The levels of protein in fish are high, making them a good source of this macronutrient while also supplying essential minerals and heart-healthy omega-3 fatty acids. However, it's important to limit intake of larger fish like shark and swordfish, as they may contain high levels of mercury.
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According to the National Academies of Sciences, the recommended daily allowance (RDA) for protein for adult females is 46 grams, while the RDA for adult males is 56 grams. In addition to fish, other foods that represent excellent sources of dietary protein include cheese, beans, lean red meats, seeds, poultry, yeast extract and legumes.
Read more: 7 Fish Recipes That Are Great for Your Heart
Eat Tuna for Protein
Tuna has the highest protein content compared to other types of fish. The bluefin and yellowfin species of tuna are especially high in protein, with bluefin offering up 29.91 grams of protein per 100 grams of dry-cooked fish, and yellowfin providing 29.15 grams, according to the USDA. Canned light tuna, usually made from a blend of yellowfin and skipjack tuna, is also an excellent source of protein, supplying 29.13 grams of protein per 100 grams, according to the USDA.
Protein in Other Fish
Besides tuna, other fish with high protein content, ranging from about 26 to 29 grams per 100-gram serving, according to the USDA, include: anchovies, salmon, halibut, snapper and tilapia. Swordfish and cod also contain high amounts of dietary protein, each providing about 23 grams per 100 grams of fish.
Lobster and other shellfish are good sources of protein as well, with lobster supplying 26.41 grams per 100 grams. Shrimp and crab meat are other high-protein sea crustaceans. While usually consumed in smaller amounts than fish flesh, fish eggs are also very protein-dense, offering about 29 grams of protein per 100 grams.
Read more: 13 Types of Fish to Avoid Eating
Be Aware of Mercury Levels
It's important to choose wisely when selecting high-protein fish in order to limit mercury exposure risk. While providing the highest protein content in fish, bluefin tuna, primarily consumed in sushi dishes, has been associated with high mercury levels. Light canned tuna, on the other hand, while providing only slightly less protein than bluefin, has relatively low levels of mercury, according to the American Heart Association (AHA). Shrimp, salmon, cod and crab are also low in mercury, while swordfish and snapper contain higher amounts of mercury.
Follow These Recommendations
The AHA recommends eating at least two servings of fish per week, choosing mostly omega-3-rich, low-mercury fish like salmon and tuna — both of which are also high in protein. As an added health benefit, omega-3 fatty acids in fish have also been shown to reduce risk of heart disease.
Pregnant women and children should be especially careful to limit their fish intake to low-mercury fish and should not exceed two 6-ounce servings of fish per week. In addition to fish, Mayo Clinic Health System also recommends eating other high-protein foods, such as tofu, soybeans, walnuts and flaxseed.
- American Heart Association: "Fish and Omega-3 Fatty Acids"
- USDA National Nutrient Database: "Protein: Fish and Shellfish Products"
- Mayo Clinic Health System: "Are You Getting Too Much Protein?"
- The National Academies of Sciences: "Macronutrients"
- "The New York Times"; High Mercury Levels Are Found in Tuna Sushi; Marian Burros; January 2008