A Nutritionist's Guide: What is the Healthiest Fish to Cook?

November 6, 2025 •

4 min read

According to the American Heart Association, eating fish twice a week can significantly improve heart health. But with so many options, you might wonder: what is the healthiest fish to cook? This guide explores the best fish choices for nutrition, taste, and sustainability.

Quick Summary

This guide covers the most nutritionally beneficial fish, weighing factors like omega-3 content, mercury levels, and sustainability. Learn about the best cooking methods, including baking, steaming, and poaching, for preserving nutrients and maximizing health benefits.

Key Points

Choose a variety: Incorporate both oily fish (for omega-3s) and lean white fish (for low mercury) into your diet for a balanced nutritional intake.
Prioritize oily fish: Fish like salmon, sardines, and mackerel offer the highest concentration of heart-healthy omega-3 fatty acids, which are essential for brain function and reducing inflammation.
Favor low-mercury options: Smaller, short-lived fish like sardines, trout, and cod contain significantly less mercury than larger predators, making them a safer choice for frequent consumption.
Use gentle cooking methods: Baking, steaming, and poaching are the healthiest ways to prepare fish, as they preserve nutrients and prevent the addition of unhealthy fats.
Check for sustainability: Look for certifications like MSC or ASC to ensure your fish is sourced responsibly and supports healthy marine ecosystems.
Limit high-mercury species: Reduce your intake of large fish like swordfish, king mackerel, and Bigeye tuna to minimize mercury exposure.

Fish is a powerful protein source, rich in essential nutrients that are vital for overall health. Beyond being an excellent alternative to red meat, it offers a diverse range of flavors and textures. However, not all fish are created equal, and how you prepare it can significantly impact its nutritional value. This article dives into the top fish varieties for a nutritious diet and explores the healthiest cooking methods to lock in their benefits.

The Top Contenders: What is the Healthiest Fish to Cook?

Choosing the healthiest fish involves considering its omega-3 fatty acid content, potential mercury levels, and the sustainability of its source. The best choices typically strike a balance between these factors.

Oily Fish: Rich in Omega-3s

Oily fish are packed with marine-based omega-3 fatty acids (EPA and DHA), which are crucial for brain, heart, and metabolic health.

Salmon: A nutritional superstar and one of the best sources of omega-3s and high-quality protein. Wild-caught salmon is often praised for its higher omega-3 levels, but sustainably farmed varieties are still a great option.
Sardines: These small, budget-friendly fish are loaded with omega-3s and are one of the best dietary sources of calcium and vitamin D, especially when eaten canned with their bones. Being low on the food chain, they have very low mercury levels.
Mackerel: Rich in healthy fats, protein, and selenium, which supports the immune system and thyroid function. Opt for smaller varieties like Atlantic mackerel to minimize mercury exposure.
Herring: A Nordic diet staple, herring contains high levels of omega-3s, vitamin D, and vitamin B12. It is typically low in contaminants.

Lean White Fish: Protein-Packed and Low in Mercury

For those who prefer a milder flavor or are watching their fat intake, lean white fish are an excellent choice. They are low in calories and fat while providing a significant amount of lean protein.

Cod: A British classic, cod is high in protein, low in fat, and a good source of B vitamins, especially B12. Its mild flavor makes it a versatile starting point for newcomers to seafood.
Rainbow Trout: A great alternative to salmon with a milder taste. It is an excellent source of vitamin D and omega-3s, particularly when sustainably farmed.
Pollock: A lean protein source often used in fish sticks. It is notably low in mercury and a good source of B vitamins.

Best Cooking Methods to Preserve Nutrients

The way you cook fish can either preserve or diminish its nutritional content. Gentle, low-fat cooking methods are generally the healthiest.

