Which fish is low in mercury? A comprehensive guide to safe seafood choices

According to the U.S. Environmental Protection Agency (EPA), high levels of methylmercury can damage the nervous system, especially in young children and developing fetuses. This makes understanding which fish is low in mercury crucial for maintaining a healthy diet.

Quick Summary

This article details which fish are safest to eat due to their low mercury content. It provides a categorized list of best and good choices, a comparison table, and outlines the fish to avoid. Information on how mercury enters the food chain and why smaller, shorter-lived fish are safer options is also included.

Key Points

• Favor Small Fish: Smaller, shorter-lived species like sardines and anchovies are naturally lower in mercury due to less bioaccumulation.

• Choose Shellfish Wisely: Many types of shellfish, including shrimp, clams, and scallops, are excellent low-mercury choices.

• Limit Tuna Consumption: Stick to canned light tuna (skipjack) instead of canned albacore or fresh tuna, as the latter have higher mercury levels.

• Avoid Large Predators: King mackerel, shark, and swordfish are large predatory fish and should be avoided due to very high mercury concentrations.

• Consult Official Guides: The FDA and EPA provide detailed 'Best Choices,' 'Good Choices,' and 'Choices to Avoid' lists for safe seafood consumption.

• Cooking Does Not Remove Mercury: Mercury is bound to the protein in the fish's flesh, so cooking methods cannot reduce the mercury content.

• Vary Your Seafood: Diversifying your fish sources is a simple way to minimize mercury exposure while still enjoying the nutritional benefits of seafood.

Understanding Mercury in Seafood

Mercury is a naturally occurring element that is released into the environment through both natural processes and human activities, such as burning fossil fuels. Once in the water, microorganisms convert it into methylmercury, a highly toxic form that accumulates in the food chain.

The Bioaccumulation Process

This process, known as bioaccumulation, explains why larger, longer-living predatory fish tend to have higher concentrations of mercury than smaller, shorter-lived species. A tuna, for instance, consumes many smaller fish throughout its life. Each of those smaller fish has its own mercury content, which is then added to the tuna's body, compounding the concentration. This is why apex predators like shark, swordfish, and some types of tuna are among the highest in mercury and should be consumed sparingly or avoided entirely by at-risk populations like pregnant women and young children.

Official Guidelines for Safe Consumption

The U.S. Food and Drug Administration (FDA) and the EPA provide joint advice on making safe and healthy fish choices. They categorize fish into three groups based on average mercury levels, offering clear guidance on how often to consume them, especially for those who are pregnant or breastfeeding. Adhering to these guidelines allows you to enjoy the significant health benefits of seafood, such as omega-3 fatty acids, without unnecessary risk.

Best Choices: Fish Low in Mercury

For frequent consumption, focusing on fish from the "Best Choices" list is recommended. These are typically smaller, non-predatory species that accumulate less mercury. The FDA recommends eating 2 to 3 servings (about 8-12 ounces) per week from this category.

• Salmon: Both fresh/frozen and canned salmon are excellent choices with very low mercury levels and are packed with healthy omega-3s.
• Sardines: These small, oily fish are not only low in mercury but also a great source of protein and calcium.
• Anchovies: Tiny and full of flavor, anchovies have minimal mercury content.
• Tilapia: A mild-flavored, farm-raised fish that is consistently low in mercury.
• Catfish: Often farm-raised, catfish is another safe, low-mercury option.
• Shrimp: This popular shellfish has very low mercury levels, making it safe for frequent consumption.
• Scallops: Like shrimp, these shellfish are a very low-mercury option.
• Canned Light Tuna: Made from smaller skipjack or yellowfin tuna, canned light tuna has significantly lower mercury than canned albacore.
• Cod: A flaky whitefish that is a safe and reliable choice.
• Pollock: Often used in fish sticks and fast-food fish sandwiches, pollock is a consistently low-mercury fish.

Good Choices: Moderate Mercury Fish

Fish in the "Good Choices" category can still be part of a healthy diet but should be consumed less often, typically once a week.

• Albacore Tuna (canned/fresh): Albacore, or white tuna, has higher mercury levels than canned light tuna and should be limited.
• Mahi Mahi: Also known as dolphinfish, it has moderate mercury levels.
• Halibut: Both Atlantic and Pacific halibut fall into this category and should be eaten in moderation.
• Grouper: This popular fish has moderate mercury and should be limited to one serving per week.
• Yellowfin Tuna: Fresh or frozen yellowfin contains higher mercury than canned light tuna.

