Official Fish-Eating Advice and Mercury: What FDA/EPA, NHS and Health Canada Say for Different Groups
What the FDA and EPA, the NHS and Health Canada say about how much fish to eat and which fish to limit because of mercury, for pregnancy, breastfeeding and children.
Content last updated . This page has not been medically reviewed.
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These are public-health rules for three countries, not personal advice. Each body writes for its own population, with its own fish and its own serving sizes, so one country's number should not be copied to another. Pregnant or breastfeeding, planning a pregnancy, or feeding a child? A midwife, doctor or dietitian can apply these rules to your situation. If you think a child has been poisoned by anything, call Poison Help at 1-800-222-1222 in the US; other countries are on the Poison Help by country page.Why mercury is in the advice
Mercury in fish is a concern mainly for a developing baby. The NHS says that shark, swordfish and marlin can contain more mercury than other fish and can damage a developing baby's nervous system. [1] The FDA and EPA say it is important to limit mercury in the diets of people who are pregnant or breastfeeding, and in children, while many types of fish are both nutritious and lower in mercury. [2]A 2006 review in JAMA weighed benefits and risks. It concluded that for adults the benefits of fish intake exceed the potential risks, and that for women of childbearing age modest intake, apart from a few selected species, also outweighs risk. [3] That is one review from 2006; the official advice below is newer.
What each body says, by group
| Group | United States: FDA and EPA (revised 2021) | United Kingdom: NHS (page reviewed June 2026) | Canada: Health Canada (page modified July 2024) |
|---|---|---|---|
| General adults | At least 8 ounces of seafood a week on a 2,000-calorie diet [2] | At least 2 portions of fish a week, one of them oily; a portion is around 140 g [1] | Higher-mercury fish (fresh or frozen tuna, shark, swordfish, marlin, orange roughy, escolar): 150 g per week [4] |
| Pregnant or breastfeeding | 2 to 3 servings a week from the "Best Choices" list, or 1 serving from the "Good Choices" list; a serving is 4 ounces [2] | No more than 2 portions of oily fish a week; no more than 4 cans or 2 steaks of tuna a week while pregnant or trying (no tuna limit while breastfeeding) [1] | Higher-mercury fish: 150 g per month for women who are or may become pregnant, or are breastfeeding [4] |
| Children | 2 servings a week from "Best Choices"; a serving is about 1 ounce at age 1 to 3, 2 ounces at 4 to 7, 3 ounces at 8 to 10 and 4 ounces at 11 [2] | Under 16: avoid shark, swordfish and marlin; boys up to 4 portions of oily fish a week, girls no more than 2 [1] | Higher-mercury fish: 125 g per month at ages 5 to 11 and 75 g per month at ages 1 to 4 [4] |
Health Canada's page says 150 grams is about one cup, and that the numbers above do not apply to canned light tuna. [4] Our reading of the Health Canada page came through a web-reading tool that returns quoted text, not a direct download.
Fish named in the advice
- United States, "Choices to Avoid" (highest mercury): king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish and bigeye tuna. [2]
- United States, "Best Choices" include: salmon, sardine, anchovy, Atlantic mackerel, herring, trout, pollock, cod, shrimp and canned light tuna. [2]
- United States, "Good Choices" include: halibut, albacore (white) tuna, yellowfin tuna, mahi mahi and snapper. [2]
- United Kingdom, in pregnancy: shark, swordfish and marlin should not be eaten; other adults should have no more than 1 portion a week. [1]
- Canada: the fish to eat less often are listed in the table above. [4]
Related points from the same pages
- Family-caught fish (US): check local advisories; if there is none, eat only one serving and no other fish that week. [2]
- Smoked and raw fish in pregnancy (UK): the NHS says to avoid raw fish, raw shellfish and cold-smoked fish unless cooked until steaming hot, because of listeria and other infections. [5]
- Cod liver oil (UK): unless a doctor advises otherwise, avoid fish liver oil supplements when pregnant or trying, because they are high in vitamin A (retinol). [1] See cod liver oil: vitamin A and D content and pregnancy caution.
- Why the UK limits oily fish: pollutants in oily fish can build up in the body and affect a future baby's development. [1]
What these sources do not cover
We could not read the EFSA opinion on seafood and mercury for the EU: the pages returned an access error. No EU fish-serving figure is given here. Proper evidence not found in the sources we read for a single "universal" weekly fish limit; the three bodies above differ. For supplements and pregnancy, see omega-3 and DHA in pregnancy and pregnancy and breastfeeding safety. Purity of fish oil capsules is a different question: see fish oil purity.Frequently asked questions
How much fish is safe in pregnancy?
It depends on the country. The FDA and EPA say 2 to 3 servings of 4 ounces a week from the Best Choices list. [2] The NHS says no more than 2 portions of oily fish a week and limits on tuna. [1]
Which fish should I avoid because of mercury?
The FDA and EPA list king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish and bigeye tuna. [2]
Is canned tuna safe to eat?
The FDA and EPA place canned light tuna in Best Choices and albacore in Good Choices. [2] The NHS caps tuna at 4 cans a week in pregnancy. [1]
Can children eat fish?
All three bodies give child-specific advice: serving sizes in the US, avoiding shark, swordfish and marlin in the UK, and monthly limits for higher-mercury fish in Canada. [2][1][4]
Does fish oil carry the same mercury risk?
Proper evidence not found in the advice pages above, which cover fish as food. See the fish oil purity page for supplements.
References
- NHS, Fish and shellfish. Read 2026-10-23.
- FDA and EPA, Advice About Eating Fish (revised October 2021). Read 2026-10-23.
- Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA 2006. Read 2026-10-23.
- Health Canada, Mercury in fish (page modified 2024-07-25; read through a web-reading tool). Read 2026-10-23.
- NHS, Foods to avoid in pregnancy. Read 2026-10-23.