Uncovering: What is the healthiest fatty fish?

October 3, 2025 •

4 min read

The American Heart Association recommends eating two servings of fatty fish per week for better cardiovascular health. But with so many options available, a common question arises: What is the healthiest fatty fish? The answer lies in balancing high omega-3 content with low mercury levels and other key nutrients.

Quick Summary

Several small, oily fish are top contenders for the healthiest fatty fish due to high omega-3s and low mercury. Comparing factors like protein, vitamins, and minerals helps determine the best choice for your dietary needs.

Key Points

Sardines are a top choice: Extremely low in mercury and packed with omega-3s, sardines also offer high calcium when eaten canned with bones.
Mackerel is an omega-3 powerhouse: Atlantic and Pacific chub mackerel are excellent, sustainable sources of omega-3 fatty acids and selenium, with lower mercury than larger species.
Salmon is a heart-healthy classic: Renowned for its omega-3 content, salmon is a great option. Wild-caught is often higher in omega-3s and lower in contaminants, though farmed can also be nutritious.
Mercury levels matter: Smaller fish lower on the food chain, like sardines and herring, have much lower mercury levels than large predators like shark and swordfish.
The benefits of canned fish: Canned sardines and salmon offer a convenient, affordable way to get omega-3s. Canned varieties often retain most nutrients and can even provide calcium.
Variety is key: Rotating your fatty fish choices provides a wider spectrum of nutrients and helps to mitigate any risks from contaminants.
Prioritize healthy cooking methods: Baking, grilling, and broiling are the best ways to prepare fatty fish, avoiding the extra fat and calories associated with frying.

The Nutritional Power of Fatty Fish

Fatty fish, also known as oily fish, are a cornerstone of a heart-healthy diet, primarily due to their high concentration of long-chain omega-3 fatty acids, specifically EPA and DHA. The human body cannot produce these essential fats on its own, making dietary intake crucial. These fatty acids play a vital role in reducing inflammation, supporting brain function, and lowering the risk of heart disease and stroke by improving blood vessel elasticity, reducing blood clots, and lowering blood pressure and triglycerides.

Beyond omega-3s, fatty fish are also packed with high-quality protein, essential for muscle repair and growth. Many varieties also provide significant amounts of vitamin D, which is vital for immune function and bone health, and vitamin B12, important for nerve function and energy production. The challenge for consumers is navigating the options to find the best balance of nutritional benefits, affordability, and minimal contaminants, particularly mercury.

Top Contenders for Healthiest Fatty Fish

Sardines: Small Fish, Big Benefits

These tiny, silvery fish are often considered one of the healthiest fatty fish options due to their exceptionally low mercury content and impressive nutritional profile. Because they are small and low on the food chain, they accumulate very little mercury. Canned sardines, in particular, are a nutritional powerhouse, as they are often consumed with their soft, edible bones, providing a substantial dose of calcium.

Mackerel: Rich in Omega-3s and Selenium

Mackerel is another excellent source of omega-3s, protein, and selenium, which supports a healthy immune system. When choosing mackerel, it is important to differentiate between types, as Atlantic or Pacific chub mackerel are lower in mercury than the larger king mackerel. It is often available fresh, canned, or smoked, with the canned or fresh varieties being the healthiest options to avoid the high sodium and potential nitrates of smoked versions.

Salmon: The Popular Powerhouse

Salmon is arguably the most well-known fatty fish, celebrated for its delicious flavor and high omega-3 content. Both wild-caught and farmed salmon offer significant nutritional benefits. However, wild-caught salmon generally contains higher omega-3 levels and fewer contaminants, while farmed salmon can be a more affordable and consistent option, often fed diets that boost their omega-3 content. Wild-caught sockeye and pink salmon are particularly recommended for their sustainability and low mercury levels.

Other Healthy Fatty Fish Options

Herring: This small, oily fish is high in omega-3s and offers similar benefits to sardines and mackerel. Like other smaller fish, it is low in mercury.
Trout: Particularly lake trout, can be an excellent source of omega-3s and vitamin D. Freshwater farmed trout can also be a sustainable and healthy choice.
Anchovies: These small, salty fish are packed with omega-3s, calcium, and protein. Due to their high sodium content from curing, they should be consumed in moderation, but a little goes a long way in adding flavor.
Canned Light Tuna: Made from smaller skipjack tuna, canned light tuna is a lower-mercury alternative to albacore or bigeye tuna. While not as rich in omega-3s as salmon or sardines, it still contributes to a healthy diet.

