Which fish do not have heavy metals? A Guide to Safer Seafood

December 11, 2025 •

4 min read

According to the FDA, nearly all fish contain trace amounts of methylmercury, a type of heavy metal, but the levels vary significantly depending on the species. For those concerned about contamination, knowing which fish do not have heavy metals in high concentrations is key to enjoying seafood's numerous health benefits safely.

Quick Summary

This guide provides an overview of fish species known for having very low levels of heavy metals like mercury. It explains why some fish accumulate fewer contaminants, offers a comparison of low-mercury options, and discusses how to incorporate healthier seafood into a balanced diet.

Key Points

Bioaccumulation: Larger, older, predatory fish accumulate higher levels of heavy metals like mercury through a process called biomagnification.
Smaller is Safer: Smaller, shorter-lived fish that eat lower on the food chain contain the lowest amounts of heavy metals.
FDA 'Best Choices': Focus on fish categorized by the FDA as 'Best Choices,' which includes species such as salmon, sardines, and tilapia.
Healthy Options: Safe fish like salmon, sardines, and trout are packed with omega-3s, protein, and other vital nutrients.
Informed Choices: For canned tuna, select 'light' (skipjack) over 'albacore' (white) to reduce mercury intake.
Cooking Does Not Help: Cooking methods do not remove heavy metals, so choosing the right fish is the most important step.
Rotation is Recommended: Vary your fish intake to minimize exposure from a single species or location.

Understanding Heavy Metal Accumulation in Fish

Heavy metals, such as mercury, cadmium, and lead, enter waterways through both natural processes and industrial pollution. Within the aquatic ecosystem, these metals are absorbed by aquatic organisms and can accumulate in their tissues. A process known as biomagnification occurs when larger, predatory fish eat smaller, contaminated fish, causing the heavy metal concentration to increase up the food chain. Consequently, larger, longer-lived fish tend to have the highest levels of heavy metals, posing a greater risk to human health when consumed frequently.

Conversely, smaller, shorter-lived fish that feed lower on the food chain, such as on plankton or smaller crustaceans, have less time and opportunity to accumulate high levels of these contaminants. This is the primary reason why species like sardines, anchovies, and shellfish generally represent safer options. Choosing a variety of fish from different sources also helps to minimize exposure from a single contaminated location.

Best Choices: Fish with Lowest Heavy Metal Levels

Health authorities like the FDA and EPA regularly update their advice on seafood consumption to help consumers make informed decisions. Their guidance often categorizes fish into 'Best Choices,' 'Good Choices,' and 'Choices to Avoid' based on their average mercury levels. Focusing on the 'Best Choices' list is the most effective strategy for reducing heavy metal intake.

Key characteristics of these low-metal fish include:

Short Lifespan: They have less time to accumulate contaminants.
Lower Trophic Level: They feed on organisms at the bottom of the food chain, which have lower metal concentrations.
Smaller Size: Generally, smaller fish have lower levels of heavy metals.

A Comprehensive List of Low-Mercury Fish

Salmon: A favorite for its high omega-3 content, salmon has very low mercury levels.
Sardines: These small, oily fish are exceptionally low in mercury and high in nutrients.
Anchovies: Like sardines, anchovies are small, short-lived, and at the bottom of the food chain, making them a very safe option.
Cod: A lean, white fish that is consistently ranked as a 'Best Choice'.
Tilapia: A popular, fast-growing farmed fish with very low mercury levels.
Trout (freshwater): This fish typically has low mercury levels, especially when caught from clean, remote waters.
Shrimp: This shellfish is consistently among the lowest in mercury.
Oysters: Another excellent shellfish choice with very minimal heavy metal content.
Pollock: Often used in fish sticks, pollock is a low-mercury, abundant whitefish.

Comparing Seafood Options: Low vs. High Heavy Metal Content

To illustrate the importance of choosing wisely, here is a comparison of fish and shellfish with low and high heavy metal content, primarily focusing on mercury. Concentrations are average parts per million (ppm).


Feature	Low Heavy Metal Fish (Examples: Sardines, Salmon)	High Heavy Metal Fish (Examples: Shark, Swordfish)
Lifespan	Shorter lifespan, often less than 5 years	Longer lifespan, often living for decades
Trophic Level	Lower on the food chain, consuming plankton or small crustaceans	Apex predators, consuming many smaller fish
Average Mercury (ppm)	Salmon (~0.02 ppm), Sardines (~0.01 ppm)	Shark (~0.98 ppm), Swordfish (~1.00 ppm)
Recommended Consumption	Two to three servings per week for the general population	Best to avoid, especially for pregnant women and young children
Nutritional Profile	Rich in omega-3s, protein, calcium, and vitamin D	High in protein but also carries higher contamination risk

How to Safely Incorporate Low-Metal Fish into Your Diet

Adopting a varied diet that includes fish low in heavy metals is a sustainable way to enjoy its health benefits. Here are some tips:

Eat smaller fish: Focus on smaller, younger fish that are naturally lower in mercury.
Prioritize variety: Rotate your protein sources to prevent over-reliance on any single type of fish.
Check local advisories: For fish you catch yourself, consult local health or environmental agencies for any specific warnings in your area.
Understand canned tuna: Choose canned light tuna (typically skipjack), which is lower in mercury than canned albacore (white) tuna.
Consider wild vs. farmed: Both wild-caught and farmed salmon generally have low mercury levels, but sourcing from reputable suppliers is always recommended.

The Takeaway

While it is virtually impossible to find fish with zero heavy metals, making smart choices can dramatically reduce your exposure while still providing essential nutrients like omega-3 fatty acids, protein, and vitamin D. The key is to select smaller, shorter-lived fish from the lower end of the food chain. By following the recommendations from health authorities and diversifying your seafood consumption, you can confidently enjoy the health benefits of fish without unnecessary risk.

Important Disclaimer: The information presented here is for general informational purposes only and does not constitute medical advice. Please consult with a healthcare professional for dietary recommendations.

Frequently Asked Questions

Fish with the lowest mercury levels include shellfish like shrimp, scallops, and oysters, as well as small fish like sardines and anchovies. Catfish, tilapia, and canned light tuna are also consistently low in mercury.

The amount of heavy metals in a fish depends on several factors, including its position on the food chain, its lifespan, and the pollution level of its habitat. Large, predatory fish that live longer accumulate more heavy metals through a process called biomagnification.

No fish is completely free of heavy metals, as trace amounts are present in all waterways. However, by choosing fish with consistently low levels, such as those recommended by the FDA, consumers can significantly minimize their exposure.

Health authorities recommend that most adults can safely eat two to three servings (8 to 12 ounces) of low-mercury fish per week. Specific advice may vary for pregnant or breastfeeding women and young children.

No, cooking methods such as frying, grilling, or poaching do not remove heavy metals from fish. Mercury, in particular, is bound to the protein in fish muscle and cannot be cooked out.

Pregnant women and young children should not avoid all fish, as seafood provides essential nutrients for development. However, they should strictly avoid high-mercury fish and limit consumption to recommended amounts of low-mercury varieties.

Canned light tuna, which is typically made from skipjack fish, contains significantly less mercury than canned albacore (white) tuna. Canned light tuna is considered a 'Best Choice,' while albacore is often a 'Good Choice' for consumption.