Key takeaways
- Salmon is one of the lowest-mercury fish, averaging 0.022 parts per million (ppm) in FDA testing. Shrimp, sardines, tilapia, pollock and scallops are low too.
- Canned light tuna averages about a third of the mercury in canned albacore (0.126 vs 0.350 ppm).
- Swordfish, shark, king mackerel, bigeye tuna, marlin, orange roughy and Gulf of Mexico tilefish have the most. The FDA and EPA list them as choices to avoid.
- If you are pregnant or breastfeeding, the FDA and EPA suggest 2 to 3 servings a week from the best-choices list. Children should have 2 servings a week, sized for their age.
Why some fish have more mercury
Mercury comes from nature and from pollution, such as burning coal. It settles into lakes, rivers and oceans, where bacteria change it into methylmercury. Fish take in methylmercury from what they eat, and it builds up over their lives.[3]
That’s why big, long-lived fish that eat other fish, like swordfish and shark, have the most. Small fish and shellfish lower on the food chain have very little.
Methylmercury can harm the developing brain and nervous system, so it matters most during pregnancy and early childhood.[3] But fish is also one of the best sources of protein and omega-3 fats. The goal is to pick the right fish, not to skip it.[1]
Mercury in 22 common fish
Average mercury, parts per million (ppm)
- Scallops0.003
- Shrimp0.009
- Sardines0.013
- Tilapia0.013
- Salmon, fresh or frozen0.022
- Catfish0.024
- Pollock0.031
- Atlantic mackerel0.050
- Trout, freshwater0.071
- Cod0.111
- Tuna, canned light0.126
- Mahi mahi0.178
- Halibut0.241
- Tuna, canned albacore0.350
- Tuna, yellowfin0.354
- Marlin0.485
- Orange roughy0.571
- Tuna, bigeye0.689
- King mackerel0.730
- Shark0.979
- Swordfish0.995
- Tilefish, Gulf of Mexico1.123
One part per million means one microgram of mercury in every gram of fish. A 4-ounce portion weighs about 113 grams, so at these averages it would hold about 2.5 micrograms of mercury for salmon and about 112 for swordfish.
Is salmon high in mercury?
No. Salmon is one of the lowest-mercury fish you can buy. Fresh or frozen salmon averaged 0.022 ppm in FDA testing, and canned salmon 0.014 ppm.[2] The FDA and EPA list salmon as a best choice, without separating wild from farmed.[1]
Salmon is also rich in omega-3 fats, which makes it one of the easiest fish to eat often.
What about tuna?
Tuna spans all three FDA and EPA groups, depending on the kind. Canned light tuna averages 0.126 ppm and is a best choice. Canned albacore and yellowfin average about 0.35 ppm and are good choices. Bigeye averages 0.689 ppm and is a choice to avoid.[1][2]
If you eat tuna sandwiches often, light tuna is the easy swap. Our guide to mercury in tuna has the amount per can, how much tuna a week the advice allows, and what “ahi” means at the sushi counter.
The FDA and EPA fish lists
The FDA and EPA sort fish into three groups by mercury.[1] Their advice is written for people who are or might become pregnant, people who are breastfeeding, and children ages 1 to 11, but the lists are a useful guide for anyone.
Best choices: 2 to 3 servings a week
- Anchovy
- Atlantic croaker
- Atlantic mackerel
- Black sea bass
- Butterfish
- Catfish
- Clam
- Cod
- Crab
- Crawfish
- Flounder
- Haddock
- Hake
- Herring
- Lobster
- Mullet
- Oyster
- Pacific chub mackerel
- Perch
- Pickerel
- Plaice
- Pollock
- Salmon
- Sardine
- Scallop
- Shad
- Shrimp
- Skate
- Smelt
- Sole
- Squid
- Tilapia
- Trout, freshwater
- Tuna, canned light
- Whitefish
- Whiting
Good choices: 1 serving a week, in place of best choices
- Bluefish
- Buffalofish
- Carp
- Chilean sea bass
- Grouper
- Halibut
- Mahi mahi
- Monkfish
- Rockfish
- Sablefish
- Sheepshead
- Snapper
- Spanish mackerel
- Striped bass (ocean)
- Tilefish (Atlantic)
- Tuna, albacore
- Tuna, yellowfin
- Weakfish (seatrout)
- White croaker
Choices to avoid
- King mackerel
- Marlin
- Orange roughy
- Shark
- Swordfish
- Tilefish (Gulf of Mexico)
- Tuna, bigeye
| Who | Serving size | Each week |
|---|---|---|
| Pregnant or breastfeeding | 4 oz before cooking (about the size of your palm) | 2 to 3 servings of best choices, or 1 of good choices |
| Children 1 to 3 | About 1 oz | 2 servings of best choices |
| Children 4 to 7 | About 2 oz | 2 servings of best choices |
| Children 8 to 10 | About 3 oz | 2 servings of best choices |
| Children 11 | About 4 oz | 2 servings of best choices |
Caught your own fish? Check local fish advisories. If there aren’t any, the FDA suggests eating just one serving that week and no other fish.[1]
Questions people ask
- Is salmon high in mercury?
- No. Salmon is one of the lowest-mercury fish. Fresh or frozen salmon averaged 0.022 parts per million in FDA testing, and canned salmon 0.014. The FDA and EPA list salmon as a best choice.
- Which fish are lowest in mercury?
- In FDA testing, scallops, shrimp, sardines, tilapia, salmon, catfish and pollock had some of the lowest averages, all under 0.035 parts per million. All are on the FDA and EPA best-choices list.
- Which fish has the most mercury?
- In FDA testing, tilefish from the Gulf of Mexico had the most, averaging 1.123 parts per million, followed by swordfish, shark, king mackerel, bigeye tuna, orange roughy and marlin. The FDA and EPA list all of them as choices to avoid.
- How much fish should I eat while pregnant?
- The FDA and EPA suggest 2 to 3 servings a week from the best-choices list, or 1 serving from the good-choices list. A serving is 4 ounces before cooking, about the size of your palm. Avoid the highest-mercury fish, and eat seafood fully cooked rather than raw.
- Is shrimp high in mercury?
- No. Shrimp averaged 0.009 parts per million in FDA testing, among the lowest of any seafood, and it is on the best-choices list.
Sources
- [1]U.S. Food and Drug Administration and Environmental Protection Agency. Advice about eating fish. revised October 2021.
- [2]U.S. Food and Drug Administration. Mercury levels in commercial fish and shellfish (1990–2012). accessed October 2026.
- [3]U.S. Environmental Protection Agency. Health effects of exposures to mercury. accessed October 2026.
- [4]U.S. Food and Drug Administration. Questions and answers on FDA/EPA advice about eating fish. accessed October 2026.
- [5]U.S. Food and Drug Administration. Selecting and serving fresh and frozen seafood safely. accessed October 2026.
This article is for general information. It is not medical advice and does not replace a doctor, dietitian or pediatrician. Purus gives estimates for general information; it is not a medical device and does not diagnose, treat or prevent any condition.
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