What Fish Has the Least Amount of Toxins? A Guide to Safe Seafood Choices

Nearly all fish contain trace amounts of contaminants like methylmercury, but most varieties have levels that are safe for regular consumption. The key to minimizing risk while maximizing benefits, like healthy omega-3 fatty acids, is knowing which fish has the least amount of toxins.

Quick Summary

Smaller, shorter-lived fish like salmon, sardines, and tilapia consistently have the lowest levels of toxins, including mercury. This allows for regular consumption, maximizing the nutritional benefits while significantly minimizing health risks.

Key Points

• Choose small, short-lived fish: Species like sardines, anchovies, and tilapia accumulate fewer toxins like mercury due to their shorter life spans.

• Favor wild-caught Alaskan salmon: This variety is a top choice for healthy omega-3s with low mercury and is often managed for sustainability.

• Be cautious with canned tuna: Opt for canned 'light' (skipjack) tuna over 'white' (albacore), which has significantly more mercury.

• Avoid large, predatory fish: Shark, swordfish, and king mackerel are at the top of the food chain and have the highest toxin levels.

• Vary your fish intake: Eating a wide variety of low-toxin fish and shellfish reduces your exposure to any single contaminant.

• Check local water advisories: When eating recreationally caught fish, consult local health guidelines as contaminant levels can vary by location.

• Prepare fish properly: Trimming fat from fish before cooking and choosing cooking methods that drain fat can reduce exposure to certain POPs.

Understanding Contaminants in Seafood

Fish is an excellent source of protein, vitamins, and heart-healthy omega-3 fatty acids. However, concerns over toxins have led many people to question their seafood consumption. The primary contaminants found in fish are methylmercury and persistent organic pollutants (POPs), such as PCBs and dioxins. The level of these toxins varies significantly between different species of fish, with larger, older, and more predatory fish typically accumulating higher concentrations through a process known as biomagnification. By choosing wisely, you can enjoy the many health benefits of fish without excessive exposure to these harmful substances.

How Mercury Accumulates in Fish

Mercury is a naturally occurring element that is also released into the atmosphere through industrial pollution. In water, microorganisms convert this element into methylmercury, which is then absorbed by small aquatic organisms. As small fish consume these organisms, and then larger fish consume the smaller fish, the concentration of methylmercury increases at each step of the food chain, a process called biomagnification. Consequently, large, long-lived predators like shark and swordfish have the highest mercury levels, while small, short-lived fish accumulate far less.

The Healthiest and Safest Fish Choices

The safest fish to eat are those that are low on the food chain and grow relatively quickly, minimizing their exposure to environmental contaminants. The FDA and EPA have compiled comprehensive lists to help consumers make informed decisions.

Best Choices (Lowest Toxin Levels):

• Salmon: Both wild-caught Alaskan and sustainably farmed varieties are excellent sources of omega-3s and have low mercury levels.
• Sardines and Anchovies: These small, oily fish are very low in mercury and packed with omega-3s and calcium.
• Tilapia: Farmed tilapia is low in mercury and a lean protein source.
• Catfish: US-farmed catfish contains very low levels of mercury.
• Cod: A flaky whitefish that is low in fat and mercury.
• Pollock: Often used in products like fish sticks, pollock is a lean, low-mercury option.
• Shrimp and Scallops: Shellfish like shrimp and scallops are among the lowest in mercury.
• Canned Light Tuna: Typically made from smaller, faster-growing skipjack tuna, it is a “best choice” with less mercury than albacore.

Fish to Eat in Moderation

Some fish offer nutritional benefits but have moderate levels of contaminants, requiring more mindful consumption, especially for sensitive groups like pregnant women and young children. The FDA recommends limiting these to one serving per week.

Good Choices (Moderate Toxin Levels):

• Albacore Tuna: Also known as 'white tuna', it is larger and contains more mercury than canned light tuna, so it should be consumed less frequently.
• Mahi Mahi: This fish falls into the mid-range for mercury content and can be enjoyed in moderation.
• Grouper and Halibut: These larger fish accumulate moderate levels of mercury.

Fish to Limit or Avoid

Large, predatory fish that live for a long time are at the top of the food chain and contain the highest levels of methylmercury. The FDA advises pregnant women, breastfeeding women, and young children to avoid these entirely, while others should consume them rarely, if at all.

