Differences between Salmon and Tuna

Differences between Salmon and Tuna

Salmon and tuna are two widely consumed types of fish, both known for their nutritional value. Although they are both popular seafood choices, they belong to different biological families and exhibit distinct characteristics in terms of their habitat, diet, physical appearance, and nutritional composition. Tuna are saltwater fish from the Scombridae family, which also includes mackerels and bonitos. Salmon belong to the Salmonidae family, which includes trout and char.

Comparison Table

Category	Salmon	Tuna
Scientific Family	Salmonidae	Scombridae
Habitat	Anadromous; born in fresh water, migrates to the ocean, and returns to fresh water to reproduce.	Primarily a saltwater, open-ocean fish found in temperate and tropical waters worldwide.
Appearance	Robust body, rounded fins, and pink-to-reddish-orange flesh due to a diet rich in astaxanthin. The color remains even when cooked.	Elongated, streamlined body built for speed, with long, angular fins. Flesh color ranges from pink to dark red, which turns grayish-white when cooked.
Flavor and Texture	Rich, buttery, and slightly sweet flavor with a tender, oily texture.	Milder, more savory flavor with a firm, lean, and sometimes steak-like texture.
Omega-3 Fatty Acids	Higher content, with wild salmon providing around 1.1 to 1.7 grams per 3-ounce serving.	Lower content than salmon, though still a good source. A 3-ounce serving of yellowfin tuna has around 91mg.
Protein Content	High in protein, with a 3.5-ounce serving of wild salmon containing about 20 grams.	Slightly higher in protein than salmon; a 3.5-ounce serving of raw tuna has about 23 grams.
Vitamin D	Excellent source of vitamin D.	Contains less vitamin D than salmon.
Mercury Levels	Generally very low levels of mercury.	Higher mercury levels, which vary by species. Larger species like bigeye and albacore contain more than smaller species like skipjack.

Venn diagram comparing Differences between Salmon and Tuna

Habitat and Life Cycle

A primary difference lies in their habitats. Most species of salmon are anadromous, meaning they are born in freshwater streams, migrate to the saltwater ocean to mature, and then return to their natal streams to spawn. In contrast, tuna are exclusively marine fish that live their entire lives in the open ocean, often in large schools, and are found in temperate and tropical seas across the globe. Tuna are built for speed, with streamlined bodies that allow some species, like the yellowfin, to reach speeds of up to 75 km/h.

Nutritional Profile

Both fish are highly nutritious, but their profiles differ. Salmon is known for its high content of omega-3 fatty acids, which are beneficial for heart and brain health. It is also one of the few natural food sources rich in vitamin D. Salmon has a higher fat content and more calories than tuna.

Tuna is leaner, with a higher protein and lower calorie content compared to salmon, making it a common choice for low-fat diets. While it contains omega-3s, the concentration is generally lower than in salmon. On the other hand, tuna provides more selenium and niacin (Vitamin B3) than salmon. Due to their position higher up the food chain and longer lifespan, larger species of tuna tend to accumulate higher levels of mercury than salmon. The U.S. Food and Drug Administration advises that pregnant women and young children should limit their consumption of certain types of tuna due to mercury content, while salmon is listed as a "Best Choice" with low mercury levels.

Culinary Characteristics

In the kitchen, their differences in taste and texture dictate their uses. Salmon has a rich, buttery flavor and a tender, flaky texture due to its higher fat content. This makes it suitable for grilling, baking, and smoking. Tuna has a milder flavor and a much firmer, denser texture, similar to steak. This firmness allows it to be seared or grilled as steaks and is why it is frequently used raw in dishes like sashimi and poke bowls.