What Is the Healthiest Fish According to Dietitians?

October 31, 2025 •

4 min read

According to the American Heart Association, eating fish at least two times per week is recommended for heart health. But with so many options available, figuring out what is the healthiest fish according to dietitians can be confusing. The answer often points toward small, oily fish that provide essential nutrients while keeping mercury intake low.

Quick Summary

Dietitians recommend prioritizing small, oily fish such as salmon, sardines, and mackerel for their high omega-3 fatty acids and lower mercury levels. Balancing these with leaner white fish like cod and focusing on sustainable, properly cooked options helps build a nutritious and balanced diet.

Key Points

Small Oily Fish are Top Tier: Sardines, salmon, and mackerel are consistently recommended for their high levels of omega-3 fatty acids (EPA and DHA) and low mercury content.
Low Mercury is Key: Smaller fish that are lower on the food chain, such as sardines and Atlantic mackerel, accumulate less mercury, making them a safe choice for regular consumption.
Wild vs. Farmed Differences: Both wild and responsibly sourced farmed salmon offer excellent omega-3 content, but consumers should look for certifications like ASC or MSC to ensure sustainable practices.
Lean White Fish are Great Protein: For those seeking low-calorie, high-protein options, lean white fish like cod, haddock, and pollock are highly nutritious, though lower in omega-3s.
Check for Certifications: Opting for certified sustainable seafood (MSC, ASC) is a conscientious way to support environmental health and fish populations.
Choose Healthy Cooking Methods: To maximize health benefits, prepare fish by baking, grilling, or steaming rather than frying.
Limit High-Mercury Species: Reduce intake of larger predatory fish like king mackerel, shark, and swordfish to minimize mercury exposure.

Prioritizing Omega-3 Rich, Low-Mercury Fish

Dietitians and nutrition experts consistently champion fish for its numerous health benefits, with a clear preference for species that offer high levels of omega-3 fatty acids (EPA and DHA) and minimal mercury contamination. These fatty acids are crucial for brain and heart health, helping to lower blood pressure, reduce inflammation, and decrease the risk of cardiovascular disease. For most consumers, the healthiest choices lie within the category of smaller, oily fish, which are lower on the food chain and therefore accumulate less mercury.

Oily Fish: The Top Tier for Omega-3s

When it comes to packing a powerful omega-3 punch, certain oily fish rise to the top. They are not only rich in healthy fats but also provide significant amounts of protein and other essential vitamins and minerals.

Salmon: The Popular Powerhouse

Salmon is arguably the most well-known healthy fish, celebrated for its robust flavor and high omega-3 content. Both wild and farmed varieties offer excellent nutrition, but there are differences to consider. Wild salmon often has a slightly leaner profile and contains fewer contaminants, while some farmed varieties, depending on their feed, can have higher fat and omega-3 levels. When choosing farmed salmon, look for certifications like the Aquaculture Stewardship Council (ASC) label, which indicates responsible farming practices. A 3-ounce serving of wild sockeye salmon can provide over 2,200 mg of omega-3s, easily exceeding daily recommendations.

Sardines: Tiny Titans of Nutrition

Often overlooked, sardines are a superfood powerhouse. Because they are small and short-lived, they have very low mercury levels. They are exceptionally high in omega-3s, and when consumed from the can with their soft bones, they are also one of the best dietary sources of calcium and vitamin D. A single can can provide over 20 grams of protein and meet a significant portion of your daily calcium needs. They are also a budget-friendly and shelf-stable option.

Mackerel and Herring: Heart-Healthy Alternatives

Atlantic and Pacific chub mackerel are excellent sources of omega-3s and vitamin B12, and contain lower mercury levels than larger king mackerel. Herring is another staple of the Nordic diet and provides high levels of omega-3s, vitamin D, and selenium. Both can be found fresh, canned, or pickled.

The Lean and Healthy White Fish

For those who prefer a milder flavor and lower-fat protein, lean white fish are a fantastic choice. While lower in omega-3s than their oily counterparts, they are still highly nutritious.

