It’s no secret that adding fish to your diet helps improve your health; doctors and nutritionists have been singing the praises of our finny friends forever. But like the saying goes, there are a plenty of fish in the sea. Are some better than others?

Turns out, not all fish are the same. Nearly all fish are good for you, but some have more of the desirable omega-3 fatty acids that studies have shown help keep blood pressure and triglyceride levels in check while lowering your risk of heart disease and improving brain function.

The top five fish recommended by Seafood Health Facts are herring, salmon, mackerel, sardines and tuna — the wild bluefin kind, not the canned tuna. These varieties are distinguished by their darker flesh, which means a higher fat content.

Each of these fish provide around 1,500 milligrams of omega-3 per each 3 ounce cooked portion. The American Heart Association recommends 1,000 milligrams per day for people with coronary heart disease, and two meals of oily fish per week for those without heart disease. The Dietary Guidelines for Americans advise that eating 8 ounces or more of seafood each week will provide the recommended 250 milligrams per day. However, only 20 percent of Americans meet this goal. On average, we’re eating less than 4 ounces.

On the flip side of the fish front, experts recommend steering clear of certain species, which may contain harmful levels of mercury. These include shark, swordfish, tilefish and king mackerel.

If you don’t see yourself or your family adding more servings of fish to your weekly menu, try taking fish oil pills. They’re not as tasty as a fresh fish fillet, but they’re certainly easier to catch.