Mercury in Fish: Which Species Are Safest?

It seems that health professionals are always telling us to eat more fish. Still, most people are aware that some species are too high in mercury, which causes damage to nerves and can lead to memory loss, irritability, and balance problems. In one study carried out in Rhode Island in 2005, 57% of participants stated that they were concerned about the mercury content of seafood.

Mercury Poisoning in Matamata, Japan

In 1953, 121 individuals became ill from mercury poisoning in Matamata, Japan. Twenty-three of the sick were infants and a total of 46 people died. Survivors were left blind, deaf, and with coordination and intellectual deficits. The toxin was traced to contaminated fish in the bay where these individuals lived. Several plants in the area were discharging mercury-containing waste directly into the water that these people relied on for the fish that they ate every day. 

Fish Highest and Lowest in Mercury

Mercury is highest in large predator fish, including tilefish, swordfish, king mackerel, marlin, shark, orange roughy, and bigeye tuna. Albacore tuna contains three times more mercury than canned light tuna. The FDA provides a table containing the mercury content of commercial fish and shellfish (1990-2012).

Fish lowest in mercury include:

  • anchovies
  • Atlantic mackerel
  • catfish
  • cod
  • haddock
  • herring
  • Mahi-mahi
  • pollock
  • salmon
  • sardines
  • shrimp
  • sole
  • tilapia
  • trout

How Much Fish is Safe to Eat?

Women who are pregnant (or could become pregnant) ChildrenEveryone else
albacore tunaNoneNone if under 55 pounds3 oz per week
light tuna2 oz per week1 oz per week12 oz per week
shark, swordfish, king mackerel, and tilefish NoneNone6 oz per week

*Except for pregnant women and children, people can choose amongst three ounces of albacore tuna, 12 ounces of light tuna OR six ounces of the other fish each week.