Which fish is the healthiest to eat in the world? A guide to making the best choices

October 19, 2025 •

3 min read

According to the Food and Agricultural Organization, only 65% of the world's fish stocks were operating at biologically sustainable levels in 2019, highlighting the importance of making conscious choices. When it comes to determining which fish is the healthiest to eat in the world, the answer involves a balance of nutritional content, mercury levels, and environmental sustainability. Factors like omega-3 fatty acids, vitamins, minerals, and potential contaminants must all be considered to make the most informed decision for your health and the planet.

Quick Summary

This guide examines the factors determining the healthiest fish, including essential omega-3s, low mercury levels, and sustainable sourcing. Discover top choices like sardines, salmon, and mackerel, and learn which species to limit for a nutritious and responsible diet. Practical advice helps you incorporate these options into your meals.

Key Points

Small, Oily Fish are Top Tier: Sardines, Atlantic mackerel, and herring offer the highest concentration of omega-3 fatty acids with the lowest mercury risk due to their size and short lifespan.
Salmon is a Nutritious Favorite: Both wild-caught and responsibly farmed salmon are excellent sources of omega-3s, protein, and vitamins, and are considered a low-mercury option.
Low-Mercury White Fish Options: For a leaner protein source with very low mercury, cod, pollock, and freshwater trout are all highly recommended.
Sustainability is Key: Look for certifications from the Marine Stewardship Council (MSC) to ensure your fish is sourced from well-managed fisheries that protect marine ecosystems.
Fish to Limit or Avoid: Larger predatory fish like King mackerel, shark, and swordfish contain the highest levels of mercury and should be limited, especially for pregnant women and young children.

The Case for Oily Fish: Why Omega-3s Matter

For a fish to be considered among the healthiest, it must be rich in omega-3 fatty acids, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). The human body cannot produce these essential fats, which are crucial for heart health, brain function, and reducing inflammation.

Omega-3 Powerhouses

Small, oily fish often contain the highest concentrations of omega-3s while also being low in mercury, making them a top-tier choice.

Sardines: A standout for nutritional density, sardines are packed with omega-3s, protein, calcium, and vitamin D. Since they are low on the food chain, they accumulate very little mercury. Canned sardines are particularly beneficial as the edible bones provide a calcium boost.
Mackerel: Atlantic mackerel is another excellent option, rich in omega-3s, vitamin B12, and selenium. Smaller varieties of mackerel generally have lower mercury levels than the larger King mackerel.
Salmon: A versatile and popular fatty fish, salmon is a great source of omega-3s, protein, vitamin B12, and selenium. Wild-caught salmon is often praised for being leaner and having a lower risk of contaminants, while responsibly farmed salmon remains a very healthy and accessible choice.
Herring: Similar in size and benefits to sardines and mackerel, herring offers high levels of omega-3s, vitamin D, and B12.
Anchovies: These small, salty fish are low in mercury and high in omega-3s, protein, and calcium, making them a nutritious addition to many dishes.

The Mercury Factor: Small Fish are a Safer Bet

Mercury is a heavy metal that can accumulate in fish, and consuming high levels can be harmful, especially for vulnerable populations like pregnant women and young children. As a general rule, larger, predatory fish that live longer tend to have higher mercury concentrations.

Low-Mercury Champions

Fish listed as a "Best Choice" by the FDA and EPA have the lowest mercury levels and can be enjoyed frequently.

Catfish: A mild, white fish that is low in mercury.
Cod: A lean protein source low in fat and calories, also considered a "Best Choice" for low mercury.
Pollock: A popular choice for fish sticks and fillets, pollock is low in mercury and a good source of lean protein.
Trout (Freshwater): A good alternative to salmon with a milder flavor, freshwater trout is low in mercury and a source of omega-3s and vitamin D.
Tilapia: While lower in omega-3s, tilapia is a low-mercury fish and a lean protein source.

Making a Sustainable and Healthy Choice

For the ultimate in healthy eating, it is vital to consider the source of your fish. Overfishing and unsustainable practices harm marine ecosystems. The Marine Stewardship Council (MSC) and the Monterey Bay Aquarium's Seafood Watch provide reliable information on the most sustainable options.

Comparison of Healthy Fish Varieties


Feature	Sardines	Salmon	Atlantic Mackerel	Cod	Canned Light Tuna
Omega-3s	Very High	High	High	Moderate/Low	Moderate
Mercury Level	Very Low	Low	Low	Low	Low
Protein	High	High	High	High	High
Vitamin D	Excellent Source	Good Source	Good Source	Good Source	Moderate
Calcium	Very High (with bones)	Moderate	Low	Low	Moderate (with bones)
Cost	Budget-friendly	Moderate/High	Budget-friendly	Moderate	Budget-friendly
Sustainability	Varies, check labels	Wild or Farmed, check labels	Varies, check labels	Varies, check labels	Varies, pole-and-line best

Conclusion: Choosing for Maximum Nutrition and Safety

While there is no single fish universally considered the healthiest, small, oily fish like sardines, Atlantic mackerel, herring, and salmon consistently rank highest due to their exceptional omega-3 content and low mercury levels. Sardines and Atlantic mackerel, in particular, offer an incredible nutritional punch while remaining low in contaminants and generally budget-friendly. Lean white fish like cod and pollock are also excellent low-mercury, high-protein choices for those who prefer a less oily taste. When choosing, always prioritize sustainability by looking for eco-certifications like the MSC label. By focusing on these fatty, low-mercury, and sustainably sourced options, you can ensure a nutritious and responsible diet that benefits both your body and the planet's oceans.

Frequently Asked Questions

Both farmed and wild-caught fish can be healthy options. While wild-caught salmon may be leaner, farmed fish can sometimes contain higher omega-3 levels due to their controlled diet. The key is to choose responsibly sourced products, regardless of whether they are farmed or wild.

The fish with the highest omega-3 levels include small, oily species like sardines, mackerel, and herring, as well as salmon. Some types of tuna, such as slender tuna, also show very high omega-3 levels, though species like bigeye tuna should be limited due to higher mercury.

Fish with the lowest mercury levels are generally smaller species that are lower on the food chain. Options like anchovies, sardines, salmon, Atlantic mackerel, cod, and pollock are considered "Best Choices" by the FDA and EPA.

No, pregnant women should not avoid fish completely. Health organizations recommend eating 2-3 servings per week of low-mercury fish to benefit from the omega-3s crucial for fetal brain development. However, they should avoid high-mercury fish like shark and swordfish.

Eating fish regularly has numerous health benefits, including supporting heart and brain health, reducing inflammation, lowering blood pressure, and providing essential nutrients like vitamins D and B12, selenium, and high-quality protein.

To ensure your fish is sustainably sourced, look for certifications from organizations like the Marine Stewardship Council (MSC) on the packaging. You can also consult guides like the Monterey Bay Aquarium's Seafood Watch, which provide information on which fish are environmentally friendly.

Smaller, lower-trophic fish like sardines, anchovies, and Atlantic mackerel are often more environmentally friendly. Aquaculture, when managed responsibly, also offers sustainable options. Consumers can check eco-labels and consult seafood guides for the best choices.