Why is the sushi fatty tuna called tuna?

The fatty tuna used for sushi is actually not a separate species of tuna. It's simply a specific part of the tuna fish.

Here's the breakdown:

* Tuna refers to a variety of fish in the Scombridae family.

* Fatty Tuna refers to the belly fat of some tuna species, particularly bluefin tuna (Hon Maguro).

So, the term "tuna" in "fatty tuna" is a reference to the type of fish from which the fatty meat comes, not a distinct species itself.

Here's why this specific part is prized:

* Fat Content: The belly region has a higher concentration of fat, making it incredibly rich and flavorful.

* Texture: This fat adds a buttery, melt-in-your-mouth texture.

* Umami: The fat contains high levels of umami, a savory taste that is considered delicious.

While other tuna species can be used for sushi, bluefin tuna is highly valued for its high fat content and delicious flavor.