Is it better to buy wild or farmed? Should canned tuna be on the shopping list? Why does one mackerel turn up on recommended lists while another carries a mercury warning? Seafood is one of the few aisles where it is genuinely hard to know what the better choice is.
Most of it comes down to 3 things. The type of fish, what has been added to it, and the way it is prepared.
What follows is 7 common choices, each one a pair. Healthiest and unhealthiest refer to the stronger and weaker option inside that pair, for the reason given there. They are not an attempt to rank every fish in the sea. Albacore tuna can belong in a healthy diet even though another canned tuna has the advantage on mercury.
One thing applies throughout. The chart the FDA and EPA publish together is written for people who might become pregnant, are pregnant or breastfeeding, and children aged 1 to 11. Its serving counts are not a rule for every adult. The way it groups fish by mercury is useful shopping information for anybody.
1. Canned Tuna
Healthiest: Canned Light Tuna, Including Skipjack
Unhealthiest: Albacore, or White Tuna
Canned light tuna: Light tuna, which may be skipjack, is part of the FDA’s Best Choices grouping. In FDA sampling between 1991 and 2010, canned light tuna had a mean mercury level of 0.126 parts per million across 545 samples.
For lunch, light tuna does everything you need it to do. Mash it with lemon, a little mayonnaise, chopped celery, and whatever herbs are surviving in the fridge. Put it in a sandwich or pile it onto white beans.
Check the actual fish description. “Premium” doesn’t tell you whether you’re buying light tuna or albacore.
Albacore tuna: Albacore, sold as white tuna, sits in the Good Choices category instead. FDA sampling between 1991 and 2009 put canned albacore at a mean of 0.350 parts per million across 451 samples, roughly 2.8 times canned light. The difference has nothing to do with canning, since both are canned, and nothing to do with albacore losing nutritional value. It is mercury.
If tuna is a frequent lunch, the species deserves more attention than the fancy packaging. You can also give tuna a break occasionally and make the same lunch with canned salmon.
2. Mild White Fish
Healthiest: Cod
Unhealthiest: Orange Roughy
Cod: Cod is in the FDA’s Best Choices group. In FDA sampling between 1991 and 2010 it had a mean of 0.111 parts per million across 115 samples. Cod is also mild enough not to overpower a dish, which is probably why it turns up in so many recipes.
Cod works with tomatoes and olives, a little lemon and butter, or the same seasonings you’d put on roasted vegetables. For a simple dinner, bake it with cherry tomatoes, garlic, and olive oil, and serve it with bread for the juices. It doesn’t need much more.
Orange roughy: Orange roughy is in Choices to Avoid, the grouping for the fish carrying the most mercury. FDA samples collected between 1991 and 2009 gave it a mean of 0.571 parts per million across 81 samples, around 5 times cod. It is a white fish and it tastes fairly bland, so nothing about it at the counter gives away which category it belongs to. Both figures are averages across samples rather than a measurement of any particular fillet.
If a recipe calls for orange roughy, ask the fish counter about substituting cod. Adjust the cooking time for the thickness of the piece rather than assuming every white fillet cooks at the same speed.
3. Mackerel
Healthiest: Atlantic Mackerel
Unhealthiest: King Mackerel
Atlantic mackerel: Atlantic mackerel is an oily fish, and 3 ounces cooked carries 0.59 grams of DHA and 0.43 grams of EPA, according to the NIH Office of Dietary Supplements. It sits in the Best Choices column of the FDA’s chart.
Its rich flavor works especially well with something sharp. Think mustard, lemon, vinegar, or pickled onions. If you’re trying a tin for the first time, put it on toast with sliced cucumber and a squeeze of lemon. Start there before deciding you need an elaborate recipe.
King mackerel: King mackerel sits in the highest-mercury Choices to Avoid grouping. That one chart, applying a single method to both fish, is the firmest basis for telling them apart. The FDA’s mercury table puts Atlantic mackerel at a mean of 0.05 parts per million, from a 1978 report by the National Marine Fisheries Service, and king mackerel at 0.73, from a Gulf of Mexico report published in 2000. Those 2 reports span 22 years and come from different agencies, so the gap between the numbers is not apples-to-apples. Sharing the name mackerel does not make the 2 species the same fish.
At a counter or restaurant, ask which species you’re getting. A fish’s first name can change the decision.
