Which one is the healthiest fish to eat? A Comprehensive Guide

December 1, 2025 •

5 min read

According to the American Heart Association, eating fish at least twice a week can significantly lower the risk of heart disease. But with so many varieties available, how do you decide which one is the healthiest fish to eat? The answer depends on balancing nutrient content, particularly omega-3 fatty acids, with potential contaminants like mercury.

Quick Summary

Comparing health benefits, mercury levels, and sustainability, the healthiest fish choices generally include small, fatty fish like sardines and salmon. Factors like omega-3 content, protein, vitamins, minerals, and environmental impact are crucial for making informed decisions.

Key Points

Omega-3 Powerhouses: Oily fish like salmon, sardines, and mackerel are packed with heart and brain-boosting omega-3 fatty acids EPA and DHA.
Low Mercury is Key: Smaller fish that are lower on the food chain, such as sardines and anchovies, contain significantly less mercury than larger, predatory fish like swordfish.
Sustainability Matters: Choosing fish certified by organizations like the Marine Stewardship Council (MSC) ensures that your seafood was sourced responsibly and protects ocean ecosystems.
Wild vs. Farmed: Both wild-caught and responsibly-farmed fish can be healthy choices, but differences exist in their omega-3 content, fat levels, and mineral profiles.
Nutrient-Dense Options: In addition to omega-3s, fish provide essential protein, vitamin D, and other important minerals like selenium and B12.
Dietary Diversity: Consuming a variety of fish is recommended to balance nutrient intake and minimize exposure to any single type of contaminant.
High-Mercury Fish: Pregnant or breastfeeding women and young children should avoid high-mercury fish such as swordfish, king mackerel, and Bigeye tuna.

Finding the Healthiest Fish: Key Considerations

Choosing the healthiest fish to eat involves more than just a single species; it's about understanding the factors that influence a fish's nutritional profile and safety. The primary considerations are omega-3 fatty acid content, potential mercury contamination, and sustainability practices.

Oily Fish: The Omega-3 Powerhouses

Oily, or fatty, fish are your best source of the long-chain omega-3 fatty acids EPA and DHA, which are crucial for heart and brain health. Since the human body cannot produce these essential fats efficiently, we must get them from our diet. High intake of these omega-3s is linked to lower blood pressure, reduced inflammation, and decreased risk of cardiovascular events.

Popular fatty fish choices include:

Salmon: A versatile and popular choice, salmon is rich in both omega-3s and high-quality protein. Both wild-caught and farmed varieties are good sources, though wild salmon may have slightly more minerals.
Sardines: These small, budget-friendly fish are packed with omega-3s, and because you can eat the bones, they are an excellent source of calcium and vitamin D. Being low on the food chain, they also have very low mercury levels.
Mackerel: Atlantic mackerel is a top choice, providing abundant omega-3s, protein, and selenium. It's important to choose Atlantic mackerel over King mackerel, which has higher mercury levels.
Herring: Another small, oily fish, herring is an excellent source of omega-3s, vitamin D, and B12, and is generally low in contaminants.

White Fish: Leaner and Milder Options

White fish like cod and haddock are lower in omega-3s than oily fish but still offer excellent benefits. They are very lean, high in protein, and rich in B vitamins. For those who prefer a milder flavor or are watching their fat intake, white fish are a fantastic, healthy option. Examples include:

Cod: A great source of protein and B vitamins, cod is very low in fat and has a mild flavor.
Haddock: Similar to cod, haddock is a mild white fish that is low in fat and high in protein and nutrients.
Pollock: Often used in products like fish sticks, pollock is a lean protein source that is low in mercury.

The Mercury Dilemma: Understanding the Risks

Mercury is a neurotoxin that can accumulate in fish, particularly larger, predatory species that live longer and are higher up the food chain. For most adults, the benefits of eating fish typically outweigh the risks of mercury exposure. However, pregnant and breastfeeding women, and young children should be more cautious and limit or avoid high-mercury fish. The FDA and EPA provide guidance on which fish are 'Best Choices' and 'Choices to Avoid' based on mercury levels.

High-Mercury Fish to Avoid or Limit:

Swordfish
Shark
King Mackerel
Marlin
Bigeye Tuna
Tilefish from the Gulf of Mexico

Sustainable Choices for a Healthier Planet

For a truly healthy choice, it is essential to consider the environmental impact. Overfishing and poor aquaculture practices can damage marine ecosystems. Choosing fish from sustainable sources helps preserve fish populations and protect ocean health. Look for eco-labels from organizations like the Marine Stewardship Council (MSC) or use guides from the Monterey Bay Aquarium Seafood Watch.

