Which fish is the healthiest to eat? A comprehensive nutrition diet guide

October 13, 2025 •

4 min read

According to the American Heart Association, incorporating at least two servings of fish, especially fatty fish, per week is recommended for a healthy diet. But with so many options available, many people ask: Which fish is the healthiest to eat? The answer lies in balancing beneficial nutrients like omega-3s with factors like mercury content and sustainability.

Quick Summary

This guide examines the health benefits and potential risks associated with various fish types, focusing on omega-3 content, mercury levels, and sourcing. It provides a comparative look at popular options to help you make informed decisions for a healthier diet.

Key Points

Omega-3s are Key: Fatty fish like salmon, sardines, and mackerel are the best source of omega-3s, which are crucial for heart and brain health.
Small Fish, Low Mercury: Smaller, non-predatory fish like sardines and anchovies have the lowest mercury levels and are safe for more frequent consumption.
Check Sustainability: Look for third-party certifications like the Marine Stewardship Council (MSC) to ensure your seafood is sourced sustainably.
Cook Healthily: Healthiest preparation methods include baking, grilling, and steaming, which preserve nutrients without adding unhealthy fats.
Be Mindful of Predatory Fish: Larger, predatory fish such as swordfish and bigeye tuna contain higher levels of mercury and should be limited.
Mix It Up: Eating a variety of low-mercury fish helps you get a broader range of nutrients and reduces your risk of excessive mercury exposure.

Understanding the Nutritional Benefits of Fish

Fish and seafood are nutritional powerhouses, providing high-quality protein, essential vitamins, and minerals. The star players, however, are the long-chain omega-3 fatty acids (EPA and DHA), which are vital for brain and heart health and have anti-inflammatory effects. Omega-3s are found in all fish, but are most abundant in 'fatty' or 'oily' varieties.

The Importance of Omega-3s

Omega-3 fatty acids are a type of essential fat that the human body cannot produce on its own. These polyunsaturated fats are crucial for numerous bodily functions and offer significant health benefits.

Heart Health: Omega-3s can help reduce the risk of cardiovascular disease by lowering blood pressure, reducing triglycerides, and decreasing the risk of heart attacks and strokes.
Brain Function and Development: DHA, one of the primary omega-3s, is essential for brain and nerve development, especially during pregnancy and early childhood. It may also help lower the risk of dementia and depression.
Reducing Inflammation: The anti-inflammatory properties of omega-3s can help manage and reduce symptoms associated with chronic inflammatory conditions, such as arthritis.

The Mercury Factor

One of the most significant concerns regarding fish consumption is mercury contamination. Mercury is absorbed by fish from the water and accumulates in their bodies, a process called biomagnification. Higher-mercury fish are typically large, predatory species that live longer, as they have more time to accumulate the toxin. Pregnant or breastfeeding women and young children should be especially careful to limit their intake of high-mercury fish.

The Healthiest Fish Choices

When selecting the healthiest fish, it's important to consider the balance of high omega-3 content and low mercury levels. Here are some of the top contenders for your plate.

Sardines: Often called one of the healthiest fish, sardines are small, oily, and low on the food chain, resulting in very low mercury levels. They are a phenomenal source of omega-3s, and when canned with bones, provide a significant boost of calcium and vitamin D.
Salmon: A popular choice, salmon is an excellent source of high-quality protein and heart-healthy omega-3s. While both wild and farmed salmon offer benefits, wild varieties can have slightly higher omega-3 levels. Salmon has a low mercury risk, making it a safe choice for regular consumption.
Mackerel: Atlantic mackerel is a great option, known for being rich in omega-3s, protein, and selenium. Due to concerns about mercury, Atlantic mackerel is a better choice than larger varieties like King mackerel.
Trout: Particularly farmed rainbow trout, is another excellent source of omega-3s and vitamin D with low mercury levels. Its milder flavor makes it a good alternative for those who don't enjoy the stronger taste of salmon.
Herring: A small, oily fish, herring is loaded with omega-3s, vitamin D, and vitamin B12. It's a sustainable choice that can be enjoyed in various forms, including fresh, canned, or smoked.

