Fatty fish like mackerel, salmon, herring, and sardines are the richest natural sources of omega-3 fatty acids. A single 3.5-ounce serving of Atlantic mackerel delivers about 2,500 mg of the two omega-3s that matter most for your health: EPA and DHA. Most health organizations recommend eating fatty fish at least twice a week to get enough of these fats, which lower triglycerides, reduce inflammation, and support heart and brain function.
The Highest-Omega-3 Fish, Ranked
Not all fish are created equal. Cold-water, oily species pack dramatically more omega-3s than lean white fish. Here’s how the top choices compare per 3.5-ounce (100 g) raw serving, measured as combined EPA and DHA:
- Atlantic mackerel: 2,500 mg (900 mg EPA, 1,600 mg DHA)
- King mackerel: 2,200 mg (1,000 mg EPA, 1,200 mg DHA)
- Atlantic salmon, farmed: 1,800 mg (600 mg EPA, 1,200 mg DHA)
- Pacific herring: 1,700 mg (1,000 mg EPA, 700 mg DHA)
- Atlantic herring: 1,600 mg (700 mg EPA, 900 mg DHA)
- Chinook (king) salmon: 1,400 mg (800 mg EPA, 600 mg DHA)
- Sockeye salmon: 1,200 mg (500 mg EPA, 700 mg DHA)
- Sardines, canned: 1,000 mg (400 mg EPA, 600 mg DHA)
For context, a single serving of Atlantic mackerel gives you more than a full day’s worth of omega-3s by most guidelines. Even the lower-ranking options on this list, like canned sardines, still deliver a substantial dose.
Shellfish as an Omega-3 Source
If you’re not a fan of oily fish, shellfish can fill part of the gap. Pacific oysters provide about 690 mg of combined EPA and DHA per 3.5-ounce serving. Shrimp comes in at roughly 480 mg and blue mussels at 440 mg. These aren’t as concentrated as salmon or mackerel, but they’re still meaningful sources, especially if you eat them regularly. Oysters have the added bonus of being extremely rich in zinc and vitamin B12.
Why EPA and DHA Matter
Fish contain two specific types of omega-3 fats: EPA and DHA. These are the forms your body actually uses. Plant sources like flaxseed and walnuts contain a different type called ALA, which your body converts to EPA and DHA very inefficiently, typically at rates below 10%.
EPA and DHA lower triglyceride levels in the blood, raise HDL (good) cholesterol, and reduce inflammatory markers throughout the body. They also improve the flexibility of artery walls, which helps blood flow more freely. DHA is a major structural component of brain tissue and the retina, which is why it’s considered especially important during pregnancy and early childhood development.
Wild vs. Farmed Salmon
This is one of the most common questions people have, and the answer is more nuanced than most articles suggest. Farmed Atlantic salmon and wild Atlantic salmon contain nearly identical amounts of DHA per 3-ounce cooked serving: about 1.24 g for farmed and 1.22 g for wild. The EPA content differs more, with farmed salmon providing roughly 590 mg and wild salmon about 350 mg.
The reason farmed salmon keeps pace is simple: farmed fish are fattier overall, so even though a smaller percentage of their fat is omega-3, the total amount stays comparable. Modern fish feeds are formulated with enough fish oil to maintain omega-3 levels equivalent to or higher than most wild fish. Wild salmon get their omega-3s from the algae and plankton in their natural diet, which means the exact amounts vary by species and season. Both are excellent choices for omega-3 intake.
Mercury: Which Fish Are Safest
The best omega-3 fish also tend to be among the lowest in mercury. Sardines contain just 0.013 parts per million of mercury, and canned salmon comes in at 0.014 ppm. Anchovies (0.016 ppm), fresh salmon (0.022 ppm), and Atlantic mackerel (0.05 ppm) are all very low. Herring sits at 0.078 ppm, still well within safe limits for frequent consumption.
The fish to watch out for are king mackerel at 0.73 ppm and bigeye tuna at 0.689 ppm. These are large, long-lived predators that accumulate mercury over time. Canned light tuna (0.126 ppm) is a much safer option than canned albacore (0.350 ppm) if tuna is your preference. The general rule: smaller, shorter-lived fish are lower in mercury and often higher in omega-3s per ounce. Sardines, anchovies, herring, and salmon hit the sweet spot of high omega-3s and minimal contamination.
How Cooking Affects Omega-3 Content
Your cooking method makes a real difference in how much omega-3 you actually get from your fish. Steaming retains the most EPA and DHA of any method. Baking in foil performs nearly as well, since it traps moisture and limits fat loss. Grilling and deep-frying cause significant drops in omega-3 content. Deep-frying is the worst option: it not only destroys EPA and DHA but also increases omega-6 fats from the cooking oil, which can counteract some of the anti-inflammatory benefits.
Boiling results in moderate losses of around 7 to 8%, since some fat leaches into the cooking liquid. Microwaving causes losses similar to grilling, around 11%. If you’re eating fish specifically for omega-3s, steaming, poaching, or baking in parchment or foil will preserve the most nutritional value.
How Much Fish You Actually Need
Two servings of fatty fish per week is the standard recommendation from the American Heart Association. That works out to roughly 6 to 7 ounces total. If you choose high-omega-3 species like salmon, mackerel, or sardines, two servings easily provides 2,000 to 3,500 mg of EPA and DHA per week.
If you prefer milder fish like cod or tilapia, you’ll get far less. Tilapia, for example, contains only about 115 mg of combined EPA and DHA per serving. You’d need to eat roughly 15 servings of tilapia to match one serving of Atlantic mackerel. For people who eat fish occasionally but not twice a week, prioritizing the fattiest species when you do eat fish makes a noticeable difference in your overall intake.