Comparison of Low vs. High Mercury Fish

This table summarizes the mercury risk associated with various fish based on federal guidelines.

Feature	Low Mercury Fish (Best Choices)	High Mercury Fish (Choices to Avoid)
Examples	Salmon, Sardines, Shrimp, Tilapia	King Mackerel, Shark, Swordfish, Bigeye Tuna
Life Span	Shorter	Longer
Size	Smaller	Larger
Diet	Herbivores, small prey	Large predatory fish
Recommended Consumption	2-3 servings per week	Limit or avoid
Special Considerations	Safe for pregnant women and children	Should be avoided by pregnant women and children

What to Consider Beyond Mercury

While mercury is a key concern, it's not the only factor to consider when choosing seafood. For an ethical and environmentally conscious choice, you can check sustainability ratings from organizations like the Monterey Bay Aquarium. This ensures that your seafood is not only safe for your health but also harvested responsibly. Cooking seafood properly is also vital to prevent bacterial infections; however, it's important to remember that cooking does not remove mercury.

Conclusion

Making informed decisions about your seafood consumption allows you to reap the many health benefits of fish while minimizing your exposure to harmful contaminants like mercury. By favoring low-mercury options like salmon, sardines, and tilapia, you can safely enjoy a nutrient-rich diet. Remember the key rule of thumb: smaller, shorter-lived fish lower on the food chain are your safest bet. Always check the latest FDA and EPA guidance for the most current recommendations, especially if you are in a vulnerable group.

Resources

• FDA/EPA Advice on Eating Fish and Shellfish: This is the most comprehensive guide for consumers on making safe seafood choices, with detailed information on mercury levels in various species.
• Mercury Guide from the NRDC: A helpful resource for understanding mercury exposure, especially regarding different types of tuna and sushi.

Low Mercury Seafood List

Here is a quick reference list of safe, low-mercury fish and shellfish:

• Anchovies
• Atlantic mackerel
• Butterfish
• Catfish
• Clam
• Cod
• Crab
• Crawfish
• Flounder
• Haddock
• Hake
• Herring
• Lobster
• Mullet
• Oyster
• Pollock
• Salmon
• Sardine
• Scallop
• Shad
• Shrimp
• Sole
• Squid
• Tilapia
• Trout (freshwater)
• Tuna (canned light)
• Whitefish
• Whiting

By following this advice and incorporating these lower-mercury options into your diet, you can confidently enjoy the nutritional benefits that seafood provides.

Frequently Asked Questions

Which fish has the lowest mercury levels?

Fish with the lowest mercury levels are typically smaller, short-lived species. Some of the safest choices include salmon, sardines, anchovies, scallops, and tilapia.

Which types of fish should be avoided due to high mercury?

Fish to limit or avoid include large predatory species such as king mackerel, shark, swordfish, and bigeye tuna, as they accumulate the highest concentrations of mercury.

Is canned tuna high in mercury?

It depends on the type. Canned light tuna, which is made from smaller skipjack, is considered a 'Best Choice' with low mercury. Canned albacore, or white tuna, has higher levels and should be eaten less frequently, making it a 'Good Choice'.

Is it safe for pregnant women to eat fish?

Yes, it is safe and encouraged for pregnant women to eat fish, but they should select from the low-mercury 'Best Choices' list to get important nutrients like omega-3 fatty acids while minimizing risk.

Do farm-raised fish have lower mercury than wild-caught?

While it varies by species and location, farm-raised fish like tilapia and catfish generally have low mercury levels. Mercury accumulates from the aquatic environment and food chain, so a controlled farming environment can sometimes result in lower concentrations.

Does cooking fish remove mercury?

No, cooking does not remove mercury. The metal is bound to the protein in the fish's flesh, so it will remain whether the fish is prepared raw or cooked.

How often should you eat fish with moderate mercury levels?

Fish with moderate mercury levels, categorized as 'Good Choices' by the FDA, should be limited to about one serving per week for most adults. Examples include halibut and mahi mahi.

Why do larger fish have more mercury?

Larger, older fish tend to have more mercury due to a process called bioaccumulation. As they eat smaller fish throughout their long lives, the mercury from their prey accumulates in their own bodies.