Atlantic mackerel and salmon are among the fish highest in omega-3 fatty acids, but the single highest concentration belongs to a deep-water lake trout called siscowet, which packs about 3.0 grams of combined EPA and DHA per 100 grams of fish. For most people shopping at a grocery store, Atlantic mackerel, salmon, herring, and sardines are the richest and most accessible options.
The Top Fish Ranked by Omega-3 Content
Omega-3 levels vary dramatically between species. The two forms that matter most for health are EPA and DHA, both found primarily in fatty, cold-water fish. Here’s how the top species compare per 100 grams of raw, edible fish, based on data from Oregon State University:
- Lake trout (siscowet): 3.0 g total EPA + DHA
- Atlantic mackerel: 2.5 g
- King mackerel: 2.2 g
- Chub mackerel: 1.9 g
- Farmed Atlantic salmon: 1.8 g
Siscowet is a subspecies of lake trout found in the deep waters of Lake Superior. It’s exceptionally fatty, which explains its omega-3 lead. You won’t find it in most grocery stores, though. For everyday shopping, Atlantic mackerel and salmon are the practical winners.
Common Grocery Fish Compared
Per 3-ounce cooked serving (about the size of a deck of cards), here’s what you actually get from fish you can buy at most stores, according to NIH data:
- Farmed Atlantic salmon: 1.83 g EPA + DHA
- Wild Atlantic salmon: 1.57 g
- Atlantic herring: 1.71 g
- Sardines (canned): 1.19 g
- Rainbow trout (wild): 0.84 g
- Sea bass: 0.65 g
- Canned light tuna: 0.19 g
- Tilapia: 0.15 g
- Cod: 0.14 g
The gap between the top and bottom of this list is striking. A single serving of farmed salmon delivers more than 12 times the omega-3s of the same amount of cod. Lean white fish like tilapia and cod are healthy protein sources, but they’re poor choices if omega-3s are your goal.
Farmed salmon actually edges out wild salmon in total omega-3 content. This surprises many people, but farmed salmon are fattier overall because they’re less active and eat a controlled, high-fat diet. Wild salmon tends to be leaner, with slightly less DHA per serving.
Shellfish and Other Seafood
Shellfish generally contain far less omega-3 than oily fish, but mussels and oysters are worth mentioning. A 3-ounce serving of either provides roughly 500 to 1,000 mg of combined EPA and DHA. That puts them in the same range as rainbow trout and well above shrimp, scallops, and crab, which deliver under 250 mg per serving. If you don’t love fish but enjoy shellfish, mussels are your best bet.
Fish Roe Is Surprisingly Rich
Fish eggs are one of the most concentrated natural sources of omega-3s. Salmon roe contains roughly 24% DHA and 7% EPA by fat content, and herring roe is even higher in EPA at nearly 14%. These percentages are significantly higher than what you find in the muscle meat of the same fish. A small serving of salmon roe or caviar can deliver a meaningful omega-3 dose, making it a useful option if you eat fish infrequently but want to boost your intake.
Mercury Concerns With High-Omega Fish
Some of the fish highest in omega-3s are also high in mercury, so the best choice isn’t always the one with the most omega-3 per gram. King mackerel, swordfish, and fresh bluefin or bigeye tuna all carry high mercury levels. These are fish to limit, especially for pregnant women and young children.
The sweet spot is fish that are both high in omega-3s and low in mercury. California’s Office of Environmental Health Hazard Assessment identifies six species that fit this profile: anchovies, herring, canned mackerel, salmon (canned or fresh), sardines, and trout. These are the species you can eat frequently without worrying about mercury accumulation. Atlantic mackerel in canned form falls in the low-mercury category, while king mackerel does not.
Cooking Methods Affect Omega-3 Levels
How you prepare fish changes how much omega-3 you actually end up eating. Heat breaks down EPA and DHA, and higher temperatures cause greater losses. Steaming at 100°C preserves roughly 55 to 60% of the original EPA content, while baking in foil at 160°C retains only about 37%. Grilling and deep-frying perform even worse.
Steaming also preserves more of the fish’s weight. Steamed fillets retain about 85% of their original mass, meaning less moisture and fat drip away during cooking. If maximizing omega-3 intake matters to you, steaming is the best cooking method, followed by baking in foil. Deep-frying is the worst, and adding vegetable oil during frying can actually dilute the omega-3 concentration with less beneficial fats.
Canned fish like salmon and sardines are typically cooked at lower temperatures during processing and sealed with their own oils, which helps preserve omega-3 content. Canned options are also inexpensive and shelf-stable, making them one of the most practical ways to eat omega-3-rich fish regularly.
How Much You Actually Need
Most health organizations recommend at least two servings of fatty fish per week. Two 3-ounce servings of salmon would give you roughly 3.6 grams of EPA and DHA for the entire week, or about 500 mg per day. That aligns with the intake level most commonly associated with cardiovascular benefits in large studies.
If you’re choosing lower-omega species like canned light tuna or shrimp, you’d need to eat them far more often to reach the same levels. A single serving of salmon delivers as much omega-3 as roughly ten servings of canned light tuna. For most people, eating salmon, mackerel, herring, or sardines once or twice a week is the simplest path to adequate omega-3 intake without supplements.