What is the cleanest seafood to eat?

November 3, 2025 •

4 min read

According to advice from the FDA and EPA, certain populations should limit fish with high mercury levels, making many people question what is the cleanest seafood to eat. By prioritizing sustainably-sourced options and those lower on the food chain, consumers can make safer choices that minimize exposure to harmful contaminants like mercury.

Quick Summary

This guide outlines the factors determining clean seafood, focusing on species with low mercury content and sustainable sourcing. Key considerations include bioaccumulation and environmental impact, along with specific examples of the safest fish and shellfish options to enjoy regularly.

Key Points

Prioritize Low-Mercury Species: Smaller, shorter-lived fish like sardines, anchovies, and Atlantic mackerel are your best bet for low mercury levels.
Opt for Sustainable Certifications: Look for seafood certified by organizations like the MSC or ASC to ensure responsible harvesting and farming.
Choose Bivalves for Low Contaminants: Clams, oysters, and mussels are excellent, low-mercury choices that can also benefit the environment.
Limit High-Mercury Predators: Avoid or limit consumption of large predatory fish like swordfish, king mackerel, and some tuna species.
Select Wild Alaskan Salmon: This variety is typically lower in mercury than other salmon and is often sustainably managed.
Favor U.S.-Farmed Trout: Farmed rainbow trout from the U.S. is a clean, low-mercury, and eco-friendly option.

Understanding the Factors Behind 'Clean' Seafood

Defining what makes seafood "clean" involves more than just freshness; it requires evaluating potential contaminant levels, particularly mercury, and considering the environmental impact of its harvest. Two primary concerns for consumers are mercury content and the use of antibiotics or pollutants associated with certain farming methods.

The Dangers of Mercury

Mercury, a heavy metal, enters our waterways through industrial pollution and accumulates in fish tissue through a process called bioaccumulation. As larger predatory fish consume smaller fish, the mercury concentrates in their bodies, meaning the biggest fish tend to carry the highest levels of mercury. This makes smaller, shorter-lived fish a safer choice for regular consumption. The FDA and EPA provide guidance on which fish are considered 'Best Choices' with the lowest mercury levels.

The Role of Sustainable Sourcing

Beyond health concerns, the cleanliness of seafood also relates to its environmental footprint. Overfishing and poor aquaculture practices can harm marine ecosystems. Sustainable sourcing practices and third-party certifications help consumers make responsible choices. Labels from organizations like the Marine Stewardship Council (MSC) and the Aquaculture Stewardship Council (ASC) ensure that seafood is harvested responsibly, minimizing ecological damage.

The Cleanest Fish Choices

When selecting fish, focusing on smaller, shorter-lived species with low mercury levels is a reliable strategy for finding the cleanest options. These fish are often rich in beneficial omega-3 fatty acids with minimal contaminant exposure.

Sardines and Anchovies: These small, oily fish are low on the food chain, so they don't accumulate high levels of mercury. Canned sardines with bones also offer a great source of calcium and vitamin D.
Wild Alaskan Salmon: While salmon is larger, wild-caught Alaskan varieties are well-managed and typically have low mercury levels compared to other regions. Canned wild salmon is a very nutritious and convenient option.
Rainbow Trout (Farmed): U.S.-farmed rainbow trout, particularly those raised in indoor tanks or freshwater ponds, are considered a clean and sustainable choice, with minimal contaminant exposure.
Atlantic Mackerel: Smaller than its king mackerel counterpart, Atlantic mackerel has low mercury content and is packed with omega-3s.
Pacific Cod: This flaky white fish is high in protein and low in fat and mercury. Opt for Pacific varieties over depleted Atlantic stocks.

The Cleanest Shellfish Options

Shellfish are often a very clean option for seafood lovers. Bivalves like clams, oysters, and mussels are filter feeders, but when responsibly sourced, they are not high in mercury and can have a "nature positive" impact by filtering water.

Oysters: These bivalves are low in mercury and rich in essential minerals like zinc. Cooking them thoroughly is recommended to avoid foodborne illness.
Clams and Mussels: Both are excellent sources of protein, rich in omega-3s, and are among the most sustainable choices, especially when farmed.
Shrimp: One of the most popular seafood choices, shrimp are low in mercury and calories, while high in protein. Look for options with an Aquaculture Stewardship Council (ASC) label for responsibly farmed products.