Choices to Avoid (Highest Toxin Levels):

• Shark
• Swordfish
• King Mackerel
• Marlin
• Tilefish (Gulf of Mexico)
• Bigeye Tuna
• Orange Roughy

Comparison of Fish Toxin Levels

Fish Category	Examples	Average Mercury (ppm)	Consumption Advice	Key Characteristics
Best Choices	Salmon, Sardines, Tilapia, Cod, Shrimp, Canned Light Tuna	Very Low (< 0.05)	2-3 servings per week	Smaller, shorter-lived species with quick life cycles. Low on the food chain.
Good Choices	Albacore Tuna, Mahi Mahi, Halibut, Grouper	Moderate (0.05-0.5)	Limit to 1 serving per week for most adults.	Larger fish that live longer than "Best Choices" but are not apex predators.
Choices to Avoid	Shark, Swordfish, King Mackerel, Bigeye Tuna	High (> 0.5)	Avoid for at-risk groups; limit for all others.	Apex predators that are large and long-lived, leading to high bioaccumulation.

Additional Tips for Minimizing Risk

1. Vary Your Seafood: Diversifying your seafood intake is one of the best strategies. By eating a mix of different fish and shellfish, you reduce your exposure to any single type of contaminant and get a wider range of nutrients.
2. Check Local Advisories: If you consume fish caught recreationally from local lakes, rivers, or coastal areas, check for local advisories from your health department. Contaminant levels can vary significantly by location.
3. Trim and Cook Properly: For fatty fish that may contain pollutants like PCBs in their fat, you can further reduce exposure by trimming the fat before cooking and using cooking methods that allow the fat to drip away, such as grilling or broiling.
4. Consider Farmed Fish: While some farmed fish have received criticism, farmed freshwater fish like trout and catfish are among the safest choices with very low contaminant levels.

Conclusion

While toxins like mercury and PCBs are a valid concern, they should not be a reason to avoid eating fish altogether. The nutritional benefits, particularly from omega-3 fatty acids, are substantial and critical for heart and brain health. The key is to be a selective consumer by focusing on smaller, shorter-lived fish that are lower on the food chain. By choosing varieties like salmon, sardines, and canned light tuna, you can confidently include seafood in your diet and enjoy its many health-promoting properties. Always follow guidelines from reputable sources like the FDA to ensure a safe and healthy eating pattern. For comprehensive seafood advice, consult the official FDA guide to eating fish.

Understanding Contaminants in Seafood

Fish is an excellent source of protein, vitamins, and heart-healthy omega-3 fatty acids. However, concerns over toxins have led many people to question their seafood consumption. The primary contaminants found in fish are methylmercury and persistent organic pollutants (POPs), such as PCBs and dioxins. The level of these toxins varies significantly between different species of fish, with larger, older, and more predatory fish typically accumulating higher concentrations through a process known as biomagnification. By choosing wisely, you can enjoy the many health benefits of fish without excessive exposure to these harmful substances.

How Mercury Accumulates in Fish

Mercury is a naturally occurring element that is also released into the atmosphere through industrial pollution. In water, microorganisms convert this element into methylmercury, which is then absorbed by small aquatic organisms. As small fish consume these organisms, and then larger fish consume the smaller fish, the concentration of methylmercury increases at each step of the food chain, a process called biomagnification. Consequently, large, long-lived predators like shark and swordfish have the highest mercury levels, while small, short-lived fish accumulate far less.

The Best "Low Toxin" Fish Choices

The safest fish to eat are those that are low on the food chain and grow relatively quickly, minimizing their exposure to environmental contaminants. The FDA and EPA have compiled comprehensive lists to help consumers make informed decisions.

Best Choices (Lowest Toxin Levels):

• Salmon: Both wild-caught Alaskan and sustainably farmed varieties are excellent sources of omega-3s and have low mercury levels.
• Sardines and Anchovies: These small, oily fish are very low in mercury and packed with omega-3s and calcium.
• Tilapia: Farmed tilapia is low in mercury and a lean protein source.
• Catfish: US-farmed catfish contains very low levels of mercury.
• Cod: A flaky whitefish that is low in fat and mercury.
• Pollock: Often used in products like fish sticks, pollock is a lean, low-mercury option.
• Shrimp and Scallops: Shellfish like shrimp and scallops are among the lowest in mercury.
• Canned Light Tuna: Typically made from smaller, faster-growing skipjack tuna, it is a “best choice” with less mercury than albacore.

