An Essential Guide: Which Seafood Is Lowest in Mercury?

November 3, 2025 •

3 min read

According to the Food and Drug Administration (FDA), nearly all fish contain traces of mercury, but levels vary significantly by species. Navigating which seafood is lowest in mercury is crucial for minimizing health risks while maximizing the benefits of this nutrient-rich food.

Quick Summary

This article explores the mercury content in various types of seafood, offering a comprehensive guide to making safer, more informed dietary choices. It details low-mercury options and explains why certain fish contain higher levels of this heavy metal.

Key Points

Low on the Food Chain: Smaller, shorter-lived seafood like sardines, anchovies, and shellfish contain the least amount of mercury due to bioaccumulation.
Safe 'Best Choices': The FDA recommends eating 2-3 servings per week of low-mercury fish such as salmon, shrimp, tilapia, and cod.
Limit 'Good Choices': Moderately-mercury fish like canned albacore tuna, halibut, and snapper should be consumed only once per week.
Avoid High-Mercury Species: Large predatory fish including shark, swordfish, and king mackerel should be avoided entirely, particularly by pregnant women and young children.
Prioritize Omega-3s: Choosing low-mercury fatty fish like salmon and sardines ensures you receive vital omega-3 fatty acids for brain and heart health without excessive mercury.
Benefit Over Risk: For most people, the health benefits of eating fish outweigh the risks associated with mercury, provided you select lower-mercury varieties.
Farmed vs. Wild: Some research suggests that farmed fish may contain lower mercury levels than their wild-caught counterparts, but the best rule is still to choose smaller species.

The Science of Mercury in Fish

Mercury, a naturally occurring element, enters oceans and lakes through natural events and human activities. Microorganisms transform it into highly toxic methylmercury, which bioaccumulates up the food chain, resulting in higher concentrations in larger, predatory fish like shark and swordfish. Smaller, shorter-lived fish and shellfish generally have lower levels. While most adults can safely consume fish with low to moderate mercury, vulnerable groups like pregnant women and children should be more cautious due to potential developmental risks.

Low-Mercury Seafood Options: The 'Best Choices'

The FDA and Environmental Protection Agency (EPA) offer guidelines, classifying seafood into categories like “Best Choices” that can be eaten two to three times weekly. These choices provide important nutrients such as omega-3 fatty acids, protein, and vitamins essential for development and health.

Some recommended low-mercury options include:

Salmon: Both wild and farmed are low in mercury and rich in omega-3s.
Sardines: Small and low on the food chain, they are packed with omega-3s.
Shrimp: A popular, low-mercury choice.
Scallops: Have extremely low mercury levels.
Oysters: As filter feeders, they contain minimal mercury.
Tilapia: A farm-raised fish that is consistently low in mercury.
Canned Light Tuna: Contains less mercury than albacore and is a “Best Choice”.
Catfish: Another low-mercury option.
Pollock: A reliable low-mercury choice often used in fish products.
Cod: A popular white fish with low mercury.

Considerations for Moderately Sized Fish

Fish in the FDA/EPA's "Good Choices" category, typically larger than "Best Choices" but smaller than high-mercury species, can be eaten about once a week.

Examples of "Good Choices" include Bluefish, Halibut, Mahi Mahi, Snapper, and canned or fresh Albacore Tuna.

Mercury Content Comparison Table

Here is a comparison based on FDA/EPA advisories:


FDA/EPA Category	Examples of Seafood	Typical Mercury Level (PPM)
Best Choices (2-3 servings/week)	Salmon, Sardines, Shrimp, Scallops, Oysters, Tilapia, Canned Light Tuna, Catfish, Pollock, Cod, Anchovies	Very Low (e.g., <0.13)
Good Choices (1 serving/week)	Bluefish, Grouper, Halibut, Mahi Mahi, Snapper, Albacore Tuna	Moderate (e.g., 0.13-0.5)
Choices to Avoid	Shark, Swordfish, King Mackerel, Tilefish (Gulf of Mexico), Bigeye Tuna, Marlin	High (e.g., >0.5)

The Health Benefits of Low-Mercury Seafood

Selecting low-mercury seafood provides significant nutritional benefits without high mercury exposure. Fish is rich in omega-3 fatty acids EPA and DHA, important for cognitive and heart health. For pregnant and nursing women, omega-3s are crucial for fetal development. Many low-mercury fish also offer protein, selenium, iodine, and vitamin D. Choosing smaller, low-mercury species allows frequent, safe consumption of these nutrients.

Conclusion

Making informed seafood choices is vital for health. To minimize mercury exposure, particularly for pregnant individuals and young children, focus on the FDA and EPA's "Best Choices" list. Seafood like salmon, sardines, shrimp, and tilapia consistently have the lowest mercury levels and are packed with nutrients. While high-mercury fish like swordfish should be avoided or limited, many delicious and healthy low-mercury options exist. Understanding bioaccumulation and following official advice ensures seafood is a safe and beneficial part of your diet. For detailed guidance, consult the FDA's Advice about Eating Fish.

Frequently Asked Questions

The lowest mercury species include scallops, sardines, anchovies, shrimp, oysters, tilapia, and canned light (skipjack) tuna. These are generally smaller, shorter-lived organisms lower on the food chain.

Mercury levels in canned tuna depend on the type. Canned light tuna (skipjack) is low in mercury and is a "Best Choice." Canned albacore ("white") tuna has higher mercury content and is considered a "Good Choice," with a recommended limit of one serving per week.

Mercury accumulates in fish through bioaccumulation. Larger, older fish that are higher up the food chain and feed on other fish have more time to accumulate higher concentrations of mercury.

High levels of methylmercury can damage the nervous system. The risk is particularly high for developing fetuses and young children, potentially causing developmental issues. For adults, high exposure can cause neurological and behavioral problems.

Yes, but they should only consume fish from the FDA/EPA's "Best Choices" list, limiting intake to two to three servings per week. Avoiding all high-mercury species is highly recommended for this group.

No, cooking does not significantly reduce the amount of mercury in fish. Methylmercury binds to the muscle tissue and is not easily removed through standard cooking methods.

It's important to check for local fish advisories, which are typically issued by your state or local health department. If no advisory is available, it's safest to limit consumption of locally caught fish.