Which seafood is the healthiest?

October 25, 2025 •

4 min read

According to the American Heart Association, consuming at least two servings of fatty fish per week can significantly improve heart health. So, with a wide variety of options available, which seafood is the healthiest to incorporate into your diet for maximum nutritional benefits and safety?

Quick Summary

This guide examines the most nutritious seafood choices, highlighting those rich in omega-3s, low in mercury, and sustainably sourced for optimal dietary health.

Key Points

Fatty Fish are Omega-3 Stars: Small, fatty fish like sardines, mackerel, and salmon are excellent sources of heart and brain-healthy omega-3s, and are generally low in mercury.
Shellfish Offers Unique Nutrients: Oysters provide exceptional levels of zinc and vitamin B12, while mussels are a sustainable source of protein and manganese.
Choose Smaller Fish for Lower Mercury: Predatory fish like shark and king mackerel accumulate more mercury. Opting for smaller fish like sardines and anchovies minimizes this risk.
Wild vs. Farmed Choices Vary: Wild-caught fish like Alaskan salmon often have fewer contaminants, but some responsibly farmed seafood, particularly shellfish, is also an excellent option.
Prioritize Sustainability: Using resources like the Seafood Watch guide helps ensure your seafood choices are both healthy for you and better for the environment.
Cooking Method Matters: Health benefits are maximized by baking, grilling, or steaming fish, rather than deep-frying.

For anyone looking to enhance their diet, seafood offers a powerful array of nutrients. However, navigating the best options requires consideration of several factors, including omega-3 content, mercury levels, and sustainability. By prioritizing species that offer high nutritional value with low environmental impact and minimal contaminants, you can make smarter, healthier choices.

The Top Contenders for Healthiest Seafood

Omega-3 Powerhouses: Fatty Fish

Fatty fish are nutritional superstars, providing high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two crucial omega-3 fatty acids that support heart health, brain function, and reduce inflammation. Many of the best choices also happen to be small, low-mercury fish.

Salmon: A versatile and popular choice, salmon is rich in omega-3s, vitamin D, and protein. Opt for wild-caught Alaskan salmon whenever possible, as it is often leaner and has lower contaminant levels than farmed varieties.
Sardines: These small, oily fish are packed with omega-3s and are one of the best whole-food sources of calcium and vitamin D, thanks to their edible bones. Sardines are also very low in mercury due to their small size and position on the food chain.
Mackerel: Atlantic and Pacific chub mackerel are excellent sources of omega-3s and are generally low in mercury. As a bonus, mackerel provides a healthy dose of vitamin B12 and selenium. King mackerel, however, should be avoided due to high mercury levels.
Herring: Similar to sardines and mackerel, herring is a fatty fish that is low in mercury and high in omega-3s, vitamin D, and vitamin B12. Pickled herring is a staple in many healthy Nordic diets.
Anchovies: Tiny but mighty, anchovies are a great source of omega-3s, protein, and calcium, and have extremely low mercury levels.

Shellfish: Nutrient-Dense and Sustainable

Many types of shellfish are low in calories and saturated fat while providing essential minerals like zinc, iron, and selenium. Bivalves, in particular, are often highly sustainable choices.

Oysters: These mollusks are a true nutritional powerhouse, containing more zinc than any other food. They also offer significant amounts of vitamin B12, selenium, and iron, and are one of the most sustainable seafood options.
Mussels: Inexpensive and eco-friendly, mussels are rich in omega-3 fatty acids, vitamin B12, and manganese. They are filter feeders that actually clean the water they live in, making them a great environmental choice.
Clams: Like other bivalves, clams are packed with essential nutrients, including iron and vitamin B12, and are low in mercury.

Lean and Clean: Low-Mercury White Fish

White fish offer a great source of lean protein and important minerals, and are generally a safe choice regarding mercury levels, provided they are not large predatory species.

Cod: A British classic, cod is a lean, mild-flavored white fish that is high in protein and a good source of vitamin B12. It is also relatively low in mercury compared to other larger fish.
Haddock: Similar to cod, haddock is a good source of lean protein and minerals. Both are a mild-tasting option for those who dislike a stronger fish flavor.

Seafood Comparison Table


Seafood	Key Nutrients	Omega-3s	Mercury Level	Sustainability
Wild Alaskan Salmon	Protein, Vitamin D, B vitamins	High	Low	Excellent (wild-caught)
Sardines	Protein, Calcium, Vitamin D, B12	High	Very Low	Excellent
Atlantic Mackerel	Protein, B12, Selenium	High	Low	Good
Oysters	Zinc, B12, Iron, Protein	Moderate	Very Low	Excellent (farmed)
Mussels	Protein, B12, Manganese	Moderate	Very Low	Excellent (farmed)
Cod	Protein, B12, Selenium	Low	Low	Good, depending on source
Canned Light Tuna	Protein, B12, Selenium	Low	Low	Variable (check label)

Making Sustainable and Ethical Choices

When selecting seafood, sustainability is a critical factor. Overfishing, habitat damage, and the use of antibiotics in some farmed fish can harm ocean ecosystems. Resources like the Monterey Bay Aquarium Seafood Watch guide provide up-to-date recommendations on the best choices based on sourcing. Seeking out wild-caught, small fish and farmed bivalves can significantly reduce your environmental footprint. For detailed information on sustainable practices, refer to the Monterey Bay Aquarium Seafood Watch guide.

Conclusion: Variety and Sourcing Matter

To achieve the maximum health benefits from seafood, the best strategy is to consume a variety of species from responsible sources. While options like wild Alaskan salmon, sardines, and oysters consistently rank high due to their combination of high omega-3s and low mercury, incorporating other low-mercury fish and shellfish ensures a broader spectrum of nutrients. Additionally, being mindful of sourcing by choosing smaller, wild-caught fish or sustainably farmed options will help protect your health and the environment. Limiting intake of large predatory fish like king mackerel and swordfish is a wise choice to minimize mercury exposure. By following these guidelines, you can confidently choose the healthiest and most beneficial seafood for your diet.

Frequently Asked Questions

Fatty fish typically contain the most omega-3 fatty acids. Top sources include mackerel, salmon, herring, sardines, and anchovies.

Smaller, shorter-lived species tend to have the lowest mercury levels. Some of the safest low-mercury options include sardines, anchovies, salmon, oysters, shrimp, and Atlantic mackerel.

Wild-caught salmon is often considered healthier due to being leaner and having fewer contaminants like PCBs. However, some farmed salmon can still be a nutritious choice, particularly if sustainably certified.

Yes, canned sardines are very healthy. They are packed with omega-3s and, when eaten with the bones, provide an excellent source of calcium. Opt for low-sodium versions packed in water or olive oil.

Yes, the FDA and EPA recommend that pregnant women and young children eat seafood, but they should choose low-mercury options like salmon, sardines, and shrimp. The benefits of omega-3s for a baby's brain and nervous system are significant.

It is best to limit or avoid large, predatory fish with high mercury content, including king mackerel, swordfish, shark, and bigeye tuna.

Many bivalves like oysters, mussels, and clams are among the most sustainable seafood options, as they filter water and have a low environmental impact. Small forage fish like sardines and anchovies are also highly sustainable choices.

Shellfish are rich in lean protein and provide high amounts of essential minerals such as zinc, iron, selenium, and copper, as well as vitamin B12.