What Fish is the Least Contaminated?

According to the FDA, certain small fish and shellfish contain significantly lower levels of contaminants like mercury compared to larger, predatory species. Navigating the choices at the seafood counter to find out what fish is the least contaminated can be challenging, but understanding a few key factors makes it simple to select the healthiest options.

Quick Summary

This guide provides an overview of fish and shellfish with the lowest levels of common contaminants, focusing on varieties with minimal mercury and polychlorinated biphenyls (PCBs) based on FDA and EPA data. It highlights smaller, non-predatory species and explores the differences between wild-caught and farmed fish.

Key Points

• Small, young fish have less mercury: Smaller, shorter-lived species like sardines and anchovies accumulate far less mercury than large predatory fish.

• Shellfish is generally low in contaminants: Shrimp, scallops, clams, and oysters contain very low levels of mercury and are safe for regular consumption.

• Wild Alaskan salmon is a top healthy choice: Wild-caught salmon, particularly from Alaska, is known for low contaminant levels and high omega-3 content, outperforming many farmed varieties.

• Prioritize canned 'light' tuna: When choosing canned tuna, opt for 'chunk light' (skipjack), which has lower mercury levels than canned 'white' (albacore).

• Avoid large, predatory species: The FDA and EPA recommend avoiding or limiting large, high-mercury fish such as shark, swordfish, and king mackerel.

• Diversify your seafood choices: Eating a variety of low-contaminant fish helps minimize exposure to any single type of pollutant.

• Sourcing matters for farmed fish: For farmed options like tilapia, verify the source to ensure sustainable practices are used and to avoid potential contamination from less-regulated farms.

Understanding Fish Contamination

Concerns about contaminants in fish, such as methylmercury and polychlorinated biphenyls (PCBs), are valid for consumers, especially pregnant women and young children. Mercury is a naturally occurring element that accumulates in the food chain, meaning larger, predatory fish that eat smaller fish tend to have higher concentrations. PCBs are industrial chemicals that persist in the environment and also build up in the fatty tissue of fish. Choosing fish with lower levels of these contaminants can reduce your overall exposure while still providing the numerous health benefits of seafood, such as protein and omega-3 fatty acids.

Why are some fish more contaminated than others?

Several factors influence the contaminant levels in fish:

• Position in the Food Chain: Predator fish at the top of the food chain, like shark and swordfish, accumulate more mercury and other contaminants than smaller, non-predatory species.
• Size and Lifespan: Older, larger fish have had more time to accumulate contaminants in their bodies.
• Wild vs. Farmed: Historically, farmed fish have shown higher levels of certain contaminants like PCBs, due to the concentrated feed and controlled environment of some fish farms. However, sustainable and well-regulated aquaculture is making strides to reduce this risk.

The Least Contaminated Seafood: Best Choices

For those seeking the safest options, government agencies like the FDA and EPA provide valuable guidance. The list of "Best Choices" is extensive and includes a wide variety of nutritious and delicious seafood. These fish and shellfish are consistently shown to have the lowest levels of mercury and other pollutants, making them safe for regular consumption by all populations, including pregnant women and young children.

Best Choices for Low Contamination

• Small Fish: Sardines, anchovies, herring, and Atlantic mackerel are excellent options. Because of their size and position lower on the food chain, they accumulate minimal mercury and are packed with omega-3s.
• Shellfish: Most shellfish, including shrimp, clams, oysters, and scallops, are considered very low in mercury and safe for frequent consumption.
• Whitefish: Varieties like cod, pollock, and haddock are lean, contain low mercury, and are great sources of protein and B vitamins.
• Tilapia: Farm-raised tilapia generally contains low levels of mercury, but sourcing is important due to potential farming practices that could introduce other contaminants. Look for tilapia from reputable countries like Ecuador or Taiwan.
• Salmon: Wild-caught salmon, particularly from Alaska, is a fantastic choice, known for its high omega-3 content and low levels of contaminants compared to some farmed varieties.

Comparison of Seafood Contaminant Levels

Seafood Type	Typical Mercury Level	Typical PCB Level	FDA/EPA Recommendation	Notes
Sardines	Very Low	Very Low	Best Choice	Tiny, oily fish with high omega-3s.
Wild Salmon (Alaska)	Very Low	Low	Best Choice	Excellent source of omega-3s.
Shrimp	Very Low	Very Low	Best Choice	Most consumed seafood in the US.
Cod	Low	Low	Best Choice	Lean, mild white fish.
Tuna (Canned Light)	Low	Low	Best Choice	Skipjack species is lower in mercury than Albacore.
Tuna (Albacore/White)	Moderate	Moderate	Good Choice	Should be limited, especially for vulnerable groups.
Swordfish	High	Variable	Avoid	Large predatory fish.
Shark	High	Variable	Avoid	Apex predator with high mercury levels.

