The healthiest fish to eat are fatty, cold-water species like salmon, mackerel, and sardines, which pack the most omega-3 fatty acids per serving while staying low in mercury. But the best choice for you depends on what you’re optimizing for: heart-healthy fats, lean protein, low contaminants, or all three. The U.S. Dietary Guidelines recommend at least 8 ounces of seafood per week, and the type you choose matters as much as the amount.
Why Fatty Fish Tops the List
The omega-3 fatty acids EPA and DHA are the main reason fish earns its reputation as a health food. Your body can’t make these efficiently on its own, so you need them from food. They reduce inflammation, support brain function, and lower the risk of heart disease. A study published in Circulation found that people who ate non-fried fish at least twice a week had roughly half the risk of dying from heart disease compared to people who rarely ate fish, after adjusting for other dietary and health factors.
Not all fish contain meaningful amounts of these fats. Atlantic mackerel delivers about 2.5 grams of combined EPA and DHA per 100-gram serving (roughly 3.5 ounces), making it one of the richest sources available. Farmed Atlantic salmon comes in around 1.8 grams. Sardines provide about 1 gram. By contrast, lean white fish like cod contains only trace amounts. If omega-3s are your goal, fatty fish wins by a wide margin.
The Best All-Around Choices
Several fish score well across nutrition, safety, and sustainability. Here are the strongest options:
- Salmon (wild or farmed): The most popular fatty fish for good reason. Sockeye and chinook varieties are rich in omega-3s, and even farmed Atlantic salmon matches or exceeds wild salmon’s omega-3 content because farmed fish carry more total fat. Both wild and farmed salmon are low in mercury and PCBs.
- Sardines: A nutritional powerhouse in a tiny package. Because you eat them bones and all, canned sardines are an excellent source of calcium. A 3.5-ounce serving provides about 330 IU of vitamin D, covering more than half the daily recommendation. They’re also near the bottom of the food chain, which means minimal mercury accumulation.
- Atlantic mackerel: The omega-3 champion, with more EPA and DHA per serving than any common fish. One important distinction: Atlantic mackerel is a “best choice” for mercury, but king mackerel is on the FDA’s avoid list due to high mercury levels. Always check which species you’re buying.
- Rainbow trout (U.S. farmed): A solid middle ground with good omega-3 levels and very low contamination. The Monterey Bay Aquarium’s Seafood Watch program lists it as a top sustainable choice.
- Anchovies: Similar to sardines in profile. Small, oily, bone-in, and loaded with micronutrients. Their strong flavor means a little goes a long way in sauces and dressings.
When Lean Fish Makes More Sense
Fatty fish gets most of the attention, but lean white fish like cod, pollock, and sole have their own advantages. A 3-ounce cooked serving of Atlantic cod delivers nearly 20 grams of protein for just 89 calories. That protein-to-calorie ratio is hard to beat if you’re watching your weight or simply want a lighter meal. These fish are also good sources of iodine, selenium, and vitamin B12.
The trade-off is straightforward: you get far less omega-3. If you already take a fish oil supplement or eat fatty fish a couple of times a week, lean fish fills the remaining spots in your diet nicely. Alaska flounder and sole appear on the Seafood Watch sustainability list, making them a responsible choice as well.
Mercury: What Actually Matters
Mercury is the main safety concern with fish, and it accumulates more in large, long-lived predators. The FDA divides fish into three categories based on average mercury concentration. “Best choices” contain 0.15 parts per million or less, and you can safely eat two to three servings a week. “Good choices” fall between 0.15 and 0.46 ppm, and should be limited to one serving per week. Fish above 0.46 ppm should be avoided entirely.
The fish to avoid are shark, swordfish, king mackerel, tilefish from the Gulf of Mexico, bigeye tuna, marlin, and orange roughy. Everything on the “best all-around” list above falls comfortably in the lowest mercury category. If you’re pregnant or breastfeeding, the FDA recommends 8 to 12 ounces per week from the “best choices” category, using a 4-ounce serving size.
Farmed vs. Wild: Less Drama Than You’d Think
The farmed-versus-wild debate has cooled significantly in recent years. Early studies flagged higher PCB levels in farmed salmon, but follow-up research hasn’t confirmed those findings consistently. The Washington State Department of Health notes that the scientific consensus now considers both farmed and wild salmon safe, with low levels of mercury, PCBs, and other contaminants in both.
Nutritionally, farmed salmon is fattier overall, which means it often contains as much or more omega-3 as wild salmon per serving. Wild salmon tends to be leaner and slightly higher in certain minerals. The practical difference is small enough that eating whichever is available and affordable serves you well. One thing worth knowing: as farmed fish feeds have shifted toward more plant-based ingredients, some farmed fish contain slightly less omega-3 than they used to, though producers generally maintain levels comparable to wild fish.
Sustainability Worth Considering
The Monterey Bay Aquarium’s Seafood Watch program rates fish on environmental impact, and their “Super Green” list highlights species that are both nutritious and sustainably sourced. The top picks include farmed mussels, pole-caught albacore tuna, U.S. farmed rainbow trout, Alaska flounder, U.S. farmed catfish, farmed clams, Arctic char, and farmed oysters. Several of these overlap with the nutritional standouts, which makes the choice easier.
Mussels and oysters deserve special mention. They’re filter feeders that actually improve water quality where they’re grown, and they’re rich in iron, zinc, and B12. Oysters in particular are one of the best dietary sources of zinc available. They don’t provide as much omega-3 as fatty fish, but their overall micronutrient density is exceptional.
How You Cook It Changes the Nutrition
Preparation method has a real effect on how much omega-3 you actually absorb. Steaming retains the most EPA and DHA, with studies showing 50 to 60 percent retention of omega-3s in certain fish species. Baking in foil performs reasonably well too, preserving roughly 35 to 40 percent. Deep frying and grilling at high heat cause the most nutrient loss, and breaded, fried fish sandwiches have been linked to none of the heart benefits seen with non-fried fish in cardiovascular research.
The simplest approach: bake, steam, or poach your fish. A piece of salmon baked at 400°F for 12 to 15 minutes with olive oil, salt, and lemon retains far more of what makes it healthy than the same fillet battered and fried. Canned fish like sardines and salmon are already cooked gently during processing and retain their nutrients well, making them one of the most convenient options available.
Putting It Together
If you eat fish twice a week, making one of those meals a fatty fish like salmon, sardines, or mackerel covers your omega-3 needs and delivers meaningful protection against heart disease. Fill the second meal with whatever you enjoy, whether that’s a lean white fish, shrimp, or shellfish. Vary your choices to spread out any trace contaminant exposure and broaden your nutrient intake.
For people who don’t like the taste of fish, canned sardines mashed into pasta sauce or canned salmon mixed into patties can be easier entry points than a plain fillet. Small, inexpensive, low-mercury fish like sardines and anchovies are arguably the single best value in nutrition: high omega-3s, calcium from the bones, vitamin D, and virtually no mercury risk, all for a couple of dollars per can.