Comparing Clean vs. Contaminant-Prone Seafood

To help you make informed decisions, this table compares some common clean seafood with options known for higher levels of contaminants.


Seafood Type	Mercury Level	Sustainability Notes	Other Considerations
Sardines	Low	Abundant stocks, quick to reproduce.	High in calcium (especially canned with bones).
Wild Alaskan Salmon	Low	Well-managed fisheries, low environmental impact.	High in omega-3s.
U.S. Farmed Rainbow Trout	Low	Raised in controlled systems, good eco-rating.	Good source of omega-3s and vitamin D.
Oysters & Mussels	Very Low	Often have a beneficial environmental impact.	Rich in minerals like zinc and B12.
King Mackerel	Highest	Vulnerable to overfishing.	Avoid due to high mercury accumulation.
Swordfish	Highest	Sustainable choices exist, but high mercury is the concern.	Limit consumption, especially for sensitive groups.
Orange Roughy	Highest	Slow to reproduce, susceptible to overfishing.	High mercury levels.
Bluefin Tuna	High	Overfishing is a major concern.	High mercury levels, consume sparingly.

Conclusion

Making informed choices about the seafood you eat is a crucial step towards a healthier and more sustainable diet. By opting for species that are smaller and lower on the food chain, such as sardines, mussels, and responsibly-farmed trout, you can significantly reduce your exposure to mercury. Always look for certifications from reputable organizations like MSC and ASC to ensure your choices are also environmentally sound. Prioritizing these clean and sustainable options allows you to enjoy the considerable health benefits of seafood without the risks associated with higher-mercury varieties. For official guidance on fish consumption, consult the FDA's advice about eating fish.

How to Find Cleaner Seafood

Look for Labels: Certifications like the Marine Stewardship Council (MSC) and Aquaculture Stewardship Council (ASC) indicate sustainable harvesting and farming practices.
Choose Smaller Fish: Smaller fish, like sardines and anchovies, have lower mercury levels because they are lower on the food chain.
Check Seafood Watch: The Monterey Bay Aquarium's Seafood Watch provides up-to-date recommendations on sustainable options.
Opt for Bivalves: Clams, oysters, and mussels are not only low in contaminants but can also have a positive environmental impact.
Inquire About the Source: At a fish counter or restaurant, don't be afraid to ask where the seafood was caught or farmed.

Safe Cooking Practices

No matter the type of seafood, proper cooking is essential to ensure food safety and minimize health risks. Always cook shellfish, like oysters, thoroughly, especially for those with weakened immune systems. For all seafood, cook until the flesh is opaque and flakes easily with a fork.

What About Canned Seafood?

Canned seafood can be a convenient and healthy option, but choices still matter. Canned light tuna (typically skipjack) is a better choice for lower mercury compared to canned albacore. Canned sardines and salmon are also excellent, low-mercury choices. When possible, choose products packed in water to reduce fat and calories.

Frequently Asked Questions

The seafood lowest in mercury generally includes smaller, short-lived species and bivalves like sardines, anchovies, rainbow trout, salmon (particularly wild Alaskan), shrimp, oysters, and clams.

Fish higher up the food chain, such as large predators like shark and swordfish, accumulate higher levels of mercury through bioaccumulation as they eat smaller fish. Those lower on the food chain, like sardines, have much lower levels.

The cleanliness of both depends on the source. Wild-caught can be exposed to environmental pollutants, while farm-raised can sometimes involve antibiotics, though some well-managed aquaculture facilities are very clean and sustainable, like U.S.-farmed rainbow trout. Certified seafood provides additional assurance.

Yes, look for eco-labels such as the Marine Stewardship Council (MSC) for wild-caught seafood and the Aquaculture Stewardship Council (ASC) for farmed seafood. These certifications indicate the product was sourced sustainably.

While Atlantic salmon is a healthy option, wild populations are often depleted. The Marine Conservation Society categorizes wild Atlantic salmon as 'a fish to avoid' due to low numbers, but farmed alternatives with ASC certification are available.

Yes, the FDA and EPA recommend that women who are or might become pregnant, as well as breastfeeding mothers and young children, eat fish from the 'Best Choices' list that are even lower in mercury, such as salmon, shrimp, and sardines.

The FDA lists several species with the highest mercury levels that should be limited or avoided by certain populations, including king mackerel, marlin, orange roughy, shark, swordfish, and bigeye tuna.