What is the best kind of fish to have? A guide to optimal nutrition

October 17, 2025 •

4 min read

The American Heart Association recommends eating at least two servings of fish per week, especially fatty fish rich in omega-3s. Knowing what is the best kind of fish to have for your diet involves balancing nutritional benefits, potential risks like mercury, and sustainability practices.

Quick Summary

This guide helps you choose the healthiest fish by comparing omega-3 levels, mercury content, and sustainability. It covers excellent options like salmon and sardines while advising on varieties to limit for maximum health benefits.

Key Points

Prioritize fatty fish: Opt for salmon, sardines, and mackerel, which are rich in heart-healthy omega-3s.
Choose small, short-lived species: Smaller fish like sardines, anchovies, and Atlantic mackerel have significantly lower mercury levels due to their position in the food chain.
Consider canned options: Canned light tuna, salmon, and sardines are convenient, affordable, and retain excellent nutritional value, including bones for extra calcium in some cases.
Practice sustainability: Look for certifications from groups like the Marine Stewardship Council (MSC) to make eco-friendly seafood choices.
Know which fish to limit: Avoid frequent consumption of high-mercury species such as shark, swordfish, king mackerel, and bigeye tuna, especially for pregnant women and children.
Vary your fish intake: Eating a mix of different types of low-mercury, high-nutrient fish provides a wider range of vitamins and minerals.

The Nutritional Power of Fish

Fish is a cornerstone of many healthy diets, celebrated for its high-quality protein and abundance of vitamins and minerals. The primary health driver is the presence of omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These essential fats are crucial for heart health, reducing inflammation, lowering blood pressure, and supporting healthy brain function.

Additionally, fatty fish are one of the few natural food sources of vitamin D, a nutrient vital for bone health and immune function. Fish also provides other critical nutrients like iodine, selenium, B vitamins, and phosphorus. Regular consumption can help lower the risk of heart disease, stroke, and may even aid in managing blood sugar levels.

Key Factors for Choosing the Best Fish

When navigating the seafood counter, several factors should guide your decision to ensure you're making the healthiest and most responsible choice.

Balancing Nutrients and Contaminants

The main trade-off in selecting fish is between high-nutrient, omega-3-rich fatty fish and the potential for higher mercury levels. Generally, larger, longer-lived predatory fish tend to accumulate more mercury through bioaccumulation, while smaller, shorter-lived fish have lower levels. For most people, the health benefits of eating fish outweigh the risks, but high-risk groups like pregnant women and young children should be more cautious.

Understanding Farmed vs. Wild-Caught

Both farmed and wild-caught fish offer nutritional benefits, though their profiles can differ. Wild-caught fish often boast higher levels of omega-3s due to their natural diet. However, modern aquaculture practices have significantly improved, and many farmed fish are comparable in nutrition. Concerns about environmental impact and contaminants can apply to both wild fisheries (overfishing) and fish farms (pollution). The best approach is to research specific species and their origins.

Considering Sustainability

Sustainable fishing and farming practices are crucial for protecting marine ecosystems and ensuring fish stocks for the future. Look for certifications from reputable organizations like the Marine Stewardship Council (MSC) or use resources like the Monterey Bay Aquarium Seafood Watch guide. These labels and guides help you identify species caught or farmed responsibly, minimizing negative environmental impacts.

Top Contenders for the Best Fish

Based on a balance of high omega-3 content, low mercury, and sustainability, a few types of fish consistently rise to the top.

