Does Seabass Have High Levels of Mercury? What You Need to Know

December 16, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA) and Environmental Protection Agency (EPA), a single species labeled as 'seabass'—Chilean seabass—falls into the 'Good Choices' category for mercury levels, while other species, like Black sea bass, are considered 'Best Choices'. This variation means it's crucial to understand the specific type of seabass you are consuming to accurately assess the mercury risk.

Quick Summary

The mercury content in seabass varies significantly depending on the species and its place in the food chain. Certain types, like Chilean seabass, have higher mercury and should be limited, while others, such as Black sea bass, are low in mercury. Key factors affecting mercury accumulation include the fish's diet, lifespan, and size.

Key Points

Not a Single Answer: Mercury levels in seabass vary significantly by species, with some types being low-mercury and others moderate.
Chilean Sea Bass has Higher Mercury: Chilean seabass (Patagonian toothfish) is a larger, predatory fish and contains higher levels of mercury, classified as a "Good Choice" by the FDA.
Black Sea Bass has Low Mercury: The smaller Black sea bass is a "Best Choice" with low mercury levels, safe for more frequent consumption.
Understand Bioaccumulation: Mercury levels increase up the food chain, so larger, longer-lived predator fish accumulate more mercury than smaller species.
Check the Label: Always verify the specific species of seabass you are purchasing to make an informed decision about its mercury content and consumption frequency.
Consider Vulnerable Groups: Pregnant women, breastfeeding mothers, and young children should be especially mindful of guidelines and limit consumption of higher-mercury species.

Understanding Mercury in Seabass: Not All Species Are Equal

Mercury is a naturally occurring element that can be released into the environment, where it is converted into methylmercury by bacteria. This toxic form then bioaccumulates in aquatic organisms, including fish. As it moves up the food chain, the concentration of mercury increases, a process called biomagnification. Larger, longer-lived predatory fish tend to have the highest levels of mercury.

The term "seabass" is a common name used for a variety of fish species, and not a single classification. This ambiguity is why it's vital to know the specific type you are buying. The mercury content differs dramatically between, for example, a Chilean seabass and a Black sea bass. While both can be part of a healthy diet, understanding the distinctions allows for safer consumption habits.

Mercury Levels by Seabass Species

There are many fish sold as 'seabass', and their mercury content reflects their specific diet and habitat. Here are some examples based on FDA data:

Chilean Sea Bass (Patagonian Toothfish): This deep-water predator is a large, long-lived fish, which means it has a longer time to accumulate mercury. It is categorized by the FDA as a "Good Choice," suggesting limiting consumption to one serving per week for vulnerable populations like pregnant women and young children. Studies have shown that Chilean sea bass can have average mercury loads of around 0.354 ppm.
Black Sea Bass: In contrast, this species is much smaller and has a shorter lifespan than its Chilean counterpart. The FDA lists Black sea bass as a "Best Choice," meaning it's a very low-mercury option that can be enjoyed two to three times a week.
European Sea Bass: A 2021 study on fish in the Mediterranean indicated that European seabass had a low mean mercury concentration of 0.13 mg/kg. This also puts it in the lower-risk category for regular consumption.

The Bioaccumulation Factor: Why Size Matters

The primary reason for the discrepancy in mercury levels among seabass species is bioaccumulation. Large predatory fish consume smaller fish, inheriting the mercury those fish have accumulated. Over a long life, this process magnifies, leading to higher concentrations in older, larger specimens. For example, a study in the Gulf of Mexico found a positive relationship between the total mercury content and the length and age of seabasses. In contrast, smaller seabass species, which feed on invertebrates or small plankton, will have considerably lower mercury burdens.

Navigating the Seabass Market

Since the labeling can be confusing, here are a few tips to help you make an informed choice:

Always read the label. Responsible seafood vendors should label the specific type of fish. If it simply says "seabass," ask for more information about the species and origin.
Choose a reputable vendor. Purchase your fish from a fishmonger or market you trust that can provide details on the fish's provenance and species.
Consider the source. The waters a fish comes from can also affect its mercury levels. Local advisories should be consulted for recreationally caught fish.

Comparison of Seabass and Other Common Fish

To put the mercury levels into perspective, here is a comparison table using FDA data:


Fish Species	Mercury Level Category	Average Mercury (PPM)
Chilean Sea Bass	Good Choice	0.354
Black Sea Bass	Best Choice	0.13
European Sea Bass	Best Choice (based on EU study)	0.13
Salmon	Best Choice	0.022
Canned Light Tuna	Best Choice	0.126
Albacore Tuna	Good Choice	0.350
Swordfish	Avoid	0.995
Shark	Avoid	0.979

Health Implications and Recommendations

For most healthy adults, consuming seabass in moderation does not pose a significant mercury risk. The main concern is for sensitive populations, including pregnant or breastfeeding women and young children, whose developing nervous systems are more vulnerable to the neurotoxic effects of mercury. The FDA and EPA guidelines are designed to help these groups make safer choices. Eating a variety of low-mercury fish can provide important nutrients like Omega-3 fatty acids with minimal risk.

Conclusion

Does seabass have high levels of mercury? The answer is nuanced. While some varieties, particularly the large, predatory Chilean seabass, have higher concentrations and should be consumed in moderation, other smaller seabass species, such as Black sea bass and European sea bass, are low-mercury options that can be enjoyed more frequently. The key is to be an informed consumer by understanding the specific species you are purchasing and following the consumption guidelines from authoritative bodies like the FDA and EPA. By making mindful choices, you can continue to enjoy the nutritional benefits of seafood while minimizing mercury exposure. For more detailed information on species and mercury content, refer to the FDA's Advice About Eating Fish and Shellfish.

Frequently Asked Questions

Chilean seabass is a large, long-lived predator with higher mercury levels, listed as a 'Good Choice' by the FDA, limiting recommended consumption. The smaller Black seabass has much lower mercury levels and is considered a 'Best Choice'.

The frequency depends on the species. For Chilean seabass, the FDA recommends limiting consumption to one serving per week for vulnerable individuals. For low-mercury varieties like Black sea bass, consumption can be two to three times per week.

No, cooking does not remove mercury from fish. The mercury is bound to the fish's muscle tissue, so it remains in the meat regardless of cooking method.

High levels of mercury, particularly methylmercury found in fish, can act as a neurotoxin, potentially damaging the nervous system. The risk is especially high for developing fetuses and young children.

Other low-mercury options include salmon, sardines, scallops, shrimp, cod, and canned light tuna. These are often categorized as 'Best Choices' by health organizations.

Mercury levels are influenced by a fish's size and age, not just its source. Therefore, focusing on smaller, shorter-lived species is a more reliable strategy for reducing mercury intake than trying to find a low-mercury version of a species known to have higher levels.

The body eliminates mercury over time, so one week of high intake is not a significant concern. You can simply reduce or avoid eating high-mercury fish for the following week or two to balance your average intake.