Fish and Mercury: What Official Advice Says
What the FDA, EPA, U.S. Dietary Guidelines, NHS and WHO say about mercury in fish, the Best Choices, Good Choices and Choices to Avoid lists, and who the advice is for.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
Official advice is to keep eating fish, but to choose kinds that are lower in mercury, especially during pregnancy and breastfeeding and for young children. The FDA and EPA publish one chart for this, last revised in October 2021. [1]
How the sources define the terms
- Methylmercury is the form of mercury found in fish. People are mainly exposed to it when they eat fish and shellfish that contain it. [2]
- Mercury builds up as it moves up the food chain, so large predatory fish are more likely to have high levels. [2]
- The FDA and EPA use "fish" to mean fish and shellfish together, and sort species into Best Choices, Good Choices and Choices to Avoid. [1]
- A serving for adults is 4 ounces, about the size of the palm of a hand. For children it is about 1 ounce at age 1 to 3, 2 ounces at age 4 to 7, 3 ounces at age 8 to 10 and 4 ounces at age 11. [1]
What the official advice says
| Body and year | Who it is for | What it says |
|---|---|---|
| FDA and EPA, revised 2021 | People who are or might become pregnant, or breastfeeding | 2 to 3 servings a week from "Best Choices," or 1 serving from "Good Choices." [1] |
| FDA and EPA, revised 2021 | Children | 2 servings a week from "Best Choices." [1] |
| U.S. Dietary Guidelines 2020-2025 | Children who eat the higher amounts in the Guidelines | Only fish from a shorter group of "Best Choices" that are even lower in mercury, named in a footnote on the FDA page (for example salmon, sardines, shrimp, tilapia and trout). [1] |
| NHS, UK | Pregnant, trying to conceive or breastfeeding | Do not eat shark, swordfish or marlin. If pregnant or trying, no more than 4 cans or 2 steaks of tuna a week; no limit on tuna while breastfeeding. Oily fish: no more than 2 portions a week. [3] |
| WHO | General | Exposure of the fetus to methylmercury poses danger to the unborn child. [2] |
Notice that countries word the advice differently, so read the body and year before comparing.
The FDA and EPA lists
The FDA's text version of the chart names these species. [4]| List | Species named |
|---|---|
| Best Choices | Anchovy, Atlantic croaker, Atlantic mackerel, black sea bass, butterfish, catfish, clam, cod, crab, crawfish, flounder, haddock, hake, herring, lobster (American and spiny), mullet, oyster, Pacific chub mackerel, perch (freshwater and ocean), pickerel, plaice, pollock, salmon, sardine, scallop, shad, shrimp, skate, smelt, sole, squid, tilapia, freshwater trout, canned light tuna (includes skipjack), whitefish, whiting |
| Good Choices | Bluefish, buffalofish, carp, Chilean sea bass, grouper, halibut, mahi mahi, monkfish, rockfish, sablefish, sheepshead, snapper, Spanish mackerel, ocean striped bass, Atlantic tilefish, albacore (white) tuna canned and fresh or frozen, yellowfin tuna, weakfish, white croaker |
| Choices to Avoid (highest mercury) | King mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, bigeye tuna |
Species names can hide differences: mackerel, tuna and tilefish each appear on more than one list, depending on the species.
What research and agencies found about benefits and harms
| Question | What the source found | Strength of evidence |
|---|---|---|
| Fish in pregnancy and the child's brain development | A 2015 systematic review of 8 studies concluded that benefits of moderate fish intake in pregnancy outweighed possible harms for neurodevelopment, as long as the fish is low in mercury. [5] | Promising but limited (observational) |
| Fish intake in pregnancy and the baby's cognitive development | The FDA says moderate scientific evidence shows it can help. [1] | Statement of an agency |
| Health effects of mercury | WHO reports that mercury's health impacts include kidney and nervous system damage. [2] | Agency statement |
Related
Oily fish, Foods in pregnancy and Foods for babies and toddlers.Frequently asked questions
Is salmon high in mercury?
No. The FDA and EPA list salmon as a "Best Choice," and the U.S. Dietary Guidelines name salmon among seafood higher in EPA and DHA and lower in methylmercury. [4] [9]
Is canned tuna safe?
It depends on the type and who is eating it. The FDA and EPA list canned light tuna (including skipjack) as a "Best Choice" and canned albacore (white) tuna as a "Good Choice." [4] The NHS gives a weekly limit on cans for people who are pregnant or trying to become pregnant. [3]
Which fish do officials say to avoid?
King mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish and bigeye tuna are the "Choices to Avoid" for the groups the advice covers. [4]
How much fish can children eat?
The FDA and EPA say 2 servings a week from "Best Choices," with serving sizes by age. [1] Ask the child's clinician about the right amount for that child.
Does eating fish in pregnancy harm the baby?
Mercury is a concern, so official advice is to choose lower-mercury fish. [1] A 2015 review found benefits outweighed harms when moderate amounts of low-mercury fish were eaten. [5] Ask your clinician.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits and uncertainty
- The lists sort whole species. They do not tell a reader the mercury level of a particular fillet. Proper evidence not found in the sources we read for how much individual fish vary within a species.
- We did not read the FDA's mercury measurement table, so this page does not quote parts-per-million values.
- Fish also vary in other contaminants. The NHS says oily fish usually have higher levels of pollutants than other seafood. [3] See Heavy metals and contaminants in foods.
Safety and individual considerations
- Fish caught by family or friends. The FDA says to check local fish and shellfish advisories; if there is none, eat only one serving and no other fish that week. [1]
- Raw, smoked and cured fish. The NHS advises pregnant people to avoid raw, cold-smoked and cured fish because it could contain listeria. [6] See Raw sprouts, raw milk and undercooked foods.
- Allergy. Fish is a major food allergen in the U.S. [7] Call 911 for serious or whole-body reactions. [8]
- Fish oil capsules are a separate product; see Fish oil.
References
- U.S. Food and Drug Administration and U.S. Environmental Protection Agency. Advice about Eating Fish, revised October 2021. Read 2026-10-23.
- World Health Organization. Mercury and health. Read 2026-10-23.
- NHS (UK). Fish and shellfish in your diet. Read 2026-10-23.
- U.S. Food and Drug Administration and U.S. Environmental Protection Agency. Advice about Eating Fish: text versions of the Best Choices, Good Choices and Choices to Avoid lists, revised October 2021. Read 2026-10-23.
- Fish intake during pregnancy and foetal neurodevelopment--a systematic review of the evidence. Nutrients 2015. PMID 25793632. Read 2026-10-23.
- NHS (UK). Foods to avoid in pregnancy. Read 2026-10-23.
- U.S. Food and Drug Administration. Food Allergies. Read 2026-10-23.
- MedlinePlus. Food allergy. Read 2026-10-23.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025, seafood subgroup and Appendix 3 (protein foods subgroups). Read 2026-10-23.