Salmon: A versatile and popular fatty fish, salmon is an excellent source of omega-3s, protein, and vitamin D. Wild Alaskan salmon is often cited as a highly sustainable choice, with well-managed fisheries. While wild-caught typically has higher omega-3s, responsibly farmed salmon is still very nutritious.
Sardines: These small, oily fish are true nutritional powerhouses. Because they are low on the food chain, they contain very little mercury. They are rich in omega-3s, protein, and provide a significant source of calcium and vitamin D if eaten with the soft, edible bones. They are also widely available and inexpensive, especially in canned form.
Mackerel: Similar to sardines, Atlantic mackerel is an oily fish packed with omega-3s, protein, and selenium. It has a lower mercury content than larger species and is often a very sustainable choice.
Trout: Farmed rainbow trout, particularly from the U.S., is another sustainable and nutritious option. It is a good source of omega-3s and vitamin B12.
Cod: A lean, flaky white fish, cod is lower in omega-3s than fatty fish but is high in protein and very low in mercury. It is a great choice for those seeking a mild flavor and lean protein source.

Fish to Eat in Moderation or Limit

To minimize mercury exposure, especially for sensitive populations, it is wise to limit or avoid certain species. These larger, longer-lived predatory fish accumulate more mercury over their lifespan.

Shark: High mercury levels.
Swordfish: High mercury levels.
King Mackerel: High mercury levels.
Bigeye Tuna: High mercury levels. Canned light tuna generally uses smaller skipjack tuna and has much lower mercury.

Comparison of Common Fish Choices


Fish	Omega-3 Content (per 3.5oz)	Mercury Level	Sustainability	Best For
Salmon	High (~2150mg)	Low	Wild Alaskan is excellent; choose responsibly farmed	Heart health, versatility, brain function
Sardines	High (~982mg)	Very Low	Wild-caught Pacific is excellent	Bone health (calcium), budget-friendly, brain function
Atlantic Mackerel	Very High (~4580mg)	Low	Wild-caught Atlantic is excellent	Inflammation, energy, immune support
Cod	Low (~111mg)	Low	Varies; check sourcing, Icelandic cod is a good choice	Lean protein, mild flavor, weight management
Canned Light Tuna	Good (~700mg)	Low	Varies; choose "pole and line" caught for best sustainability	Convenient, affordable protein
Bigeye Tuna	Good (~689mg)	High	Concerns due to overfishing and mercury	Limit consumption, especially high-risk individuals

Conclusion: Making the Right Choice

Determining what is the best kind of fish to have for your diet is a personal decision that requires considering a range of factors. For most people, the ideal choices are fatty fish like salmon, sardines, and Atlantic mackerel, which offer a great balance of high omega-3s, low mercury, and generally good sustainability profiles. Incorporating a variety of these low-mercury options into your diet two to three times a week is an effective way to reap the numerous health benefits. Remember to check sourcing labels for sustainable certifications and be mindful of high-mercury species, particularly for vulnerable individuals like pregnant women and children. This balanced approach ensures you can enjoy delicious, nutritious seafood while supporting your own health and the health of our oceans.

To learn more about fish and sustainability, consult the Monterey Bay Aquarium Seafood Watch guide (outbound link omitted due to policy).

Frequently Asked Questions

Fatty fish like mackerel, salmon, herring, and sardines are among the richest sources of omega-3 fatty acids, specifically the beneficial EPA and DHA.

Canned salmon and sardines are two of the healthiest choices. They are high in omega-3s and, when consumed with the bones, provide a great source of calcium. Canned light tuna is also a good, low-mercury option.

Yes, for most people, the benefits of eating fish outweigh the risks of mercury exposure, as long as you choose varieties that are low in mercury. Larger, predatory fish tend to have higher levels and should be limited.

The American Heart Association recommends eating at least two servings of fish per week. A serving is typically 3.5 ounces cooked.

The nutritional value is often very similar, with some variations depending on the species and farming practices. The key is to choose responsibly sourced fish, whether farmed or wild, to ensure sustainability and minimize contaminants.

Examples of fish with low mercury levels include salmon, sardines, shrimp, cod, Atlantic mackerel, and canned light tuna.

Yes, but they should be careful to only eat low-mercury fish. The FDA provides a list of 'Best Choices' that are safe for these groups to consume 2-3 servings per week, including salmon, shrimp, and canned light tuna.