Which fish are considered the healthiest? An in-depth guide

December 1, 2025 •

4 min read

According to the American Heart Association, consuming fish at least two times per week can reduce the risk of cardiovascular disease. This dietary pattern, featuring fatty fish especially, is a cornerstone of heart-healthy eating plans. So, which fish are considered the healthiest to integrate into your diet?

Quick Summary

This guide details the top seafood choices for optimal health, focusing on high omega-3 fatty acids and low mercury content. It covers the benefits of oily fish, compares wild-caught versus farmed options, and provides a list of fish to limit or avoid.

Key Points

Fatty fish are richest in omega-3s: Oily fish like salmon, sardines, and mackerel are the best dietary source of anti-inflammatory EPA and DHA.
Small fish often mean low mercury: Smaller fish like sardines and anchovies are typically lower on the food chain, resulting in very low mercury levels.
Variety is key for balanced nutrition: Incorporating a mix of oily fish for omega-3s and lean white fish for protein and vitamins is ideal for a comprehensive diet.
Sustainability is a factor in health: Choosing fish from sustainable sources, like those certified by the MSC or ASC, supports healthy ecosystems for future generations.
Limit high-mercury species: Predatory fish such as swordfish, shark, and king mackerel should be consumed in moderation due to higher mercury levels.
Wild vs. farmed is not a simple choice: Both wild-caught and responsibly farmed fish can be healthy options, with specific sustainability concerns varying by species and farming method.

The Case for Fatty Fish: Omega-3 Powerhouses

When evaluating which fish are considered the healthiest, the conversation almost always starts with fatty or oily fish. These species are packed with beneficial omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Unlike other fats, the body cannot produce these on its own, making dietary intake essential. Omega-3s are renowned for their anti-inflammatory properties and their role in promoting brain and heart health.

Top Contenders for Healthy Fats

Several fish species consistently top nutritionists' lists for their omega-3 content and overall health profile. Here are some of the best:

Salmon: A versatile and popular choice, salmon is an excellent source of omega-3s, high-quality protein, and vitamin D. Both wild and responsibly farmed varieties offer significant health benefits.
Sardines: These small, inexpensive fish are incredibly nutrient-dense. A single can of sardines can provide more omega-3s than salmon and is a great source of calcium and vitamin D because the bones are edible.
Mackerel: Rich in omega-3s, protein, and selenium, Atlantic mackerel is a strong contender for a healthy diet. It is often a more sustainable choice compared to other larger fish.
Trout: As a close relative to salmon, trout offers a similar nutrient profile with a milder taste, making it a great alternative. Freshwater rainbow trout is a particularly sustainable option.
Herring: An oily fish known for being high in omega-3s, herring is a great choice that can often be found canned or pickled, providing a long shelf life.

Low-Mercury White Fish for Everyday Meals

While fatty fish get a lot of attention, milder white fish also provide valuable nutrition without high levels of mercury, making them excellent staples for frequent consumption. They are typically lower in calories and fat but still provide a significant amount of lean protein and essential nutrients like B vitamins.

The Best White Fish Options

Cod: A classic, mild-tasting fish that is high in protein and an excellent source of vitamin B12, supporting energy production and nervous system health.
Haddock: Similar to cod, haddock is another lean, high-protein white fish. It is versatile for cooking and widely available.
Flounder/Sole: These delicate, flaky fish are very low in calories and fat while providing a good dose of protein. They are also considered low in mercury.
Shrimp: The most popular seafood in America, shrimp is a low-calorie, high-protein crustacean rich in astaxanthin, a powerful antioxidant.

Important Factors for Choosing the Healthiest Fish

Making a healthy seafood choice goes beyond just looking at the omega-3 content. Consumers should also consider the potential for contaminants like mercury and the overall environmental impact. Several resources, such as the Monterey Bay Aquarium's Seafood Watch and the NOAA Fisheries website, provide up-to-date guidance on sustainable and safe seafood options.