Making the Safest Choices: Tips for Consumers

When selecting seafood, consider not only the type of fish but also its source and how it was harvested. Informed choices can significantly reduce your exposure to contaminants.

• Diversify your seafood: Don't eat the same type of fish all the time. Eating a variety of low-mercury fish, such as rotating between salmon, shrimp, and sardines, helps to minimize exposure and provides a wider range of nutrients.
• Know your source: Check labels for information on where and how the fish was caught or farmed. For example, Alaskan wild-caught salmon is a reliable low-contaminant option. For farmed fish, look for sustainability certifications like the Aquaculture Stewardship Council (ASC).
• Choose smaller, younger fish: Since contaminants accumulate over time, choosing smaller and younger fish reduces the likelihood of high mercury levels. This is why canned light tuna (typically smaller skipjack) is safer than tuna steaks (from larger species).
• Follow local advisories: If you consume fish caught recreationally from local waters, consult local health department advisories, as some areas may have specific warnings for certain species.
• Prioritize omega-3 rich, low-contaminant fish: Species like salmon, sardines, and anchovies offer the dual benefit of low contaminant levels and high concentrations of beneficial omega-3s.

Conclusion: Balancing Health Benefits with Safety

While contamination is a legitimate concern, it should not lead to avoiding fish altogether. The nutritional benefits of seafood, particularly the omega-3 fatty acids essential for brain and heart health, are well-documented. By focusing on the 'Best Choices' identified by health authorities like the FDA and EPA, consumers can confidently incorporate seafood into a healthy, balanced diet. Selecting smaller, non-predatory fish and shellfish, diversifying your choices, and paying attention to sourcing are the most effective strategies for minimizing contaminant exposure. With a little knowledge, you can ensure that the fish you eat is both delicious and safe for you and your family.

How to Find the Most Sustainable and Least Contaminated Fish

For reliable, up-to-date guidance, the Monterey Bay Aquarium's Seafood Watch program offers a comprehensive list of recommended seafood choices. Their ratings consider both environmental sustainability and contaminant levels. Their user-friendly guide helps you make informed choices while shopping or dining out.

What are the Least Contaminated Fish?

The Best Choices for Safest Fish

• Sardines
• Wild Alaskan Salmon
• Anchovies
• Shrimp
• Tilapia (select sources)
• Pollock
• Catfish
• Cod
• Scallops
• Mussels
• Clams

The Species to Limit or Avoid

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

Frequently Asked Questions

What is the primary reason large fish have more mercury?

Larger fish are higher up the food chain and live longer, allowing them more time to accumulate mercury from the smaller fish they eat through a process called biomagnification.

Is canned tuna a safe choice, and if so, what kind?

Yes, canned 'chunk light' tuna, made from the smaller skipjack species, is a 'Best Choice' according to the FDA due to its lower mercury content. Canned 'white' (albacore) tuna is a 'Good Choice' and should be eaten less frequently, particularly by vulnerable groups.

Are farmed fish always more contaminated than wild fish?

Not necessarily. While some older studies showed higher PCB levels in farmed salmon due to feed, modern, well-regulated aquaculture with certifications like the ASC uses improved feeds and practices to minimize contaminants. However, wild-caught Alaskan salmon is still a low-contaminant, high-omega-3 choice.

Does cooking fish remove the mercury?

No, cooking does not remove mercury from fish. Mercury is bound to the protein in the fish meat and cannot be eliminated through heating.

Which fish are recommended for pregnant women and young children?

Pregnant women and young children should prioritize seafood from the FDA's 'Best Choices' list, which includes salmon, shrimp, sardines, tilapia, and canned light tuna. They should avoid 'Choices to Avoid' fish like shark, swordfish, and king mackerel due to high mercury.

Are PCBs still a major concern in fish?

PCBs are legacy contaminants that persist in the environment and can accumulate in fatty fish. While levels have decreased over time, they are still a concern. Choosing wild-caught salmon and smaller, leaner fish helps minimize PCB exposure.

How do I check local fish advisories for contaminants?

If you catch fish yourself, you should check for local advisories from your state or local health department, which often provide specific guidance for bodies of water in your area.