Cod: A classic mild-flavored fish, cod is a great source of lean protein, B vitamins, and potassium. Its low fat content makes it low in calories, and it's a good entry point for those new to fish.
Haddock: Similar to cod, haddock is a mild, flaky white fish that is high in protein and low in fat. It's often used in British fish and chips.
Pollock: A common whitefish, Alaskan pollock is known for its mild flavor and sustainable fishing methods. It offers solid protein with low mercury levels.

Navigating Mercury Levels

Mercury is a naturally occurring element that can accumulate in fish, particularly larger, longer-living predatory species. For the general population, mercury in fish is not a major concern, but it's important to choose lower-mercury options, especially for pregnant women, breastfeeding mothers, and young children. High-mercury fish to limit or avoid include king mackerel, shark, swordfish, and bigeye tuna. The FDA and EPA provide guidance, classifying many commonly consumed fish, like salmon and sardines, as 'Best Choices' for their low mercury content.

Comparing Healthy Fish Options

To help you decide what to include in your nutrition diet, here is a comparison of some popular healthy fish options:


Fish Type	Omega-3 Level (high/medium)	Mercury Level (low/high)	Key Nutrients	Best For
Sardines	High	Low	Calcium, Vitamin D, B12	High-nutrient, budget-friendly option
Wild Salmon	High	Low	Protein, Vitamin D, Selenium	Excellent all-around option
Mackerel (Atlantic/Pacific)	High	Low	Protein, B12, Selenium	Heart and brain health
Rainbow Trout	Medium-High	Low	Protein, Vitamin D, B12	Milder alternative to salmon
Cod	Low	Low	Lean Protein, B Vitamins	Mild flavor, low-calorie meals
Canned Light Tuna	Medium	Low-Medium	Protein, B12, Selenium	Convenient, affordable protein
Shrimp	Low	Low	Protein, Astaxanthin	Low calorie, versatile

Conclusion: Building a Balanced Seafood Diet

There is no single "healthiest" fish, but rather a variety of excellent choices that offer distinct nutritional advantages. For optimal health, dietitians recommend incorporating a mix of both oily and lean fish into your diet two to three times a week, focusing on smaller, lower-mercury varieties like salmon, sardines, mackerel, and trout. Canned options are convenient and affordable ways to increase your fish intake. Choosing fish that is grilled, baked, or broiled instead of fried is also a healthier approach. By prioritizing nutrient-dense and low-mercury fish, you can effectively enhance your overall nutrition. For more information on sustainable seafood, consult organizations like the Marine Stewardship Council (MSC) or the Monterey Bay Aquarium's Seafood Watch.

Frequently Asked Questions

Both wild-caught and responsibly farmed salmon can be excellent sources of omega-3s, protein, and other nutrients. The key is prioritizing sustainable sourcing. Wild salmon is typically leaner, while some farmed salmon may have higher fat and omega-3 content depending on its feed. Look for certifications like ASC (farmed) or MSC (wild) to guide your choice.

The American Heart Association recommends eating at least two servings of fish per week, with a focus on fatty fish for the highest omega-3 intake. A serving is typically defined as 3 ounces cooked.

Yes, canned sardines are incredibly healthy. They are packed with heart-healthy omega-3s, and because their soft bones are edible, they are an excellent source of calcium and vitamin D. As small fish, they are also very low in mercury.

Pregnant and breastfeeding women should limit or avoid high-mercury fish such as king mackerel, shark, swordfish, and bigeye tuna. The FDA recommends focusing on 'Best Choices' for low mercury, including salmon, sardines, trout, and canned light tuna.

Tilapia is a lean, white fish that is low in mercury and a good source of protein. However, it is not as high in omega-3 fatty acids as oily fish like salmon or sardines. It can be part of a balanced diet when paired with other omega-3 rich foods.

Experts generally agree that eating whole fish is better than relying on supplements alone. Fish provides a complex mix of nutrients, including protein, vitamins, and minerals, that work together. Supplements can be an alternative, but fish offers the most comprehensive benefits.

To maximize the health benefits of fish, it is best to use cooking methods that don't add excessive fat or calories. Grilling, baking, broiling, and steaming are all healthy cooking options that preserve the fish's natural nutrients.