1. Different species: Tuna and marlin have different species. Although they belong to Perciformes, they belong to different families. Tuna belongs to the mackerel family, and marlin belongs to the swordfish family. There are great differences in species between the two kinds of fish.

2. Different shapes: Marlin and tuna also have very different shapes. Although they are both large fish, tuna will have metallic luster on both sides of the body, while marlin does not. The second most obvious thing is the mouth. Tuna's mouth is round and its snout is short. Marlin has a sharp mouth and a very long snout. Some marlin kiss length can even reach one fifth of the body.

1. Different shapes: Tuna is round, but the part where the tail connects with the body is thin. The overall shape of salmon is smooth, but the body is flat.

2. Different living environments: Tuna likes to live in warm sea areas, and they often live in low latitude sea areas such as Pacific Ocean, Atlantic Ocean and Indian Ocean. Salmon like to live in cooler waters, so they are mostly distributed in the Arctic Ocean and the northern Pacific Ocean.

3, different meat quality: Tuna tastes better because it has less fat content, and it tastes very good whether eaten raw or cooked. Although salmon is also a high-grade food, its taste and nutritional value are lower than tuna.