Tuna has more protein than salmon. Per 100 grams of cooked fish, bluefin tuna delivers about 23 grams of protein compared to 20 grams in Atlantic salmon. That 3-gram difference comes down to fat content: tuna is a much leaner fish, so more of its weight is pure protein.
Protein by the Numbers
According to USDA data, 100 grams of cooked bluefin tuna contains 23 grams of protein, 5 grams of fat, and 144 calories. The same amount of Atlantic salmon contains 20 grams of protein, 13 grams of fat, and 197 calories. Tuna gives you roughly 15% more protein while carrying about 27% fewer calories, making it the more protein-dense option by any measure.
If you think in terms of protein per calorie, tuna pulls further ahead. You get about 0.16 grams of protein for every calorie of tuna, versus 0.10 grams per calorie of salmon. For anyone tracking macros on a calorie budget, that gap matters.
Protein Varies by Species
Not all tuna is the same. A 6-ounce fillet of cooked yellowfin tuna packs nearly 50 grams of protein, and a 3-ounce serving of skipjack (the kind in most canned “light” tuna) has about 24 grams. Yellowfin and skipjack are among the leanest varieties, so their protein-to-weight ratio is especially high.
Salmon varies less between species. Sockeye, Atlantic, and king salmon all hover around 20 to 22 grams of protein per 100 grams, with fattier species like king salmon sitting at the lower end because more of the fillet’s weight comes from fat.
Amino Acid Quality
Both fish are complete proteins, meaning they contain all nine essential amino acids your body can’t make on its own. But tuna edges ahead in concentration. In a 6-ounce serving of bluefin tuna, you get about 4,133 milligrams of leucine, the amino acid most important for triggering muscle repair and growth. The same serving of sockeye salmon provides 3,715 milligrams. Tuna also delivers more lysine (4,670 mg vs. 4,376 mg) and more isoleucine (2,343 mg vs. 2,166 mg). Tryptophan is the only essential amino acid where the two fish are equal.
In practical terms, both fish supply more than enough of every essential amino acid per serving. The difference only becomes meaningful if you’re trying to maximize leucine intake for muscle-building goals on limited total food volume.
What Salmon Offers That Tuna Doesn’t
Choosing the highest-protein option isn’t always the whole story. Salmon is classified as an oily fish, which means it’s one of the best natural sources of long-chain omega-3 fatty acids. These are the fats linked to heart health, reduced inflammation, and brain function. Salmon is also a strong source of vitamin D, a nutrient many people are low in.
Tuna, despite being a fish, does not count as oily fish. The NHS specifically notes this distinction: if you eat tuna in a given week, it doesn’t count toward your recommended servings of oily fish. That 13 grams of fat in salmon that “costs” it 3 grams of protein per serving is largely omega-3 fat that carries its own health benefits. So the trade-off is real: tuna wins on protein and leanness, salmon wins on healthy fats and micronutrients.
Mercury Is a Factor for Tuna
Mercury levels are worth considering if you plan to eat tuna frequently for its protein advantage. The FDA categorizes salmon as a “Best Choice” fish, meaning it’s low in mercury and safe to eat two to three servings per week. Tuna is more complicated because mercury varies dramatically by species.
- Canned light tuna (skipjack): Best Choice, low mercury
- Albacore/white tuna: Good Choice, moderate mercury, eat no more than one serving per week
- Yellowfin tuna: Good Choice, moderate mercury
- Bigeye tuna: Choice to Avoid, highest mercury levels
For pregnant or breastfeeding women, the FDA recommends no more than four cans of tuna or two tuna steaks per week. If you’re eating tuna daily for the protein content, skipjack is the safest bet. Salmon has no such restrictions.
Which to Choose for Your Goals
If your primary goal is maximizing protein while minimizing calories and fat, tuna is the better pick. A can of skipjack tuna is one of the most protein-dense, affordable foods available, and it’s low enough in mercury to eat several times a week. For bodybuilders, people in a calorie deficit, or anyone simply trying to hit a protein target, tuna delivers more per bite.
If you want a well-rounded nutritional profile with strong omega-3 content, salmon is the smarter choice overall, even though it carries slightly less protein per serving. The 3-gram protein difference per 100 grams is easy to make up elsewhere in your diet. The omega-3 and vitamin D content of salmon is harder to replace.
Plenty of people rotate both. Canned skipjack tuna for quick, lean, high-protein meals a few times a week, and salmon once or twice for the omega-3 benefits. That combination gives you the protein advantage of tuna and the nutritional depth of salmon without pushing mercury levels into concerning territory.