Baking: One of the easiest and healthiest methods, as it helps retain omega-3s and vitamin D with minimal added fat. You can bake it on its own or in a parchment paper parcel (en papillote) with herbs and vegetables for added moisture and flavor.
Steaming and Poaching: These are among the gentlest cooking methods, preserving moisture and nutrients without adding fats. Poaching can be done in water, broth, or wine to infuse flavor into the delicate fish.
Grilling: A healthy option that adds a smoky flavor and requires little oil. Cooking time is short, which helps retain nutrients. Use a marinade to reduce the potential for harmful compounds that can form at high temperatures.
Pan-Frying: A healthier alternative to deep-frying, requiring less oil. To maximize health benefits, use a heart-healthy oil like olive oil and avoid charring the fish.

Navigating Mercury and Sustainability

Larger, predatory fish tend to accumulate more mercury over their lifespan, which is a concern for vulnerable populations like pregnant women and young children. Sustainable sourcing is also a critical factor for protecting ocean ecosystems. Look for certifications from organizations like the Marine Stewardship Council (MSC) or Aquaculture Stewardship Council (ASC).

Comparison of Healthy Fish Options


Fish Type	Omega-3 Content	Mercury Level	Sustainability	Best Cooking Method	Notes
Sardines	High	Low	Good, fast-reproducing	Canned, baked, grilled	Excellent source of calcium and Vitamin D.
Salmon (Wild)	Very High	Low	Generally good (e.g., Alaskan)	Baked, grilled, pan-seared	Versatile and rich in omega-3s.
Cod (Icelandic)	Low	Low	Good	Baked, poached, steamed	Lean protein, mild flavor, good source of Vitamin B12.
Mackerel (Atlantic)	High	Low	Good	Broiled, baked, pan-seared	Flavorful oily fish; smaller size means less mercury.
Rainbow Trout (Farmed)	High	Low	Good (U.S. farms)	Baked, pan-fried, grilled	Milder flavor than salmon, good source of Vitamin D.

Fish to Consider Limiting or Avoiding

For optimal health, some fish are best consumed in moderation due to higher mercury levels or unsustainable practices:

High-Mercury Fish: Large, long-lived predators like swordfish, king mackerel, marlin, and certain types of tuna (Bigeye) should be limited, especially by pregnant women and young children.
Unsustainable Practices: Some fish, like Atlantic halibut, are vulnerable to overfishing. It is also important to be aware of the source of farmed fish, as some operations use practices that can harm the environment.

Conclusion: Making Informed Choices

For the best results, prioritize a variety of fish, opting for a mix of high-omega-3 options like sardines and salmon, and lean, low-mercury choices like cod and trout. To preserve the health benefits, stick to gentle cooking methods such as baking, steaming, and poaching, which prevent nutrient loss and avoid adding unhealthy fats. By paying attention to both the type of fish and how you prepare it, you can ensure a healthy and delicious meal every time. To further explore nutritional details, consider resources like the USDA's food database.

Frequently Asked Questions

Both wild-caught and farmed salmon are healthy and rich in omega-3s. Some sources suggest wild-caught may contain higher levels of omega-3s and have less exposure to certain contaminants, but sustainably farmed salmon remains a good option and is often more affordable.

Tuna is a great source of lean protein, but mercury levels vary by type. Canned light tuna (skipjack) is lower in mercury than albacore (white) tuna. It's best to limit intake, especially of higher-mercury varieties, and follow guidelines from health organizations.

Generally, larger and longer-living predatory fish higher up the food chain accumulate more mercury. Fish like swordfish, king mackerel, and Bigeye tuna are known to be high in mercury, while smaller fish like sardines, anchovies, and cod are low.

Steaming, baking, or poaching are the best methods for heart health. They require little to no added fat, preserving the fish's natural omega-3 content, which is beneficial for cardiovascular health.

Yes, canned fish like sardines and salmon are very healthy and convenient. Canned sardines, in particular, provide extra calcium from their edible bones. Look for varieties packed in water or olive oil and check for added sodium.

To prevent dry fish, use gentle methods like steaming, poaching, or baking en papillote (in parchment paper). For baking or grilling, ensure you do not overcook the fish and consider using a marinade or keeping the skin on to lock in moisture.

Yes, deep-frying significantly increases the calorie and fat content of fish, and the high temperatures can damage healthy omega-3 fatty acids. It is the least healthy cooking method and should be avoided in favor of baking, steaming, or grilling.