We have heard about the health benefits of fish and we know they are packed with nutrients like omega-3 fatty acids, B vitamins and lean protein. But what about the mercury? What exactly is it and how does it affect you? Which fish have the highest amount? Even I have had trouble keeping up with information, so hopefully I can clarify a few things for you.

  • What is mercury? How do fish get contaminated? 

Mercury occurs in our environment and can be released into the air through industrial pollution, with the highest concentration being from coal-burning power plants. When mercury falls from the air and accumulates in our streams, rivers and oceans, it is converted into methylmercury in the water. Fish and other seafood absorb the methylmercury as they feed in these waters and it builds up in their muscle tissue. The FDA issued its first advisory about methylmercury in seafood in 1994.

  • What are the symptoms of high mercury in human blood?

Methylmercury is a toxin that accumulates in our blood when we eat contaminated seafood, and it mostly affects the nervous system. Symptoms of toxicity include nervousness, irritability, anxiety, emotional instability, insomnia, dizziness, vertigo and many others. Methylmercury can also affect the cardiovascular system, head, neck and oral cavities, and immune systems. For a list of complete symptoms, click HERE.

  • Why is the recommendation to limit fish so strong for pregnant women and children?

Mehtylmercury can be very toxic for a developing fetus, particularly during the first months of pregnancy. It can severely affect the brain and central nervous system, especially in the developing stages of cognitive thinking, memory, attention, language, and fine motor and visual spatial skills. This also applies to infants and young children.

  • What is the current recommendation for women who are pregnant, can become pregnant and children?

The recommendations, according to americanpregnancy.org,  are as follows:


  • Marlin
  • Orange Roughy
  • Tilefish
  • Swordfish
  • Shark
  • Mackerel
  • Tuna (Big eye, Ahi)

Eat no more than three 6-ounce servings per MONTH: HIGH MERCURY

  • Sea Bass (Chilean)
  • Bluefish
  • Grouper
  • Tuna (White albacore, canned)
  • Tuna (Yellowfin)

Eat no more than six 6-ounce servings per MONTH: LOWER MERCURY

  • Bass (Striped, Black)
  • Cod (Alaskan)
  • Halibut (Pacific and Atlantic)
  • Lobster
  • Mahi Mahi
  • Snapper
  • Tuna (canned, chunk light)
  • for entire list, click HERE

Enjoy two 6-ounce servings per WEEK: LOWEST MERCURY

  • Anchovies
  • Crab (domestic)
  • Crawfish/crayfish
  • Oysters
  • Salmon (canned, fresh)
  • Herring
  • Flounder
  • Clams
  • for entire list, click HERE


  • What about woman who are not pregnant, men and others not at high risk?

While the recommendations for caution with high mercury fish are focused on pregnant women and infants, we should all certainly be aware of mercury levels of seafood in general so we can make informed decisions, especially if you eat fish several times a week.

  • What should I do if I have symptoms similar to those in the list above?

You should contact your primary care provider immediately and perhaps suggest a mercury blood test. Treatments vary depending on the cause of the poisoning and include chelating agents to remove methylmercury from the blood.

  • What about sustainability? 

Sustainability refers to making choices that are “ocean-friendly.” The demand for seafood has increased over the last decades, and many fish we enjoy on a regular basis are in trouble due to overfishing or destructive fishing and farming practices. If this is important to you, keep in mind that some of the “LOW mercury” seafood choices may be poor choices in term of sustainability. The best resource to identify sustainable seafood choices is the Monterey Bay Aquarium Seafood Watch, which offers guides specific to different regions of the country.

For a delicious, low mercury recipe, check out my recipe for Grilled Salmon with Korean BBQ Glaze!

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