10 Fish High in Mercury to Avoid
Too much mercury can lead to unintended health consequences.
Updated on December 3, 2025
It’s not just a planet that always seems to be in retrograde — mercury is a naturally occurring heavy metal that you want to avoid getting too much of.
Mercury is found in the Earth’s crust, but we can be exposed to it, often by eating fish and shellfish with high levels of a very toxic form of mercury called methylmercury in their tissues.
Here’s a list of foods that are high in mercury that you may consider avoiding.
What Is Mercury?
Mercury is a neurotoxin, and consuming too much of it can lead to a variety of symptoms, such as:
- Peripheral loss of vision
- Pins and needles feeling in the hands and feet
- Speech impairment
- Trouble hearing or walking
- Muscle weakness
- Loss of motor coordination
People who recently gave birth and are breastfeeding need to be especially careful because mercury can harm the growing brains and nervous systems of infants, which may be more vulnerable to methylmercury than those of adults. When babies are exposed to mercury in the womb, it can also affect their memory, attention, language, fine motor skills, cognitive thinking, and visual-spatial skills.
What Is the Limit for Mercury?
The U.S. Food and Drug Administration (FDA) allows a maximum mercury limit for edible fish at 1 part per million (ppm). Though research suggests that methylmercury levels for most fish are between less than 0.01 ppm and 0.5 ppm.
This amount is purposely 10 times lower than the lowest level linked to health issues such as mercury poisoning, but you should still be careful that your fish intake doesn’t add up throughout the week.
So what foods contain the most mercury? Here are the types of seafood to avoid if you’re watching your mercury intake, ranked by descending ppm count.
1. Tilefish: 1.123 ppm
Tilefish from the Gulf of Mexico is the highest source of mercury, with a mean concentration of 1.123 ppm. This fish is low in fat and has a sweet flavor similar to lobster or crab. However, because it exceeds the FDA’s mercury limit, it is not recommended for consumption, especially for pregnant people, those who are breastfeeding, and children ages 1 through 11 years.
2. Swordfish: 0.995 ppm
Swordfish is another high-mercury offender with 0.995 ppm. People who are pregnant, those trying to get pregnant, and children should completely avoid consuming swordfish.
3. Shark: 0.979 ppm
Shark contains 0.979 ppm of mercury. Because mercury concentration is absorbed by small organisms and works its way up the food chain, its concentration is especially high in large predatory fish like sharks. As such, it is not recommended for people who are pregnant or nursing, those who plan to become pregnant within a year, and children younger than 6 years old.
4. King Mackerel: 0.730 ppm
King mackerel has 0.730 ppm of mercury. However, if you keep your intake to moderate levels (and aren’t pregnant, nursing, or trying to become pregnant), U.S. wild-caught king mackerel can be a smart choice for your seafood because it is sustainably managed and harvested under national regulations.
5. Bigeye Tuna: 0.689 ppm
Bigeye tuna contains 0.689 ppm of mercury. But the high mercury level isn’t the only reason to avoid it. This type of tuna has a vulnerable status due to overfishing in the eastern and western Pacific Ocean. A better option is to opt for canned light tuna, which has only 0.126 ppm of mercury.
6. Orange Roughy: 0.571 ppm
Orange roughy has 0.571 ppm of mercury. However, it’s also not a great eco-friendly pick for your seafood. Orange roughies live extremely long lives (often 200 years or longer) and mature very slowly, so intensive overfishing has significantly decreased populations.
7. Marlin: 0.485 ppm
Marlin contains 0.485 ppm of mercury, and this type of fish often ends up as bycatch of tuna and swordfish longline fisheries, even though they’re rarely targeted by commercial fishers. Although there’s been limited research on marlin populations, the FDA recommends that people who are pregnant or nursing, those who may become pregnant, and young children should avoid marlin.
8. Grouper: 0.448 ppm
Grouper has 0.448 ppm of mercury. If you’re eating grouper, stick to two servings or less per month to remain under the 1 ppm limit of mercury.
9. Chilean Sea Bass: 0.354 ppm
Chilean sea bass contains 0.354 ppm of mercury. It’s important to note that Chilean sea bass is the market name for two species of toothfish that inhabit the cold waters of the Atlantic, Pacific, and Indian Oceans near Antarctica. While this fish has lower levels of mercury than other fish on this list, it’s still important to eat Chilean sea bass in moderation.
10. Halibut: 0.241 ppm
Halibut has 0.241 ppm of mercury. Some types of halibut tend to be higher in mercury than others. For most people, moderate consumption of halibut is safe. But pregnant people or those trying to get pregnant should avoid eating this fish.
The Takeaway
- Consuming high levels of mercury can cause symptoms like peripheral loss of vision, muscle weakness, and trouble speaking, hearing, or walking.
- The FDA has set the limit of how much methylmercury you should consume from seafood to 1 ppm.
- People who are pregnant or nursing, those who are trying to get pregnant, and children should avoid eating any seafood that contains mercury.
- Tilefish has the highest amount of mercury, while fish like Chilean sea bass and halibut contain less mercury and are safer to eat in moderation.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Basic Information About Mercury. U.S. Environmental Protection Agency. December 5, 2024.
- Health Effects of Exposures to Mercury. U.S. Environmental Protection Agency. December 5, 2024.
- Ensle K. Eating Fish Is Healthy: Keeping Environmental and Health Concerns in Perspective. Rutgers. November 2020.
- Mercury Levels in Commercial Fish and Shellfish. U.S. Food and Drug Administration. February 25, 2022.
- Questions & Answers From the FDA/EPA Advice About Eating Fish for Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1 to 11 Years. U.S. Food and Drug Administration. February 17, 2022.
- Fish and Shellfish. National Health Service. December 11, 2023.
- Mercury Guide. National Resources Defense Council. February 14, 2024.
- King Mackerel. National Oceanic and Atmospheric Administration.
- Bigeye Tuna. World Wildlife Fund.
- Hayes M. The Story of the Orange Roughy: A Cautionary Tale for Deep Sea Resource Extraction. The Marine Diaries. March 21, 2021.
- U.S. Department of Commerce and U.S. Department of State. Chilean Sea Bass Frequently Asked Questions. National Oceanic and Atmospheric Administration.
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