What is the healthiest oily fish to eat? A comprehensive nutritional guide

October 26, 2025 •

3 min read

The American Heart Association recommends eating fish rich in omega-3s at least twice a week to support heart health. With many delicious and beneficial options available, the important question is: what is the healthiest oily fish to eat?

Quick Summary

Analyzes the top contenders for the healthiest oily fish, evaluating them based on their omega-3 content, mercury levels, and sustainability. The guide provides practical information to help you choose the most nutritious option for your diet.

Key Points

Sardines and Anchovies are Top Tier: These small, low-mercury fish offer high levels of omega-3 fatty acids and provide a great source of calcium when eaten canned with bones.
Wild vs. Farmed is a Trade-Off: Wild-caught fish can be leaner with a better nutrient profile, but farmed options are widely available and can still be very healthy, especially when sourced responsibly.
Smaller Fish Mean Lower Mercury: As a general rule, smaller oily fish that are lower on the food chain, such as sardines and Atlantic mackerel, have significantly lower mercury levels than larger predators like swordfish.
Variety is the Healthiest Strategy: Consuming a variety of low-mercury oily fish helps diversify your nutrient intake while minimizing risk from potential contaminants.
Sustainability Matters: Choosing fish with Marine Stewardship Council (MSC) certification helps protect ocean ecosystems for future generations.
Preparation is Key: To maximize health benefits, opt for grilling, baking, or steaming your fish rather than frying it.

Why Choose Oily Fish?

Oily fish, also known as fatty fish, are rich sources of long-chain omega-3 fatty acids (EPA and DHA), which are vital for heart health and brain function. These healthy fats are crucial because the human body cannot produce them efficiently on its own. Regular consumption of oily fish has been associated with numerous health benefits, including a reduced risk of cardiovascular disease, improved brain development in children, and better cognitive function in adults. They also provide high-quality protein, vitamin D, B vitamins, and essential minerals like selenium.

The Top Contenders for Healthiest Oily Fish

Several oily fish stand out for their nutritional profiles and lower mercury levels, making them excellent choices for a healthy diet.

Sardines

Small and silver, sardines are exceptionally nutritious and low in mercury. They are rich in omega-3s and, when canned and consumed whole, provide a good source of calcium and phosphorus. A 3-ounce serving often provides over 1.5 grams of omega-3s. Their small size and position in the food chain result in very low mercury levels. Sardines are also frequently a sustainable choice, especially from MSC-certified fisheries.

Salmon

Salmon is a popular oily fish known for its high protein and omega-3 content. Whether wild-caught or farmed, salmon is a nutritious option, though there are differences to consider. Wild-caught salmon is often leaner with a favorable omega-3 profile, while farmed salmon can be higher in total fat and may have varying omega-3 and omega-6 ratios depending on feed. Both wild and farmed salmon typically have low mercury levels. Sustainability of wild salmon varies, with Alaskan salmon often considered a responsible choice, while farmed salmon's sustainability depends on regulations and practices.

Atlantic Mackerel

Atlantic mackerel is a small, fast-growing oily fish that provides an excellent source of omega-3s, protein, and selenium. It has high omega-3 levels and a favorable omega-3 to omega-6 ratio. Mercury levels in Atlantic mackerel are lower compared to larger mackerel species. North-east Atlantic mackerel is often a good option, but sourcing should be checked for sustainability.

Herring and Anchovies

Both herring and anchovies are small forage fish that are exceptionally healthy due to their high omega-3 content and very low mercury levels. Herring is an affordable option rich in omega-3s and vitamin D. Anchovies, often sold canned or jarred, are a flavorful way to boost omega-3 intake.

Rainbow Trout

Often farmed in freshwater ponds, rainbow trout is a good source of omega-3s, vitamin B12, and vitamin D. It has low mercury levels, making it a safe option. Freshwater farmed rainbow trout is frequently considered a sustainable choice.

Comparison of Healthiest Oily Fish Options


Feature	Sardines	Salmon (Wild vs. Farmed)	Atlantic Mackerel	Herring	Rainbow Trout
Omega-3s	Very high (EPA & DHA)	High (Varies, wild often better ratio)	High (EPA & DHA)	High (EPA & DHA)	High (EPA & DHA)
Mercury Risk	Very Low	Very Low	Low	Very Low	Low
Sustainability	Often High	Varies (Wild Alaskan often sustainable)	Often High	Generally High	Often High (freshwater farmed)
Key Nutrients	Calcium, Vitamin B12	Vitamin D, Selenium, Protein	Selenium, Protein, Vitamin B12	Vitamin D, Protein	Vitamin D, Vitamin B12
Convenience	Canned, Fresh	Fresh, Canned, Frozen	Fresh, Canned, Smoked	Fresh, Smoked	Fresh, Frozen

Factors to Consider When Choosing

Beyond omega-3 content and mercury levels, consider these additional factors to make the most informed decision for your health and the environment:

Wild-Caught vs. Farmed: Both wild-caught and farmed fish can be healthy. Wild fish may have slightly higher omega-3s and fewer contaminants, while farmed fish are often more accessible and affordable. Choose responsibly sourced options regardless of type.
Sustainability: Look for certifications like the Marine Stewardship Council (MSC) to support sustainable fishing practices.
Preparation: Healthy preparation methods like baking, grilling, or steaming are preferable to deep-frying.

Conclusion: Making the Best Choice for You

Determining what is the healthiest oily fish to eat? isn't a one-size-fits-all answer. Smaller fish like sardines, anchovies, and herring are excellent for high omega-3s, low mercury, and affordability. Salmon, both wild and responsibly farmed, remains a top source of omega-3s. Atlantic mackerel and freshwater trout also offer great nutritional value with low mercury concerns. Including a variety of these fish in your diet is the best approach for diverse nutrient intake and minimizing contaminant exposure.

For more detailed guidance on safe seafood consumption, especially concerning mercury levels, consult reputable sources like the U.S. Environmental Protection Agency (EPA) or the Food and Drug Administration (FDA) advice on eating fish.

Frequently Asked Questions

Yes, canned oily fish like sardines and salmon are excellent sources of omega-3s. In some cases, such as with canned sardines, eating the softened bones provides an added benefit of calcium.

Larger, predatory fish tend to accumulate higher levels of mercury. The FDA recommends limiting or avoiding large species like king mackerel, swordfish, shark, and bigeye tuna, especially for pregnant women and young children.

Yes, their diet and environment cause some nutritional differences. Wild salmon generally has a better omega-3 to omega-6 ratio, while farmed salmon can have higher total fat. Both are healthy, but wild is often preferred for its slightly superior nutritional composition and flavor.

The American Heart Association recommends eating two servings of fish, particularly fatty fish, per week. A serving is about 3 ounces cooked.

Omega-3s from oily fish provide numerous benefits, including reducing the risk of heart disease, lowering blood pressure, supporting brain development, and improving overall cognitive function.

Canned light tuna does not count as an oily fish because it has much lower omega-3 levels, although canned albacore tuna has higher levels. Shrimp contain omega-3s, but not as much as oily fish. The richest omega-3 sources are salmon, sardines, mackerel, and herring.

Look for third-party certifications, such as the Marine Stewardship Council (MSC) label, which indicates that the fish has been caught in a sustainable and environmentally responsible manner.