Fish to Eat in Moderation

Some fish offer nutritional benefits but have moderate levels of contaminants, requiring more mindful consumption, especially for sensitive groups like pregnant women and young children. The FDA recommends limiting these to one serving per week.

Good Choices (Moderate Toxin Levels):

• Albacore Tuna: Also known as 'white tuna', it is larger and contains more mercury than canned light tuna, so it should be consumed less frequently.
• Mahi Mahi: This fish falls into the mid-range for mercury content and can be enjoyed in moderation.
• Grouper and Halibut: These larger fish accumulate moderate levels of mercury.

Fish to Limit or Avoid

Large, predatory fish that live for a long time are at the top of the food chain and contain the highest levels of methylmercury. The FDA advises pregnant women, breastfeeding women, and young children to avoid these entirely, while others should consume them rarely, if at all.

Choices to Avoid (Highest Toxin Levels):

• Shark
• Swordfish
• King Mackerel
• Marlin
• Tilefish (Gulf of Mexico)
• Bigeye Tuna
• Orange Roughy

How to Reduce Toxin Exposure Further

Beyond choosing low-toxin species, you can take additional steps to reduce your intake of contaminants from seafood:

• Vary Your Seafood: Diversifying your seafood intake is one of the best strategies. By eating a mix of different fish and shellfish, you reduce your exposure to any single type of contaminant and get a wider range of nutrients.
• Check Local Advisories: If you consume fish caught recreationally from local lakes, rivers, or coastal areas, check for local advisories from your health department. Contaminant levels can vary significantly by location.
• Trim and Cook Properly: For fatty fish that may contain pollutants like PCBs in their fat, you can further reduce exposure by trimming the fat before cooking and using cooking methods that allow the fat to drip away, such as grilling or broiling.
• Consider Farmed Fish: While some farmed fish have received criticism, farmed freshwater fish like trout and catfish are among the safest choices with very low contaminant levels.

Conclusion

While toxins like mercury and PCBs are a valid concern, they should not be a reason to avoid eating fish altogether. The nutritional benefits, particularly from omega-3 fatty acids, are substantial and critical for heart and brain health. The key is to be a selective consumer by focusing on smaller, shorter-lived fish that are lower on the food chain. By choosing varieties like salmon, sardines, and canned light tuna, you can confidently include seafood in your diet and enjoy its many health-promoting properties. Always follow guidelines from reputable sources like the FDA to ensure a safe and healthy eating pattern. For comprehensive seafood advice, consult the official FDA guide to eating fish.

Frequently Asked Questions

Which specific fish species are considered the absolute safest to eat due to low toxin levels?

The safest fish to eat include anchovies, sardines, salmon (especially wild Alaskan), tilapia, freshwater trout, catfish, and shellfish like shrimp and scallops. These species are low on the food chain and short-lived, minimizing toxin accumulation.

Is all canned tuna high in mercury?

No, not all canned tuna is high in mercury. Canned 'light' tuna, which is usually skipjack, has much lower mercury levels than canned 'white' or albacore tuna. The FDA considers canned light tuna a 'best choice' for consumption.

Why do larger fish tend to have more toxins?

Larger, predatory fish have more toxins due to biomagnification. As these fish eat smaller fish over their longer lifespans, mercury and other contaminants accumulate in their bodies at higher concentrations.

Should pregnant women or young children avoid all fish?

No, pregnant women, nursing mothers, and young children should not avoid all fish. They should, however, specifically avoid high-mercury fish like shark and swordfish, and instead focus on low-mercury options like salmon and shrimp, which provide crucial omega-3 fatty acids for brain development.

Does eating farmed fish expose me to more toxins?

Not necessarily. The toxin levels in farmed fish can vary depending on the farming practices. Some farmed freshwater fish, like trout and catfish raised in controlled environments, have consistently low levels of contaminants and are considered safe choices.

Besides mercury, what other toxins are found in fish?

In addition to methylmercury, fish can contain persistent organic pollutants (POPs) such as PCBs and dioxins. These fat-soluble toxins can be further reduced by trimming the fat from fish and choosing appropriate cooking methods.

What is the best way to choose seafood from a sustainability standpoint?

To choose seafood sustainably, look for fish that are certified by organizations like the Marine Stewardship Council. Prioritize species like Alaskan salmon, which come from well-managed fisheries, and consider smaller species that reproduce quickly.