Which fish has the lowest amount of mercury?

November 20, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA) and Environmental Protection Agency (EPA), small, short-lived fish like sardines and anchovies are among the best choices due to their very low mercury levels. This guide will help you understand which fish has the lowest amount of mercury, allowing for informed and safe dietary decisions.

Quick Summary

This article explains why smaller fish generally contain lower mercury levels due to bioaccumulation. It provides a detailed list of fish and shellfish categorized by mercury content based on FDA/EPA advice, emphasizing safe choices for all consumers, including pregnant women and children. Key insights into dietary recommendations are included.

Key Points

Sardines and Anchovies are the lowest in mercury: As small, short-lived fish, they are among the safest and healthiest choices.
Smaller fish have less mercury: Due to bioaccumulation, smaller fish lower on the food chain contain less mercury than larger predators.
High-mercury fish include King Mackerel and Shark: Large, predatory fish like shark, swordfish, and king mackerel should be avoided, especially by vulnerable groups.
Opt for canned light tuna: When choosing tuna, canned light (skipjack) has significantly less mercury than canned albacore (white) tuna.
Pregnant women and children should be cautious: These groups should stick to the low-mercury "Best Choices" fish and shellfish as recommended by the FDA.
Cooking does not remove mercury: Methylmercury binds to the fish's tissue, so no amount of cooking or preparation will eliminate it.
Seafood offers significant health benefits: It's important to continue eating a variety of low-mercury fish to gain beneficial nutrients like omega-3s, protein, and vitamins.

Understanding Mercury and Bioaccumulation

Mercury, a naturally occurring element, becomes a health concern primarily as methylmercury, a neurotoxin that accumulates in the aquatic food chain. The process, known as bioaccumulation, means that smaller fish consume methylmercury from microorganisms and water. Larger, predatory fish then consume these smaller fish, causing the mercury concentration to increase at each level of the food chain. This is why fish at the top of the food chain, such as shark and king mackerel, have the highest mercury levels. Conversely, smaller fish and shellfish have much lower concentrations, making them safer for frequent consumption.

Factors Influencing Mercury Levels in Fish

Several factors determine the amount of mercury in a specific fish species. The most significant are the fish's lifespan, its position in the food chain (trophic level), and the water body it inhabits. For example, tilefish from the Gulf of Mexico have significantly higher mercury concentrations than Atlantic tilefish. Smaller species that are harvested young tend to have the lowest levels of mercury because they have had less time to accumulate the neurotoxin. Cooking methods, including canning, freezing, or steaming, do not reduce the mercury content in fish.

The Best Choices for Low Mercury Consumption

The FDA and EPA provide extensive guidance on making safe and healthy seafood choices. The "Best Choices" category includes many popular options that can be consumed two to three times per week by most adults and in recommended portions for children and pregnant women. These choices are vital for reaping the benefits of seafood, such as protein, omega-3 fatty acids, and essential vitamins, without undue risk from mercury.

Here is a list of some of the best choices for low-mercury fish and shellfish:

Salmon: Both fresh and canned salmon are excellent low-mercury options, rich in heart-healthy omega-3s.
Sardines: These small, oily fish are very low in mercury and packed with nutrients. They are often sold canned.
Anchovies: Similar to sardines, anchovies are low on the food chain and therefore very low in mercury.
Tilapia: A mild-flavored, farm-raised fish that is consistently low in mercury.
Catfish: Farm-raised catfish is a widely available and safe choice.
Pollock: Often used in fish sticks and fast-food sandwiches, pollock is a low-mercury white fish.
Shrimp: One of the most popular seafood items, shrimp is very low in mercury.
Scallops and Oysters: These shellfish are also among the lowest in mercury.

Low vs. High Mercury Fish Comparison


Feature	Low Mercury Fish (e.g., Sardines, Salmon)	High Mercury Fish (e.g., King Mackerel, Swordfish)
Food Chain Position	Lower on the food chain, consuming smaller organisms.	Higher on the food chain, large predators.
Lifespan	Shorter lifespan, less time to accumulate mercury.	Longer lifespan, more time for mercury accumulation.
Mercury Content	Very low to low, considered safe for frequent consumption.	High, should be consumed sparingly or avoided entirely.
Typical Size	Generally smaller fish.	Generally larger fish.
Nutrient Benefits	Excellent source of omega-3s, protein, and calcium.	Can be a good source of omega-3s, but the high mercury content poses a risk.

Special Considerations for Vulnerable Groups

Pregnant and breastfeeding women, as well as young children, are more susceptible to the harmful effects of methylmercury on the developing nervous system. For these groups, health advisories typically recommend following the strictest guidelines, limiting consumption to the best, low-mercury choices. They should completely avoid fish from the "Choices to Avoid" list, which includes king mackerel, shark, swordfish, and bigeye tuna. For canned tuna, canned light (skipjack) tuna is the lower mercury option compared to canned albacore (white) tuna.

Making Informed Choices

Choosing low-mercury fish doesn't mean sacrificing the nutritional benefits of seafood. Many of the lowest-mercury options, such as salmon, are also among the richest in beneficial omega-3 fatty acids. By prioritizing smaller, shorter-lived species, consumers can enjoy seafood as a regular and healthy part of their diet. Always check for local fish advisories if consuming fish caught recreationally, as mercury levels in local water bodies can vary. For more information on mercury levels and safe consumption, reliable sources include government health agencies and credible environmental organizations like the Natural Resources Defense Council (NRDC).

Conclusion

Sardines and anchovies are the definitive choices for those seeking which fish has the lowest amount of mercury, with shellfish like scallops and shrimp following closely behind. The key principle is that smaller, non-predatory fish have the least accumulation of this neurotoxin. By opting for a variety of these low-mercury options, you can maintain a nutrient-rich diet while minimizing your exposure to harmful heavy metals, ensuring both your health and safety. Always consult guidelines from authoritative sources like the FDA and EPA to stay updated on the latest recommendations.

Disclaimer: The information provided is for general educational purposes and is not a substitute for professional medical advice. Always consult a healthcare provider for personalized dietary recommendations.

Frequently Asked Questions

Larger, predatory fish that live longer tend to have higher concentrations of mercury due to a process called bioaccumulation. Smaller fish that are lower on the food chain accumulate less mercury over their shorter lifespans.

Yes, but it depends on the type. Canned light tuna, which is usually skipjack, is considered a 'Best Choice' with very low mercury levels and is safe for most people, including pregnant women and children, in recommended amounts. Canned albacore ('white') tuna has higher mercury levels and should be limited.

For pregnant women and children, the safest fish are those on the FDA's 'Best Choices' list, which includes salmon, sardines, tilapia, catfish, shrimp, and anchovies. They should avoid high-mercury fish like shark, swordfish, and king mackerel entirely.

No, cooking or any form of preparation, such as canning or freezing, will not reduce the mercury content in fish. The mercury is bound to the fish's muscle tissue and remains even after cooking.

Low-mercury fish provides essential nutrients like omega-3 fatty acids, high-quality protein, and vitamins D and B12. These are crucial for brain function, heart health, and overall well-being.

You should check for local advisories regarding fish caught by family and friends. Mercury levels can vary significantly depending on the specific water body, and local health authorities often issue specific guidance.

Research suggests that some farmed fish, like farmed salmon, may have slightly lower mercury levels than their wild-caught counterparts. However, the best way to minimize exposure is to choose smaller, short-lived species, regardless of whether they are wild or farmed.