Comparison of Popular Fish: Nutrition and Safety


Feature	Salmon (Wild)	Sardines (Canned)	Cod	Bigeye Tuna	Atlantic Mackerel
Omega-3s (per 3oz serving)	Very High (1.57g DHA+EPA)	Very High (1.19g DHA+EPA)	Low (0.14g DHA+EPA)	Moderate (0.7g DHA+EPA)	Very High (1.02g DHA+EPA)
Mercury Level	Low	Very Low	Low	High	Low
Protein (per 3oz serving)	High (22g)	High (22g)	High (23g)	High (25g)	High (21g)
Sustainability	Variable; check source	Generally Sustainable	Variable; check source	Avoid or limit	Generally Sustainable
Calcium	Moderate	Very High (from bones)	Low	Low	Moderate

Making the Best Choice for You

The ultimate choice for the healthiest fish is a personal one, depending on your health goals, taste preferences, budget, and environmental concerns. For a combination of high omega-3s and low mercury, small, oily fish like sardines, anchovies, and Atlantic mackerel are often top contenders. Salmon and trout are also excellent and widely available options. If you prefer a milder flavor, leaner white fish like cod and haddock offer great protein and other nutrients with very low mercury levels.

Practical Tips for a Healthier Seafood Diet

Vary your intake: Don't rely on just one type of fish. By consuming a wide variety, you diversify your nutrient intake and minimize potential exposure to contaminants.
Look for sustainable labels: Support responsible fishing and aquaculture by choosing products with certifications like the MSC blue tick.
Consider canned fish: Canned salmon and sardines offer a convenient and affordable way to boost your omega-3 intake. Canned sardines are particularly beneficial for their added calcium from the soft, edible bones.
Prioritize cooking method: Bake, grill, or steam your fish instead of frying to keep the fat content low and preserve nutrients.
Follow specific guidelines: If you are pregnant, nursing, or feeding young children, pay close attention to the FDA's advice regarding mercury levels.

Conclusion: A Balanced Approach to Seafood

There is no single "healthiest" fish for everyone, but by considering omega-3 content, mercury levels, and sustainability, you can make an informed decision that benefits both your health and the environment. Incorporating a variety of low-mercury, high omega-3 fish like salmon, sardines, and trout into your diet twice a week is a powerful way to support heart and brain health. For the best environmental and health outcomes, seek out certified sustainable options and explore the diversity of seafood available. To learn more about environmental impacts and specific species recommendations, you can consult resources like the Seafood Watch guide.

A Note on Dietary Needs and Concerns

While this article provides general guidance, individuals with specific health conditions or allergies should consult a healthcare provider or a registered dietitian. Pregnant women, for example, have specific dietary recommendations to follow regarding seafood consumption to ensure a balance between vital omega-3s for fetal development and avoiding high mercury levels. For those who do not eat fish, plant-based sources like walnuts, flaxseed, and algae oil can provide essential omega-3s.

Frequently Asked Questions

Oily, or fatty, fish generally have the highest concentration of omega-3 fatty acids. Top choices include Atlantic mackerel, sardines, herring, salmon, and trout.

Pregnant and breastfeeding women should avoid high-mercury fish such as shark, swordfish, king mackerel, and Bigeye tuna. They should instead focus on low-mercury options like salmon, sardines, and trout, and limit overall intake to 8-12 ounces per week.

Both can be healthy, but there are differences. Wild-caught fish tend to be leaner with a slightly different mineral profile, while farmed fish can have higher omega-3 levels due to their diet. For many species, responsibly farmed fish is a great, sustainable option.

No, cooking methods like frying, grilling, or baking do not reduce the amount of mercury in fish. Mercury is tightly bound to the muscle tissue and is not affected by heat.

For lower mercury levels, light canned tuna (often skipjack) is a better choice for more frequent consumption than canned albacore or fresh/frozen Bigeye tuna. Tuna still contains good nutrients, but moderation is key due to mercury concerns.

Yes, small fish like anchovies and sardines are among the safest and healthiest choices. They are low in mercury because they are low on the food chain and provide excellent omega-3s, protein, and calcium.

Look for certifications from organizations like the Marine Stewardship Council (MSC) on packaging. You can also use online guides from the Monterey Bay Aquarium Seafood Watch, which rates seafood based on sustainability.