What fish has the least mercury in it?

January 8, 2026 •

4 min read

According to the U.S. Food and Drug Administration (FDA), nearly all fish contain traces of methylmercury, but levels vary significantly by species. This makes understanding what fish has the least mercury in it essential for making safer dietary choices for you and your family.

Quick Summary

Smaller, shorter-lived fish like sardines, salmon, and anchovies typically have the lowest mercury content. Factors like diet and lifespan influence mercury accumulation.

Key Points

Smaller fish have less mercury: Smaller, non-predatory species like sardines, shrimp, and anchovies have the lowest mercury content due to their position on the food chain.
Salmon is a safe choice: Both fresh and canned salmon are excellent, low-mercury sources of healthy omega-3 fatty acids.
Avoid large predatory fish: Species such as shark, swordfish, and king mackerel accumulate high levels of mercury and should be avoided, especially by sensitive populations.
Canned tuna varies by type: Canned light tuna (skipjack) is a better low-mercury option than canned albacore (white) tuna.
Cooking doesn't remove mercury: Mercury is bound to proteins in the fish's muscle and cannot be eliminated through cooking methods like frying or boiling.
Advisories exist for local catches: If you eat locally caught fish, check with local health departments for specific advisories, as regional mercury levels can differ.
Prioritize variety and moderation: Eating a variety of low-mercury seafood and following recommended consumption guidelines helps maximize health benefits while minimizing risk.

Understanding Mercury in Seafood

Methylmercury is a neurotoxin that can accumulate in the human body over time. It enters our waterways primarily through industrial pollution and naturally occurring sources. From there, tiny organisms absorb it, which are then eaten by small fish. This process of bioaccumulation means that larger, predatory fish higher up the food chain accumulate higher concentrations of mercury by consuming many smaller, mercury-containing fish. This biological reality dictates why certain fish are safer to eat more frequently than others.

Factors Influencing Mercury Levels

Several factors contribute to the mercury concentration in a fish. As mentioned, a fish's position on the food chain is the most critical factor. Size and age are also significant, as larger, older fish have had more time to accumulate the toxin. The environment and diet also play a role, with some wild-caught fish from certain areas having different levels than their farmed counterparts. For instance, a study mentioned that mercury levels were lower in some farmed fish than wild-caught. However, the general rule of thumb is that smaller, non-predatory fish are the best low-mercury options.

The Safest Low-Mercury Seafood Choices

The FDA and EPA have issued clear guidelines on which seafood options fall into the 'Best Choices' category, representing the fish with the least mercury. These include a variety of fish and shellfish that are rich in beneficial omega-3 fatty acids and other essential nutrients, making them a cornerstone of a healthy diet.

Best Choices for Low Mercury Consumption

Here is a list of some of the best low-mercury fish and shellfish, which can be eaten two to three times per week by most adults:

Salmon: An excellent source of omega-3s, both canned and fresh/frozen salmon have very low mercury levels.
Sardines: These small, oily fish are very low in mercury and high in protein and omega-3s.
Shrimp: Among the seafood with the lowest mercury content, shrimp is a safe and popular choice.
Anchovies: Tiny and full of flavor, anchovies are very low in mercury.
Tilapia: Often farmed, this white fish is a consistently low-mercury option.
Cod: A flaky, versatile white fish with low mercury levels.
Catfish: Especially farm-raised catfish, which has lower mercury levels than some wild-caught varieties.
Scallops: These shellfish are among the lowest in mercury of all seafood.
Oysters and Clams: As bivalves, they are filter feeders low on the food chain and contain very little mercury.

Higher Mercury and Moderate Choices

Some popular fish, while still nutritious, contain moderate mercury levels and should be eaten in smaller quantities, usually limited to one serving per week for pregnant women and children. Conversely, large predatory fish should be avoided by vulnerable groups due to their significantly higher mercury content.

Mercury Levels in Popular Fish Species


Fish Species	Average Mercury Level (PPM)	FDA Consumption Advisory	Notes
Scallops	0.003	Best Choice	Extremely low mercury.
Shrimp	0.009	Best Choice	Very low mercury.
Sardines	0.013	Best Choice	Very low mercury, high omega-3.
Salmon	0.022	Best Choice	Low mercury, high omega-3.
Catfish	0.025	Best Choice	Farmed is a safe option.
Pollock	0.031	Best Choice	Low mercury.
Atlantic Mackerel	0.050	Best Choice	Low mercury.
Cod	0.111	Best Choice	Low mercury.
Canned Light Tuna	0.126	Best Choice	Moderate levels, widely available.
Canned Albacore Tuna	0.350	Good Choice	Higher than light tuna, limit intake.
Swordfish	0.995	Choice to Avoid	Very high mercury levels.
Shark	0.979	Choice to Avoid	Very high mercury levels.
King Mackerel	0.730	Choice to Avoid	High mercury levels.

Making Informed Choices

Choosing your seafood wisely is a matter of weighing nutritional benefits against potential mercury exposure. The FDA's advice provides a robust framework for making these decisions, especially for sensitive populations like pregnant women and young children. A variety of low-mercury options, from salmon to shellfish, ensures you can enjoy seafood's health benefits without excessive risk. When sourcing fish, it's also prudent to check for local advisories, as mercury levels in locally caught fish can differ from averages. You can find more specific guidance on the FDA's website regarding fish consumption advisories.

Conclusion: Prioritizing Safe and Nutritious Seafood

In conclusion, the question of what fish has the least mercury in it is best answered by looking to smaller, non-predatory species. Shrimp, sardines, salmon, and tilapia are consistently safe choices with minimal mercury accumulation. By understanding the principle of bioaccumulation and following advisories from health authorities like the FDA, consumers can confidently navigate the seafood market. Incorporating a variety of low-mercury fish into your diet ensures you reap the significant nutritional benefits, particularly essential omega-3 fatty acids, while minimizing exposure to harmful contaminants. Regular consumption of these safe options, balanced with moderation, is the most effective strategy for a healthy diet that includes fish.

Frequently Asked Questions

Fish with the highest mercury levels are large, predatory species like shark, swordfish, king mackerel, and tilefish from the Gulf of Mexico. These fish are at the top of the marine food chain and accumulate the most mercury over their longer lifespans.

The mercury level in canned tuna depends on the type. Canned light tuna, which is typically made from skipjack, is lower in mercury and categorized as a 'Best Choice'. Canned albacore ('white') tuna has higher mercury levels and is considered a 'Good Choice', with consumption limits advised.

No, cooking does not remove mercury from fish. Mercury is bound to the protein in the fish's muscle tissue, so methods like frying, grilling, or poaching do not reduce its concentration.

Generally, yes. Some research indicates that farmed fish, like farmed salmon and catfish, may have lower mercury levels than their wild-caught counterparts. This is because their diet is more controlled and they live in monitored environments.

Women who are or may become pregnant, nursing mothers, and young children are the most vulnerable to the harmful effects of methylmercury, which can impact a baby's developing nervous system.

Mercury builds up in fish through a process called bioaccumulation. It starts with plankton absorbing methylmercury from the water, which is then consumed by small fish. As larger fish eat these smaller fish, the mercury accumulates in higher concentrations up the food chain.

For most people, health organizations recommend eating two to three servings of a variety of low-mercury fish per week. For those at higher risk, like pregnant women, specific guidelines on portion size and frequency apply.

Methylmercury is the organic form of mercury that builds up in fish, while elemental mercury is a separate form found in other products. It is the methylmercury in fish that is harmful when consumed.

Local advisories are important because mercury levels can vary in specific bodies of water. If you eat fish caught by friends or family, check with your local health department for specific recommendations before consuming.