When you’re shopping for seafood, species matters. Not just generic types (white fish, oily fish, shellfish) but actual species. The difference between similar species can be significant.
The seafood consumption chart published by the FDA and the EPA groups dozens of fish and shellfish into 3 categories based on mercury content. The serving counts are written for people who are pregnant or might become pregnant and for those who are nursing. Children aged 1 to 11 are handled separately: 2 servings a week from the Best Choices group only, in smaller portions that scale with age. The “Choices to Avoid” group is part of that same advice rather than a blanket ban for every adult. Those serving counts aren’t a rule for every adult, but the order of the groups is useful to anybody. Mercury content also varies from one fish to the next, so the chart reflects an average.
1. Canned Tuna
Healthiest: Canned Light Tuna, Including Skipjack
Unhealthiest: Albacore, or White Tuna
Canned light tuna: Skipjack is the main fish in canned light tuna, and FDA sampling puts canned light tuna as a category at 0.126 parts per million of mercury. That figure covers the product rather than the species; fresh and frozen skipjack is listed separately at 0.144 ppm, from only three samples. That puts it in the least-restricted group on the chart. It’s not the canning that makes a difference, it’s the type of tuna.
“Premium” doesn’t tell you whether you’re buying light tuna or albacore.
Albacore tuna: White albacore tuna is considered a step up from light tuna and costs more. But on mercury, white albacore is a step down: it contains about 3 times as much as light tuna and falls into a lower category on the chart. In FDA sampling albacore averages 0.350 parts per million.
You can give tuna a break occasionally and make the same lunch with canned salmon.
2. Mild White Fish
Healthiest: Cod
Unhealthiest: Orange Roughy
Cod: Cod and orange roughy are both mild-flavored white fish with a similar color and flavor. Cod is in the least-restricted group on the chart, at 0.111 ppm of mercury.
Orange roughy: Orange roughy has about 5 times as much mercury as cod, at 0.571 ppm, and it’s in the third group, the ones to skip.
3. Mackerel
Healthiest: Atlantic Mackerel
Unhealthiest: King Mackerel
Atlantic mackerel: According to data from the National Institutes of Health Office of Dietary Supplements, 3 oz of cooked Atlantic mackerel provides 0.59 g of DHA and 0.43 g of EPA. It’s in the least-restricted group on the chart too.
King mackerel: These two fish have little in common except for their first names. Don’t make the mistake of picking up a package of king mackerel thinking it’s Atlantic mackerel. King mackerel sits in the FDA’s “Choices to Avoid” group. Atlantic mackerel has 0.05 ppm mercury, king mackerel 0.73. Although both are included on the same FDA/EPA chart, the data for Atlantic mackerel is from a National Marine Fisheries Service report published in 1978 and the data for king mackerel is from a report on Gulf of Mexico seafood published 22 years later.
4. Fish for the Grill
Healthiest: Salmon
Unhealthiest: Swordfish
Salmon: It’s pretty obvious from the chart that the winner here is salmon. It contains 0.022 ppm of mercury, which puts it in the least-restricted column, and both farmed and wild do well there. According to the same NIH data, 3 oz of cooked farmed Atlantic salmon contains 1.24 g of DHA and 0.59 g of EPA, while 3 oz of cooked wild salmon contains 1.22 g of DHA and 0.35 g of EPA. So in that particular comparison the farmed fish has slightly more omega-3s than the wild one. It is one pair of numbers for Atlantic salmon rather than a rule about farmed versus wild: the omega-3 content of farmed fish tracks what they are fed, and it has fallen as vegetable oils replaced fish oil in feed.
Swordfish: Swordfish contains 0.995 ppm of mercury, which is a whopping 45 times salmon, so it’s on the skip list. That’s unfortunate, because it holds its shape on a grill, it has a wonderful texture, it’s high in protein, and its taste is beyond reproach. The mercury is the only thing wrong with it.
