Nutrition Guide: How often should I eat fish to avoid mercury?

October 17, 2025 •

4 min read

According to the U.S. Dietary Guidelines, eating fish as part of a healthy diet is highly recommended for its numerous health benefits, but it is important to know how often should I eat fish to avoid mercury. The key lies in selecting species with lower mercury levels and varying your choices to minimize risk while maximizing nutritional intake.

Quick Summary

Official guidelines recommend regular fish consumption from low-mercury choices, while advising limits or avoidance of high-mercury types. This balance ensures you gain crucial omega-3s and other nutrients while minimizing exposure to methylmercury, which is especially important for pregnant women and children.

Key Points

Follow FDA/EPA Guidelines: Adhere to the recommended 2-3 servings per week from the "Best Choices" list to manage mercury intake.
Choose Low-Mercury Fish: Prioritize species like salmon, sardines, and canned light tuna, which are lowest in mercury.
Limit Moderate-Mercury Fish: Reduce intake of “Good Choices” fish like albacore tuna to no more than one serving per week.
Avoid High-Mercury Fish: Stay away from large predators like shark, swordfish, and king mackerel, especially if you are pregnant or a child.
Vary Your Choices: Diversifying your seafood intake helps prevent the accumulation of mercury from a single source.
Cooking Does Not Remove Mercury: Since mercury is in the fish's muscle tissue, preparation methods like trimming or cooking do not reduce its content.

The Dual Nature of Fish: Benefits and Risks

Fish and shellfish are nutritional powerhouses, providing high-quality protein, essential vitamins, and crucial minerals like iodine and iron. A key benefit is the high concentration of omega-3 fatty acids, specifically EPA and DHA, which are vital for heart health, brain function, and infant development. However, the modern aquatic environment also contains mercury, a naturally occurring element that is converted into the neurotoxin methylmercury by aquatic bacteria.

The Process of Bioaccumulation

Methylmercury poses a risk because it accumulates in the fatty tissues of fish, a process known as bioaccumulation. This means that larger, older, and predatory fish, which sit at the top of the food chain, tend to have the highest concentrations of mercury in their systems. This is why public health organizations advise limiting or avoiding certain species with historically high mercury levels, while promoting the consumption of smaller, low-mercury fish.

Official Guidance on Fish Consumption

To help consumers navigate the risks and benefits, the U.S. Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) provide a clear framework. This guidance is especially critical for vulnerable populations like pregnant women, breastfeeding women, and young children, whose developing nervous systems are most sensitive to mercury's effects. The recommendations categorize fish into three levels based on their typical mercury content:

Best Choices: You can enjoy 2 to 3 servings per week of these low-mercury options. A typical adult serving size is 4 ounces before cooking.
Good Choices: Limit yourself to 1 serving per week of these fish, as they contain higher mercury levels.
Choices to Avoid: These fish have the highest mercury levels and should be avoided entirely by vulnerable groups.

Safe Portions for Adults and Children

For most adults, the FDA and EPA recommend eating 2 to 3 servings of a variety of fish per week, from the "Best Choices" list. For those who are pregnant or breastfeeding, the recommendation is 8 to 12 ounces per week of "Best Choices" fish. For children, portion sizes are adjusted by age and body weight, with children typically advised to have 2 servings a week from the "Best Choices" list.

Making Informed Choices: A Guide to Fish Selection

Choosing the right fish is the most effective way to manage mercury intake. Understanding which fish fall into which category empowers you to create a balanced diet without forgoing the benefits of seafood. Here is a breakdown of common fish species based on their mercury content:

Low- and High-Mercury Fish Comparison


Low-Mercury Fish (Best Choices)	High-Mercury Fish (Choices to Avoid)
Salmon (Wild or Canned)	Shark
Sardines	Swordfish
Anchovies	King Mackerel
Canned Light Tuna (Skipjack)	Bigeye Tuna
Tilapia	Marlin
Pollock	Orange Roughy
Shrimp	Tilefish (Gulf of Mexico)
Catfish	Chilean Sea Bass
Cod	Grouper
Scallops	Bluefish

Practical Tips for Reducing Mercury Exposure

Beyond choosing the right species, you can take other steps to further reduce your exposure to mercury and other contaminants:

Vary Your Fish Intake: By rotating your consumption of different fish and seafood species, you reduce the risk of accumulating mercury from any single source.
Consider Origin: Smaller, wild-caught fish, or sustainably farmed fish with proper monitoring, can sometimes be lower in contaminants.
Heed Local Advisories: If you consume fish caught recreationally, always check for local fish consumption advisories. These are issued by state or local health departments for specific water bodies.
Don't Rely on Cooking: Note that mercury is stored in the muscle tissue of the fish and cannot be removed by cooking or trimming fat. The only way to reduce mercury exposure is by making wise consumption choices.

The Critical Role of Fish for Pregnant Women and Children

For those who are pregnant, breastfeeding, or planning to become pregnant, fish is a vital part of a healthy diet, not to be avoided entirely. The omega-3 fatty acids in low-mercury fish are critical for the baby’s brain and nervous system development. The FDA emphasizes that the benefits of consuming recommended amounts of low-mercury fish far outweigh the risks for these groups. By following the guidelines and focusing on low-mercury choices, you can safely provide these essential nutrients for yourself and your baby.

Conclusion

In conclusion, incorporating fish into your diet is a highly beneficial practice for overall health, including supporting heart and brain function. The question of how often should I eat fish to avoid mercury is best answered by following official guidelines from the FDA and EPA. By prioritizing low-mercury varieties, moderating consumption of moderate-mercury fish, and avoiding those with the highest levels, you can enjoy seafood safely. Eating a variety of fish and paying attention to local advisories are simple yet powerful strategies to reap the rewards of this healthy food source without the concern of excessive mercury exposure. For more detailed information on specific fish species, the FDA/EPA advice page is an excellent resource.

Frequently Asked Questions

For most adults, the FDA and EPA recommend eating 2 to 3 servings (about 8-12 ounces) of a variety of fish per week, choosing primarily from the "Best Choices" category.

The primary risk is posed by methylmercury, a potent neurotoxin that accumulates in fish and can be harmful to the developing brain and nervous system, particularly in a fetus or young child.

Large, predatory fish typically have the highest mercury levels. Fish to avoid include shark, swordfish, king mackerel, bigeye tuna, marlin, and tilefish from the Gulf of Mexico.

No, cooking fish does not remove mercury. Unlike other contaminants like PCBs, mercury is present in the fish's muscle tissue, not its fat, so preparing it in different ways does not reduce the mercury content.

Canned light tuna (typically skipjack) is considered a "Best Choice" and can be safely consumed 2 to 3 times per week. Canned albacore (white) tuna has more mercury and is a "Good Choice," so it should be limited to one serving per week.

Pregnant women, breastfeeding women, women who may become pregnant, and young children are the most vulnerable and should pay special attention to the type and amount of fish they consume.

Excellent low-mercury fish include salmon, sardines, anchovies, cod, tilapia, catfish, shrimp, and scallops. These options provide important nutrients like omega-3s with minimal mercury risk.