What is the top healthiest fish to eat? A Deep Dive into Nutrition

October 19, 2025 •

4 min read

According to the American Heart Association, most adults should eat two servings of fatty fish per week. Our comprehensive guide explores what is the top healthiest fish to eat, focusing on omega-3 content, protein, and low mercury levels.

Quick Summary

This guide evaluates the healthiest fish based on nutritional value, including high omega-3 fatty acids, protein content, and low mercury levels. It provides comparisons of oily and lean fish, lists options to prioritize, and offers tips for smart and healthy seafood choices.

Key Points

Oily Fish are Best: Fatty, cold-water fish like salmon, sardines, and mackerel are the richest sources of heart-healthy omega-3s.
Prioritize Low Mercury: Small, short-lived fish such as sardines and anchovies contain the lowest mercury levels, making them safe for frequent consumption.
Variety is Key: Combining different types of low-mercury fish, both fatty and lean, ensures a broad spectrum of nutrients.
Canned is Convenient: Canned salmon and sardines offer an affordable, long-lasting, and highly nutritious option for quick meals.
Limit High-Mercury Fish: Avoid or limit consumption of large predatory fish like swordfish, king mackerel, and shark due to high mercury accumulation.
Cooking Matters: Opt for healthier cooking methods like baking, grilling, or broiling to maintain the nutritional integrity of the fish.

What Makes a Fish Healthy?

Determining the healthiest fish to eat involves more than just selecting a tasty fillet. The most nutritious options are typically rich in key nutrients while being low in environmental contaminants, primarily mercury. Two major factors stand out: omega-3 fatty acids and mercury content.

The Power of Omega-3 Fatty Acids

Omega-3s are essential fats, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), which the human body cannot produce on its own. These polyunsaturated fats are critical for:

Heart Health: Reducing triglycerides, lowering blood pressure, and reducing the risk of heart disease.
Brain Function: Supporting cognitive health, memory, and potentially reducing the risk of age-related brain loss and dementia.
Inflammation Control: Acting as a powerful anti-inflammatory agent, which is crucial for managing chronic diseases.

Understanding Mercury Levels

Mercury is a neurotoxin that can accumulate in fish, with larger, longer-lived predatory fish having the highest levels. It’s important to balance the benefits of omega-3s with concerns about mercury exposure, especially for pregnant women and young children. The FDA and EPA provide guidance on which fish are 'Best Choices,' 'Good Choices,' and 'Choices to Avoid'.

The Top Contenders: A Detailed Breakdown

While many fish offer excellent nutritional profiles, a few stand out for their exceptional health benefits, low contaminant levels, and affordability. Here are some of the top choices:

Salmon

Salmon is arguably the most popular and celebrated of the fatty fish, and for good reason. It’s an excellent source of omega-3 fatty acids, high-quality protein, and vitamins D and B12.

Wild vs. Farmed: Wild-caught salmon generally has a slightly higher omega-3 content, but responsibly farmed salmon can also be a healthy, sustainable, and affordable option.
Mercury: Salmon is consistently low in mercury, making it a safe choice for regular consumption.

Sardines

These small, oily fish are nutritional powerhouses. Because they are low on the food chain and short-lived, sardines contain very low levels of mercury. When eaten with the soft bones, canned sardines provide a significant dose of calcium and vitamin D.

Mackerel

Atlantic or Chub mackerel is another superb source of omega-3s, B vitamins, and selenium. It is important to distinguish smaller Atlantic mackerel from the larger King mackerel, which has high mercury levels and should be limited.

Herring

This oily fish is packed with omega-3s, vitamin D, and vitamin B12. Herring is often sold canned, pickled, or smoked, making it a convenient and affordable option. It is also low in contaminants.

Rainbow Trout

Often a more delicate-tasting alternative to salmon, rainbow trout provides a healthy dose of omega-3s, protein, and vitamin D. Much of the rainbow trout sold is responsibly farmed, offering a sustainable, low-mercury option.

Healthiest Fish Comparison Table

Here is a comparison of some of the healthiest fish, based on common serving sizes and available nutritional data.


Fish	Omega-3s (EPA+DHA per 100g)	Protein (per 100g)	Mercury Level	Key Nutrients
Sardines	~982mg	24.6g	Low	Calcium, Vitamin D
Atlantic Mackerel	~2,298mg	18.6g	Low	Vitamin B12, Selenium
Anchovies	~2,053mg	28.9g	Low	Calcium, Niacin
Salmon (Wild)	~2,150mg	21.2g	Low	Vitamin D, Vitamin B12
Trout (Rainbow)	~733mg	19.9g	Low	Vitamin D, Vitamin B12
Cod	~72mg	16.1g	Low-Medium	Vitamin B12
Light Canned Tuna	~270mg	25.5g	Low-Medium	Protein, Iron

Making Healthy Fish Choices

To maximize the health benefits of eating fish, follow these guidelines:

Consider the Cooking Method

How you prepare fish can significantly impact its healthfulness. Opt for grilling, baking, or broiling over deep-frying to keep the fat and calorie content low.

Prioritize Oily Fish

Make sure at least one of your weekly servings is a fatty, oily fish like salmon, sardines, or mackerel to get the maximum omega-3 benefits.

Choose Responsibly

Look for certifications like the Marine Stewardship Council (MSC) or Aquaculture Stewardship Council (ASC) to ensure you are purchasing sustainably sourced seafood.

Don't Overlook Canned Options

Canned fish like salmon, light tuna, and sardines are budget-friendly, convenient, and retain most of their nutritional value. Choosing light (skipjack) tuna over albacore minimizes mercury exposure.

Conclusion

While a variety of seafood offers excellent nutrition, the overall healthiest choice often comes down to a balance of high omega-3s and low mercury. Fish like wild salmon, sardines, and Atlantic mackerel are consistently at the top for their robust nutritional profiles and low contaminant levels. Choosing a mix of fatty and lean fish while being mindful of sourcing and preparation can help ensure you reap the full health rewards of a seafood-rich diet.

For more detailed information on omega-3 fatty acids and their health benefits, consult the National Institutes of Health.

Frequently Asked Questions

There is no single "absolute" healthiest fish, but salmon, sardines, and Atlantic mackerel are consistently top contenders due to their high omega-3 fatty acid content and low mercury levels.

Both wild-caught and responsibly farmed fish can be healthy options. Wild fish may have slightly higher omega-3s, but modern aquaculture can produce fish with comparable or even higher levels. It is best to prioritize sustainably sourced options regardless of method.

You should limit or avoid larger, predatory fish that accumulate high levels of mercury. These include King Mackerel, Shark, Swordfish, and Bigeye Tuna.

Yes, canned fish like salmon and sardines are just as nutritious as their fresh counterparts. In some cases, like canned sardines with bones, they offer even more calcium. Light canned tuna is a low-mercury option, while canned albacore has higher levels.

For most healthy adults, the American Heart Association recommends eating two servings of fish per week, with an emphasis on fatty fish.

Mild-flavored white fish like cod, tilapia, and haddock are excellent entry points for those new to seafood. While lower in omega-3s than oily fish, they are still a great source of lean protein and are low in mercury.

Yes, many shellfish are very healthy. Oysters are rich in zinc, and mussels provide iron and B12. Shrimp and scallops are also low in mercury, high in protein, and low in calories.