5. Tuna Steaks
Healthiest: Yellowfin Tuna
Unhealthiest: Bigeye Tuna
Yellowfin tuna: Yellowfin tuna steak falls into the middle of the chart, which makes it the better of the two without making it one of the lowest-mercury fish.
Bigeye tuna: Bigeye is on the skip list. Yellowfin is backed up by 231 samples whereas bigeye only has 21 samples to go on, so the grouping carries more weight than the two averages side by side. It’s also unclear which tuna steak you’re getting without asking.
6. Frozen Fish
Healthiest: Plain Frozen Pollock Fillets
Unhealthiest: Beer-Battered Pollock Fillets
Plain frozen pollock: Pollock sits in the first column of the chart. From a nutrition perspective it’s better to grab the plain frozen fillets and prepare them in a manner of your choosing, thereby determining how much fat and salt to add. Fish is recommended at least twice weekly by the American Heart Association in their 2018 science advisory, as long as it’s not fried. They go on to say that oilier fish are preferred.
Beer-battered pollock: Take a look at the Nutrition Facts label for Gorton’s 6-count Beer Battered Fillets. One serving of 2 fillets has 230 calories, 460 mg sodium, 9 g of protein, 10 g of fat and 27 g of carbohydrate. Even if they’re baked, the wheat and milk from the batter are still in there, as the allergen statement says: pollock, wheat and milk.
The standard Beer Battered pack lists 240 calories, 450 mg sodium and 10 g of protein for a slightly smaller serving.
They can still make a convenient dinner. Just compare the whole product rather than letting “wild-caught fish” on the front of the box settle the question.
7. Smoked Fish, for Adults 65 and Older
Healthiest: Shelf-Stable Canned Smoked Salmon
Unhealthiest: Refrigerated Smoked Salmon Eaten Cold
Shelf-stable canned smoked salmon: If you’re over the age of 65, the shelf-stable canned version is the better option. Older adults, defined by the CDC as those who are 65 and over, are more susceptible to certain types of foodborne illness than younger adults, namely Listeria. Shelf-stable canned fish has been heated enough to kill any bad guys before being sealed and doesn’t need to be refrigerated, which is why the CDC specifically mentions shelf-stable smoked fish for those who are older. That has nothing to do with the sodium or the nutritional value.
Use it in a sandwich, flake it over potatoes, or serve it with crackers and cucumber. Follow the package’s refrigeration instructions once you open it.
Refrigerated smoked salmon: Refrigerated smoked salmon, on the other hand, could contain Listeria, since the cold smoking process hasn’t heated it enough to kill pathogens. That doesn’t apply when it’s cooked into a dish, since heat kills Listeria. The caution isn’t about age alone, either: the CDC directs it at pregnant women, adults 65 and older, and anyone with a weakened immune system.
All 14 Choices at a Glance
| Category | Healthiest in this comparison | Unhealthiest in this comparison | Deciding factor |
|---|---|---|---|
| Canned tuna | Canned light tuna, including skipjack | Albacore tuna | Mercury |
| Mild white fish | Cod | Orange roughy | Mercury |
| Mackerel | Atlantic mackerel | King mackerel | Mercury |
| Fish for grilling | Salmon | Swordfish | Mercury, plus salmon’s omega-3 contribution |
| Tuna steaks | Yellowfin | Bigeye | Mercury; yellowfin still isn’t a lowest-mercury choice |
| Frozen fish | Plain pollock fillets | Beer-battered pollock fillets | Coating, seasoning and finished-product nutrition |
| Smoked fish, adults 65+ | Shelf-stable canned smoked salmon | Refrigerated smoked salmon eaten cold | Food safety |
Species matters more than the adjectives printed on cartons and containers. That’s where terms like fresh, line-caught, premium and wild come into play: they’re nice and they make you feel good, but you’re not being told which type of fish it is.
Next on the list of what to look for are added ingredients, especially in the case of frozen fish, followed by how it’s going to be cooked.
Cory Jones has spent 20 years in media and publishing and now leads the data and editorial operation behind The Greenest.
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