6 Types of Fish You Should Avoid Eating Too Often Because of High Mercury Levels

Some popular fish may contain high mercury levels that pose health risks.

Fish is one of the healthiest foods you can include in your diet. It is an excellent source of high-quality protein, omega-3 fatty acids, vitamins, and minerals that support heart, brain, and overall health. However, not all fish are equally safe to eat frequently. Some large predatory species accumulate significantly higher levels of mercury, which may pose health risks if consumed regularly.

Health experts advise that pregnant women, young children, and people with weakened immune systems should be especially cautious when choosing seafood. Understanding which fish tend to contain more mercury can help you make healthier decisions while still enjoying the benefits of seafood.

1. Shark

Sharks are apex predators that feed on many smaller fish throughout their lives. As a result, mercury accumulates in their bodies over time through a process known as bioaccumulation.

High mercury exposure has been associated with neurological problems and may be particularly harmful to developing fetuses and young children.

Better alternative: Salmon or sardines, which provide plenty of omega-3 fatty acids while containing much lower mercury levels.

2. Swordfish

Swordfish is another large predatory fish that often contains elevated mercury concentrations.

Because of its size and long lifespan, mercury continues to build up in its tissues, making frequent consumption less desirable, especially for pregnant women.

Better alternative: Trout or Atlantic mackerel.

3. King Mackerel

Although many varieties of mackerel are nutritious, King Mackerel is known for having relatively high mercury levels.

Regular consumption may increase mercury exposure, which can affect the nervous system over time.

Better alternative: Atlantic or Pacific mackerel, which generally contain much lower mercury levels.

4. Tilefish

Tilefish—particularly those caught in the Gulf of Mexico—are among the fish species with the highest mercury concentrations.

Health authorities often recommend limiting or avoiding these fish for pregnant women and young children because mercury may interfere with healthy brain development.

Better alternative: Cod or haddock.

5. Bigeye Tuna

Tuna remains one of the world's most popular seafood choices, but mercury levels vary significantly between species.

Bigeye tuna generally contains much more mercury than canned light tuna or skipjack tuna.

People who eat tuna frequently should choose lower-mercury varieties whenever possible.

Better alternative: Skipjack tuna or canned light tuna.

6. Orange Roughy

Orange roughy is a deep-sea fish that can live for well over 100 years. Its long lifespan allows mercury to accumulate gradually over decades.

Because of both mercury concerns and sustainability issues, experts often recommend limiting its consumption.

Better alternative: Flounder or sole.

How to Reduce Mercury Exposure While Still Enjoying Seafood

Eating fish remains an important part of a healthy diet. Rather than avoiding seafood altogether, experts recommend choosing species known to have lower mercury levels.

Some practical tips include:

• Choose lower-mercury fish such as salmon, sardines, trout, cod, tilapia, and anchovies.
• Rotate different seafood choices instead of eating the same fish repeatedly.
• Follow local seafood advisories for recreationally caught fish.
• Pregnant women, nursing mothers, and young children should follow national dietary guidelines regarding seafood consumption.

The Bottom Line

Fish offers many important health benefits, but choosing the right species matters. Large, long-lived predatory fish naturally accumulate more mercury than smaller species lower on the food chain.

By selecting lower-mercury alternatives and eating a variety of seafood in moderation, you can continue enjoying the nutritional benefits of fish while reducing unnecessary mercury exposure.

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Some fish naturally contain higher mercury levels than others. Learn which six fish experts recommend limiting and discover healthier, lower-mercury alternatives.