Comparing the Healthiest Fatty Fish


Feature	Salmon	Sardines	Mackerel	Canned Light Tuna
Omega-3s (EPA/DHA)	High	Very High	Very High	Modest
Mercury Content	Very Low	Very Low	Low (Atlantic/Chub)	Moderate (Lower than Albacore)
Calcium	Low (unless canned with bones)	High (due to edible bones)	Low	Low
Vitamin D	High	High	High	Contains some
Protein	High	High	High	Very High
Affordability	Moderate	Very Affordable	Affordable	Very Affordable

Mercury Levels and Sustainability

When choosing fatty fish, it is essential to consider the potential for mercury contamination, especially for vulnerable populations like pregnant women and young children. Mercury is a neurotoxin that bioaccumulates up the food chain, meaning larger, longer-lived predatory fish tend to have the highest concentrations. Fish to avoid or limit due to high mercury levels include king mackerel, shark, swordfish, and bigeye tuna. For most healthy adults, the benefits of eating low-mercury fatty fish far outweigh the risks of trace mercury exposure.

Sustainability is another important factor. The Monterey Bay Aquarium's Seafood Watch provides excellent guidance on making eco-friendly choices. Many canned fish, like sardines and pink salmon, are often sustainably sourced.

Conclusion: Making the Best Choice for You

Ultimately, there is no single "healthiest" fatty fish, but several excellent contenders. Sardines, mackerel (Atlantic/chub), and salmon consistently rank at the top due to their superior omega-3 content and low mercury levels. For the best of all worlds—high omega-3s, low mercury, and a calcium boost—canned sardines are an exceptional choice. The best strategy is to incorporate a variety of low-mercury fatty fish into your diet, aiming for two servings per week as recommended by the American Heart Association. Whether fresh or canned, baked, grilled, or broiled, these nutritional powerhouses can significantly contribute to your overall well-being. For more detailed information on heart health, refer to the guidance provided by the American Heart Association(https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/fish-and-omega-3-fatty-acids).

Tips for enjoying your fatty fish:

Prioritize variety: Rotate between different low-mercury fatty fish to get a broader range of nutrients and minimize exposure to any single contaminant.
Cook healthily: Opt for baking, grilling, or broiling instead of deep-frying to maximize health benefits and avoid adding unhealthy fats.
Choose canned wisely: Look for fish canned in water or extra virgin olive oil. For sardines and salmon, consider options with edible bones for added calcium.
Flavor with herbs: Season your fish with fresh herbs, lemon, or spices to enhance flavor without adding excessive sodium.

Frequently Asked Questions

Sardines and mackerel generally have very high omega-3 fatty acid content, often surpassing that of salmon on a per-serving basis. Sockeye salmon is another excellent source, especially wild-caught varieties.

Yes, canned sardines are very healthy. They are rich in omega-3s, protein, and contain high levels of calcium because their soft bones are typically consumed. They are also known for being very low in mercury.

Wild-caught fish, such as wild salmon, generally contains higher amounts of omega-3 fatty acids and fewer contaminants. However, farmed fish can also be a healthy option, with consistent levels of nutrients, and often comes at a lower price point.

Larger, predatory fatty fish like king mackerel, shark, swordfish, and bigeye tuna should be avoided or limited due to their high mercury levels. Smaller fish, like sardines and Atlantic mackerel, are much lower in mercury.

To maximize health benefits, it's best to cook fatty fish by baking, grilling, or broiling. These methods help retain the fish's nutritional value, particularly its delicate omega-3 fats, compared to frying.

Yes, pregnant women can and should eat fatty fish that are low in mercury, such as sardines and salmon. Regulatory bodies like the FDA recommend two to three servings per week of low-mercury fish for pregnant or nursing women.

Canned light tuna (made from skipjack) is a good source of protein and provides some omega-3s. However, it is lower in omega-3s than fish like salmon or sardines. Opt for light canned tuna and eat it in moderation due to its moderate mercury levels.