Are you ever left staring at the seafood counter, bewildered by which fish to pick for dinner? You’ve heard about the health benefits of eating fish, but you’re also worried about things like mercury or pollution. If you want to make the best choices for both nutrition and safety, you’re in the right place. This guide breaks down the healthiest fish you can eat—and which ones you should avoid—so that your next seafood meal supports your health!
Key Takeaways
- Omega-3 fatty acids (EPA and DHA) in certain fish are vital for brain, heart, and overall body health.
- Mercury levels and other contaminants can make some fish risky to eat, especially for pregnant women and children.
- Size, age, habitat, and farming methods influence a fish’s nutritional benefits and safety.
- Wise seafood choices mean prioritizing fish high in Omega-3 and low in mercury.
1. Why Omega-3 Fatty Acids in Fish Matter
Fish aren’t just a protein source; they’re nature’s top supplier of omega-3s—specifically, EPA and DHA. These essential fats do wonders for your body and mind:
- Brain & Nervous System: DHA is a building block for brain cells, the nervous system, and the retina, helping maintain sharp vision and robust cognitive function.
- Heart Health: EPA’s anti-inflammatory effects can reduce your risk of heart disease and help keep blood pressure and cholesterol levels in check.
Regularly eating fatty, wild-caught fish is one of the best natural ways to get these nutrients that your body can’t produce on its own.
2. Factors to Consider When Choosing Fish for Optimal Health
2.1. Mercury Levels
Some species—especially large, long-lived predators—build up higher mercury levels over time. That’s because as these fish eat smaller ones (that have already absorbed mercury from algae or polluted water), the metal accumulates in their bodies.
- The worst offenders: Tilefish (Mexican Gulf), swordfish, shark, and king mackerel top the charts for mercury content.
- Why it matters: Too much mercury can harm the brain and nervous system, particularly risky for developing babies and children.
2.2. Omega-3 Content
Not all fish are omega-3 superstars. Some (like sardines, salmon, and mackerel) are loaded, while others (like cod or mahi-mahi) have much less. Go for wild-caught options, which typically pack more omega-3 than farmed versions.
2.3. Protein Quality and Digestibility
Fish is considered a highly digestible protein source—usually easier on your stomach than red meats. Almost 20% of a fish’s weight is usable protein, supporting muscle, organ, and tissue health.
3. Fish You Should Never Eat (or Should Limit)
Some species are best avoided or severely limited due to high mercury or low nutritional value.
3.1. Tilefish (from the Gulf of Mexico)
These have the highest mercury content of all tested fish, making them especially dangerous for everyone, but especially kids and pregnant women.
3.2. Swordfish, Shark, and King Mackerel
Predatory, long-lived fish like these accumulate high levels of mercury through bioaccumulation. Overfishing and pollution also threaten these species, so it’s best to skip them altogether.
3.3. Tuna (Eat Sparingly)
While delicious and protein-rich, tuna can vary widely in mercury content—ranging from moderate to high. Most experts advise eating tuna no more than once every few weeks, and even less for young children and expecting mothers.
3.4. Orange Roughy (Eat Sparingly)
High mercury and slow growth (which means more years accumulating toxins) make orange roughy a poor option for regular meals. Limit it to very occasional consumption.
3.5. Mahi-mahi (High Mercury, Low Omega-3s)
Despite its popularity, mahi-mahi is high in mercury and relatively low in heart-healthy omega-3s. Farmed mahi-mahi can also carry more contaminants due to lower farming standards. If you eat mahi-mahi, do so rarely.
3.6. Cod (Low Omega-3s, Moderate Mercury)
Cod is low in omega-3s and can carry moderate amounts of mercury—especially if farmed. While better than the above, it’s far from the healthiest fish choice.
4. The Healthiest Fish to Eat
Fortunately, plenty of fish pack lots of omega-3 and barely any mercury. Here are the top picks for optimal wellness:
4.1. Sardines (High Omega-3s, Very Low Mercury)
These little fish are omega-3 powerhouses—about 1,500 mg per 100g serving! They’re also among the lowest in mercury and heavy metals. Opt for wild-caught sardines for the cleanest options.
4.2. Atlantic Mackerel (Highest Omega-3s, Moderate Mercury)
Atlantic mackerel stand out for their sky-high omega-3 content (up to 2,670 mg per serving) while keeping mercury levels low to moderate (about 50 parts per billion). Choose wild-caught.
4.3. Salmon (Top Omega-3s, Very Low Mercury)
Nothing rivals wild-caught salmon for its nutrients—offering over 2,500 mg omega-3 per serving and as little as 22 parts per billion mercury. Avoid farm-raised salmon, which has more contaminants and fewer omega-3s due to its artificial diet.
4.4. Herring (High Omega-3s, Moderate Mercury)
Herring is both flavorful and nutritious (almost 2,000 mg omega-3s per serving), with only moderate mercury levels. It’s safe for most adults but should be limited for pregnant women and children.
4.5. Croaker (Moderate Mercury, Good Omega-3s)
Croaker offers a balance between nutritional benefits and relatively low mercury. Include it occasionally as a varied part of your seafood diet.
5. Why Wild-Caught Beats Farmed Fish
Opt for wild-caught fish whenever possible. Here’s why:
- Fewer Contaminants: Farmed fish may contain higher levels of PCBs, pesticides, antibiotics, and other pollutants from their environments and feeds.
- Better Omega Fatty Acid Balance: Farmed fish eat grain-based diets, which skew their fat content toward unhealthy omega-6s and lower the heart-healthy omega-3s you want.
Farmed or imported fish that are not monitored closely may introduce even more unknown toxins into your diet.
6. A Word About Mercury Data—and Using Common Sense
Data about mercury levels in fish can be confusing and is not always up-to-date. Most official readings from agencies like the FDA were gathered between 1990 and 2010. Mercury levels in fish can also fluctuate based on size, age, specific body of water, and pollution trends—so guidelines are just that: guidelines.
When in doubt, opt for smaller, younger fish from wild sources and enjoy a variety of low-mercury seafood to spread out any risks.
Conclusion: Eat Smart for Optimal Health
Fish can be a terrific addition to a healthy diet—if you pick wisely! Let omega-3s and mercury levels be your guide next time you shop for seafood. Prioritize wild-caught fish like sardines, salmon, and mackerel, and avoid large, predatory species like tilefish and swordfish. Your brain, heart, and body will thank you with every bite.