4. Fish for the Grill
Healthiest: Salmon
Unhealthiest: Swordfish
Salmon: Salmon is in Best Choices on the FDA’s chart. The agency’s mercury table lists fresh or frozen salmon at a mean of 0.022 parts per million across 94 samples collected between 1991 and 2009. Farmed salmon sometimes gets a bad name, but the NIH Office of Dietary Supplements has farmed Atlantic salmon carrying slightly more of the marine omega-3s than wild. A 3-ounce cooked serving of farmed has 1.24 grams of DHA and 0.59 grams of EPA, against 1.22 grams of DHA and 0.35 grams of EPA for wild. Being farmed does not by itself put salmon on an unhealthy list.
Buy the version that suits your budget and the dish you want to make. For grilling, a skin-on piece gives you something sturdy to work with. Add lemon and herbs, or brush it with a little mustard.
Swordfish: Swordfish is in the Choices to Avoid grouping for the highest-mercury fish. Its mean in the same table is 0.995 parts per million across 636 samples collected between 1990 and 2010, about 45 times salmon. Swordfish is firm and flavorful and takes well to a range of preparations, and none of that is in question here. The difference in this pairing is mercury.
5. Tuna Steaks
Healthiest: Yellowfin Tuna
Unhealthiest: Bigeye Tuna
Yellowfin tuna: Yellowfin is categorized as Good Choices on the FDA’s chart. It is the better of this pair, which does not put it alongside a lowest-mercury fish such as salmon.
Ask the seller to identify the species. You don’t need to turn ordering dinner into an interrogation; one straightforward question will do.
Bigeye tuna: Bigeye is in Choices to Avoid, the grouping for the fish with the highest mercury levels. The mercury table is less useful than the chart in this case, because the bigeye mean rests on 21 samples against 231 for yellowfin, so the category assignment is the firmer ground. A restaurant menu may say tuna steak without naming either one. Price doesn’t tell you, color doesn’t tell you, and presentation doesn’t tell you.
If you eat seafood often, build some variety into the rotation rather than asking one favorite to cover every meal.
6. Frozen Fish
Healthiest: Plain Frozen Pollock Fillets
Unhealthiest: Beer-Battered Pollock Fillets
Plain frozen pollock: Pollock is in the FDA’s Best Choices category. A plain fillet leaves the coating and the seasoning entirely up to whoever cooks it. A 2018 science advisory from the American Heart Association supports eating non-fried seafood at least twice a week, with a nod toward the species higher in long-chain omega-3 fats.
A bag of plain fillets gives you options. Bake them with paprika and lemon, flake them into tacos, or add your own thin crumb topping. You decide how much coating and seasoning goes on.
Beer-battered pollock: Beer-battered fillets start as the same species and finish as a different food. A serving of 2 fillets, 108 grams, in the 6-count package of Gorton’s Beer Battered Fillets runs 230 calories, 460 milligrams of sodium, 9 grams of protein, 10 grams of total fat and 27 grams of carbohydrate. Its allergen line reads pollock, wheat and milk, and the wheat and the milk are the batter.
Those numbers belong to that one package. The standard pack of the same product lists 240 calories, 450 milligrams of sodium and 9 grams of protein for 2 fillets at 103 grams. Baking or air-frying removes nothing that went into the coating beforehand, which is why the ingredient list and the sodium line are worth reading even on fillets that look plain. Frozen fish products vary a great deal.
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: Which smoked fish is the better choice depends on 2 things, who is eating it and how it is going to be used. Adults over 65 are more susceptible to foodborne germs including Listeria. The CDC identifies shelf-stable smoked fish as the safer choice for them, because it has been treated with heat that kills germs and sealed so that it needs no refrigeration until it is opened.
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: Smoked seafood from the refrigerated case is the riskier choice for that group, unless it goes into a cooked dish. Cold smoking involves no heat treatment that would kill Listeria, and a sealed packet from the chiller is not the same product as a shelf-stable can. None of this is a statement about nutrition, and shelf-stable does not mean lower sodium or a better food. For readers outside that age group, refrigerated smoked salmon is not an intrinsically bad option.
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 first, then what has been added to it, then how it is going to be served. That order settles more than the biggest word on the package does.
Wild, premium and fresh all sound reassuring, and none of them answers every question that matters.
Cory Jones has spent 20 years in media and publishing and now leads the data and editorial operation behind The Greenest. He built and maintains the site’s Neighborhood Wellness Score — a proprietary dataset scoring food access, walkability, air quality, healthcare access, and health outcomes across 18,356 U.S. ZIP codes, drawing on CDC PLACES data, EPA air quality readings, and verified location intelligence. He turned 50 last year, is a huge fan of Rancho Gordo beans, and tries to work out more than he actually works out.
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