levels for most fish range from non-detectable to 0.5 parts per
million (ppm). In a few species, mercury levels can reach 1 ppm, the
limit the U.S. Food and Drug Administration (FDA) suggests for fish
intended for human consumption. However, the average concentration in
the 10 most popular commercial species is 0.12 ppm or about 8 times
lower than the FDA limit. http://www.aboutseafood.com/media/top_10.cfm