Wild-Caught vs. Farmed Fish

The debate over wild-caught versus farmed fish is nuanced. While wild-caught fish often have leaner meat and a potentially lower exposure to certain contaminants, some farmed fish, particularly those raised in closed-loop recirculating aquaculture systems (RAS), can be highly sustainable and nutritious. For example, farmed rainbow trout is often a great choice. Some farmed salmon, however, has been criticized for potential environmental impacts. Looking for certifications like the Marine Stewardship Council (MSC) or the Aquaculture Stewardship Council (ASC) can help guide your decision.

Mercury Levels: A Critical Consideration

Larger, longer-living predatory fish tend to accumulate higher levels of mercury. This is a special concern for pregnant and breastfeeding women, as well as young children, who should limit their intake of certain fish. The FDA categorizes fish based on their mercury levels, making it easier for consumers to make informed choices. For most people, consuming a variety of low-mercury fish is the safest approach.

Comparison Table: Healthy Fish at a Glance


Fish Type	Omega-3 Content	Protein	Mercury Level	Notes
Salmon (wild)	High	High	Low	Excellent source of DHA/EPA; often higher than farmed.
Sardines (canned)	Very High	High	Very Low	Exceptionally high in omega-3s, calcium, and vitamin D.
Atlantic Mackerel	High	High	Low	Offers high omega-3s and selenium; good sustainability.
Rainbow Trout (farmed)	Medium	High	Low	Mild flavor; often farmed sustainably in freshwater.
Cod	Low	High	Very Low	Lean, mild white fish high in vitamin B12.
Shrimp	Low	High	Very Low	Popular, low-cal protein source with antioxidant astaxanthin.
Albacore Tuna (canned, light)	Medium	High	Medium	Higher mercury than light tuna; limit consumption.
Swordfish	High	High	Very High	Very high in mercury; consumption should be limited.

Conclusion

The question of which fish are considered the healthiest has a clear answer: prioritize variety and knowledge. Oily fish like salmon, sardines, and mackerel are packed with essential omega-3s, while lean white fish such as cod and flounder provide high-quality protein with low mercury levels. By consulting resources like the FDA and Seafood Watch, and understanding the wild vs. farmed and mercury trade-offs, you can confidently add fish to your diet for a wide range of health benefits.

How to Incorporate Healthy Fish into Your Diet

Integrating more fish into your meals can be simple and delicious. Here are a few ideas:

Grill or bake salmon with lemon and herbs for a nutrient-dense main course.
Mash canned sardines or light tuna into a spread for avocado toast.
Add chopped shrimp to pasta or salads for a quick protein boost.
Use mild white fish, like cod or haddock, in soups, stews, or tacos.
Create a Mediterranean-inspired bowl with canned tuna, olives, tomatoes, and balsamic vinegar over whole grains.

By being mindful of your choices, you can reap the significant health rewards that seafood has to offer. For more information on sustainable seafood practices and specific guidelines for consumption, the NOAA Fisheries website is an excellent resource.

Frequently Asked Questions

Wild-caught salmon can contain higher levels of omega-3s and may have fewer contaminants like antibiotics. However, responsibly farmed salmon, especially from closed-loop systems, is a highly sustainable and healthy alternative with comparable nutrient levels and low contaminant risk.

The highest concentrations of omega-3s are found in fatty fish like sardines, salmon, mackerel, trout, and herring. Ounce for ounce, canned sardines often contain more omega-3s than salmon.

Fish with low mercury levels include smaller, shorter-lived species like salmon, sardines, trout, anchovies, cod, and shrimp. These are considered 'best choices' for frequent consumption by health organizations.

The American Heart Association recommends eating at least two servings of non-fried fish, particularly fatty fish, per week. A serving is defined as 3.5 ounces cooked.

Yes, pregnant women, women who may become pregnant, and young children should avoid high-mercury fish such as shark, swordfish, king mackerel, and big-eye tuna. They should focus on low-mercury options to gain the benefits of DHA for brain development.

Yes, canned fish like sardines and light tuna are excellent, budget-friendly sources of protein and omega-3s. Canned sardines, in particular, are an outstanding source of calcium because the bones are softened and can be consumed.

To ensure your seafood is sustainable, look for eco-labels such as the Marine Stewardship Council (MSC) or Aquaculture Stewardship Council (ASC). Resources like the Monterey Bay Aquarium's Seafood Watch also provide guides for making environmentally responsible choices.