The Healthiest vs. Riskiest Fish

Not all fish are created equal when it comes to nutritional benefits and potential risks. The following table provides a quick comparison of some common fish varieties.


Fish Type	Omega-3 Content	Mercury Levels	Sustainability	Best For	Considerations
Sardines	Very High	Very Low	Generally high, look for MSC certified.	Heart and bone health.	Bold flavor, best when canned with bones.
Salmon	High	Low	Varies by source; look for wild-caught or sustainable farmed options.	Brain and heart health, high protein.	Wild may have higher omega-3s.
Atlantic Mackerel	High	Low	Generally good, look for MSC certified.	Immune support, energy.	Avoid larger, high-mercury King mackerel.
Tuna (Canned Light)	Medium	Low	Skipjack variety is generally sustainable.	Quick, high-protein meals, budget-friendly.	Limit consumption of higher-mercury albacore.
Cod	Low	Low	Good options exist, especially Icelandic.	Lean protein, low calorie.	Lower omega-3 content compared to fatty fish.
Halibut	Medium	Medium-High	Varies; categorized as a 'good' choice by FDA.	Lean protein, grilling.	Higher mercury, limit intake to once per week.
Swordfish	High	Very High	Overfishing and high mercury levels are concerns.	Flavorful, firm texture.	Best to avoid or consume very rarely due to high mercury.

Making Sustainable and Health-Conscious Choices

Beyond nutritional content and mercury, the environmental impact of your seafood choices is another important consideration. Overfishing and harmful fishing practices can deplete marine populations and damage ecosystems. Choosing sustainably sourced fish helps protect our oceans.

How to Choose Sustainable Seafood

Look for Certifications: Organizations like the Marine Stewardship Council (MSC) provide certification for sustainably sourced seafood.
Support Lower Trophic Levels: Eating smaller, forage fish like sardines and anchovies is often more sustainable as they reproduce quickly and are lower on the food chain.
Be Mindful of Farming: While aquaculture can relieve pressure on wild stocks, it can also raise environmental concerns related to pollution and disease. However, well-managed, certified fish farms (like those with Aquaculture Stewardship Council certification) can be a good option.

Preparing Fish for Maximum Benefit

How you cook your fish can also affect its health profile. Baking, grilling, and steaming are healthier cooking methods than deep-frying, which adds calories and unhealthy fats. Serving fish with a side of vegetables and healthy grains creates a balanced and nutrient-rich meal.

Conclusion

Deciding which fish is the healthiest to eat? requires balancing a few key factors: high omega-3 content, low mercury levels, and sustainable sourcing. Small, oily fish like sardines, mackerel, and salmon are excellent choices that deliver on all three fronts. While larger, predatory fish like swordfish are often high in nutrients, their high mercury content means they should be eaten less frequently, if at all. By making informed decisions about the fish you consume, you can maximize the health benefits for both yourself and the planet.

For more information on sustainable seafood, consider visiting the Marine Stewardship Council website.

Frequently Asked Questions

The primary benefit is the high content of omega-3 fatty acids, especially EPA and DHA, which are crucial for heart and brain health, and have anti-inflammatory effects.

Larger, predatory fish such as shark, swordfish, king mackerel, and bigeye tuna typically contain the highest levels of mercury and should be consumed in moderation or avoided.

Yes, many canned fish options like light tuna and sardines are healthy and convenient choices, offering good protein and omega-3s. For canned tuna, choosing 'light' skipjack varieties minimizes mercury intake.

Farmed fish, like sustainably farmed salmon and trout, can be a healthy option and an important source of omega-3s. It's best to look for ethically produced, certified farmed fish.

Some of the best low-mercury fish for regular consumption include salmon, sardines, trout, anchovies, herring, and canned light tuna.

The American Heart Association recommends eating at least two servings of fish per week, with an emphasis on oily or fatty fish, to get an adequate intake of beneficial omega-3s.

Yes, opting for healthier cooking methods like baking, grilling, or steaming is best. Deep-frying can add significant unhealthy fats and calories, which diminishes the overall health benefits.