Choosing The Right Seafood For Optimal Health

If you’ve been following a gut- and brain-healthy diet — Mediterranean, pescatarian, or something close — you already know fish should be one of your main protein sources. Aim for two to three servings per week, which works out to roughly a quarter of your total protein intake, replacing most red meat.

And my advice: eat it without the anxiety about toxins. The benefits outweigh the risks if you choose well.

Oily fish — salmon, tuna, sardines, mackerel, anchovies — are where you get your omega-3 fatty acids (also called n-3s or polyunsaturated fatty acids PUFAs). These matter. A higher ratio of n-6 to n-3 in the diet tends to drive inflammation; a more balanced ratio works against it. Omega-3s also promote neurogenesis in the dentate gyrus of the hippocampus, and there’s a meaningful correlation between omega-3 intake and hippocampal-dependent memory. In the traditional Western diet, we’re eating PUFAs at roughly a 16:1 ratio of n-6 to n-3. Our ancestors ate something closer to 1:1. That gap has consequences.

How much omega-3 do you actually need? The American Heart Association recommends 250–500 mg of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) combined per day for healthy adults — and up to 1,000 mg for those with cardiovascular disease. Keep those numbers in mind as you read through the fish profiles below; they’ll make the milligram figures meaningful rather than abstract.

The smallest fatty fish — sardines especially — have the highest omega-3 concentrations because they eat omega-3-rich algae directly. Larger fish like salmon get their omega-3s by eating those smaller fish. So the food chain actually works in your favor here, as long as you’re picking the right species.

Two other factors matter beyond omega-3 content: contaminant levels (mercury and PCBs in particular) and whether the fishery is sustainable. Fortunately, you don’t have to work this out yourself. Programs like Seafood Watch, run by the Monterey Bay Aquarium, and the Blue Ocean Institute have already cross-referenced health data from organizations like the Environmental Defense Fund with environmental impact data. Their lists do the homework for you.

A note on cooking method. How you prepare fish affects how much omega-3 benefit you actually get. Frying — especially in vegetable or seed oils high in n-6 fatty acids — partially offsets the anti-inflammatory advantage you’re eating fish for in the first place. Baking, broiling, steaming, or eating fish cold (as in canned) preserves omega-3 content better. Canning itself doesn’t meaningfully reduce omega-3 levels, though canned fish can be high in sodium — worth watching if that’s a concern for you.

A note for pregnant women and young children. Mercury risk is not uniform across the population. The FDA specifically advises pregnant women, those who may become pregnant, breastfeeding mothers, and young children to avoid high-mercury fish entirely and to limit overall fish consumption to 2–3 servings per week from lower-mercury options. The “avoid” list later in this article overlaps significantly with the FDA’s high-mercury list. If you’re in this group, the choice of species matters even more than it does for the general population.

Six Fish Worth Eating Regularly

The following is adapted from a blog by Brierley Wright, published by One Medical.

Farmed oysters. A 3-ounce serving has over 300 mg of omega-3s and about a third of the daily recommended iron. Oysters also filter the water they live in, feeding on natural algae and nutrients — which is part of why they’re one of the more environmentally benign animal proteins you can buy.

Wild-caught Pacific sardines. The most omega-3-dense food on this list: 1,950 mg per 3-ounce serving. More than salmon. They’re also naturally high in vitamin D, which few foods are. Sardines reproduce quickly, which is why Pacific sardines have managed to rebound even after overfishing and a population collapse in the 1940s. Canned sardines are a perfectly good option — the omega-3 content holds up, and they’re one of the more affordable ways to hit your daily target.

Wild-caught Alaska salmon. Alaska’s fishery is tightly managed — if returning salmon numbers drop, the fishery closes before reaching quota limits. That level of oversight means these fish carry fewer contaminants than most salmon on the market, and they deliver 1,210 mg of omega-3s per 3-ounce serving.

Farmed freshwater coho salmon. The only farmed salmon to earn a “Super Green” rating from Seafood Watch. Most farmed salmon is still on the “Avoid” list: crowded open-net pens lead to parasite and disease problems, and it can take up to three pounds of wild fish to produce one pound of farmed salmon. Coho raised in closed freshwater systems sidestep most of those issues and provide 1,025 mg of omega-3s per serving.

Farmed rainbow trout. Almost all the trout in US markets is farmed rainbow trout, raised in freshwater ponds and raceways. The controlled environment limits contaminant exposure, and the feed has been refined to reduce waste.

Troll- or pole-caught albacore tuna (US or British Columbia). Most tuna are high in mercury, but smaller, younger albacore caught by troll or pole — rather than longlining — have significantly lower mercury and contaminant levels, and often higher omega-3 counts from colder northern waters. Look for the Marine Stewardship Council (MSC) blue label if you’re not sure how your tuna was caught. Canned white tuna is typically albacore — just check that it specifies “pole-” or “troll-caught” on the label or carries the MSC certification.

Six Fish Worth Avoiding

Several popular fish are both ecologically depleted and high in contaminants. These six come up repeatedly.

Bluefin tuna. Listed by the World Wildlife Fund as a threatened species alongside giant pandas and leatherback turtles. Mercury levels are high, and the Environmental Defense Fund recommends avoiding it entirely due to PCB concentrations — despite the fact that individual fish can sell for over $177,000.

Chilean sea bass (Patagonian toothfish). Slow-growing and slow to recover from overfishing pressure. The trawling and longlining methods used to catch it have also damaged ocean floor habitats and killed seabirds. The EDF has issued a mercury advisory.

Grouper. Can live to 40 years but has a short reproductive window, making it slow to recover from fishing pressure. EDF mercury advisory in effect.

Monkfish. Recovering from past depletion but trawling for it still damages the bottom habitat it depends on.

Orange Roughy. Lives over 100 years, which means it accumulates mercury over a very long time. The fish in your freezer may well be older than your grandmother. EDF health advisory issued.

Farmed Atlantic salmon. Nearly all salmon labeled “Atlantic salmon” is farmed in open-net pens, where parasites, disease, and antibiotic use are ongoing problems. PCB levels are high enough to warrant an EDF health advisory. Freshwater-farmed coho is the exception.

One more to know about: US freshwater fish. A study published in Environmental Research found that a single serving of freshwater fish caught from US lakes and rivers could expose you to per- and polyfluorinated substances (PFAS) — so-called forever chemicals — at levels equivalent to a month of drinking water contaminated 2,400 times above EPA health advisories. Locally caught freshwater fish showed far higher PFAS levels than commercial catches.

Reading Labels at the Fish Counter

Labels can be misleading, and a few things are worth knowing before you shop. “Wild-caught” is not always a reliable claim — it tells you nothing about the fishery’s sustainability or the fish’s contaminant levels. “Atlantic salmon” almost always means farmed, regardless of where it was purchased. “Fresh” often just means previously frozen and thawed. The most reliable signal is the MSC blue eco-label for wild-caught fish, or an ASC (Aquaculture Stewardship Council) label for farmed. Alternatively, Seafood Watch’s free app lets you search by species and see a current sustainability rating — it’s the easiest way to check in the moment.

The decision framework is simple: high omega-3s, low contaminants, sustainable sourcing. Most of the popular, expensive fish fail on at least two of those three counts. Small fatty fish, oysters, and wild-caught Alaskan salmon pass all three.