The Best Types of Fish to Avoid Mercury

How to Choose Safer Seafood


Verywell / Alexandra Shytsman

Fish may be an anti-aging superfood, but eating the wrong kinds of fish too often can raise the level of mercury in your body. This is especially dangerous for pregnant and breastfeeding women because fetuses and newborns are very sensitive to mercury. Find out the best fish to eat and in what amounts.


All fish contain trace amounts of mercury. For most people, the small amounts in fish do not pose a health problem. Some fish, however, contain high amounts of mercury—enough to damage a fetus or newborn. That is why pregnant and nursing mothers must be very careful about the amounts and types of fish they eat. Young children should also avoid eating fish high in mercury.

According to the FDA, pregnant women and small children (under age 6) should not eat more than two servings of fish each week—and should only eat those fish with low mercury content.

Mercury levels can build in adults too—eventually becoming harmful to health. High mercury levels can cause permanent damage to the kidneys and brain. Mercury is naturally eliminated from your body, but it can take several months for it to pass through. For that reason, women who are planning to become pregnant may want to begin to avoid fish that are higher in mercury before they become pregnant.

How Fish Get Contaminated

The mercury found in fish is methylmercury. First, mercury is released into the air and then settles onto the land and into the water. Bacteria and other microorganisms convert the mercury into methylmercury. Then, fish and shellfish in the water begin to absorb it. Fish that eat other fish and who live longer have higher levels of methylmercury.

Effects on Humans

Methylmercury is toxic to the central nervous system—the brain and spinal cord. It causes irreversible damage. The brains of unborn babies and infants are especially susceptible. How much damage is done depends on how much you are exposed to the chemical.

The effects of methylmercury poisoning include cerebral palsy, blindness, deafness, impaired mental functioning, impaired lung function, growth problems, and having a small head.

Mercury Levels in Fish

Large fish have more mercury for the simple reason that big fish usually live longer. They have more time to build up higher levels of mercury in their bodies. See the lists below for general mercury levels of many common types of fish and how much of each type to eat (according to the National Resource Defense Council).

The Environmental Protection Agency (EPA) recommends checking local advisories for the mercury content of fish caught in your area using their website.

Low Levels

Herring. Verywell / Alexandra Shytsman

Eat two to three servings a week of the following fish (pregnant women and small children should not eat more than 12 ounces or two servings):

  • Anchovies
  • Catfish
  • Clam
  • Crab
  • Crawfish
  • Croaker (Atlantic)
  • Flounder
  • Haddock
  • Hake
  • Herring
  • Mackerel (North Atlantic, Chub)
  • Mullet
  • Oyster
  • Perch (The FDA lists this on the low list, but the NDRC lists it as moderate or high)
  • Pollock
  • Salmon
  • Sardine
  • Scallop
  • Shrimp
  • Sole
  • Squid
  • Tilapia
  • Trout
  • Whitefish

Moderate Levels

Halibut. Verywell / Alexandra Shytsman

Eat six servings or fewer per month (pregnant women and small children should avoid these):

  • Bass (Saltwater, Striped, Black)
  • Buffalofish
  • Carp
  • Cod (Alaskan)
  • Halibut
  • Lobster
  • Mahi Mahi
  • Monkfish
  • Perch (freshwater)
  • Snapper
  • Skate
  • Tilefish (Atlantic)
  • Tuna (canned chunk light)

High Levels

Mackerel. Verywell / Alexandra Shytsman

Eat three servings or less per month (pregnant women and small children should avoid these):

  • Bluefish
  • Grouper
  • Sea Bass (Chilean)
  • Mackerel (Spanish, Gulf)
  • Croaker (White, Pacific)
  • Sablefish
  • Perch (ocean)
  • Tuna (canned albacore, yellowfin)

Highest Levels

The FDA lists these choices to avoid eating:

  • Bluefish and grouper: The National Resources Defense Council adds these to the list of those to avoid.
  • King mackerel
  • Marlin
  • Orange Roughy
  • Shark
  • Swordfish
  • Tilefish (from the Gulf of Mexico)
  • Tuna (Bigeye, Ahi)

A Word From Verywell

Fish can be part of a healthy diet, but it is wise to choose fish that will be lower in mercury. Explore recipes for fish, including these using seafood from the low-mercury list:

Enjoy this great source of protein and omega-3 fatty acids. In fact, many long-lived peoples around the world have a diet rich in fish and seafood.

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Article Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. Food and Drug Administration. Advice about Eating Fish.

  2. World Health Organization. Mercury and Health.

  3. U.S. Food and Drug Administration. Questions & Answers from the FDA/EPA Advice about Eating Fish for Women Who Are or Might Become Pregnant, Breastfeeding Mothers, and Young Children.

  4. Rice KM, Walker EM, Wu M, Gillette C, Blough ER. Environmental mercury and its toxic effects. J Prev Med Public Health. 2014;47(2):74-83. doi:10.3961/jpmph.2014.47.2.74

  5. National Resource Defense Council. The Smart Seafood Buying Guide.

  6. Cannella C, Savina C, Donini LM. Nutrition, longevity and behavior. Arch Gerontol Geriatr. 2009;49 Suppl 1:19-27. doi:10.1016/j.archger.2009.09.008

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