The saltwater eel commonly used in sushi is called anago. In Japanese food terminology, anago usually refers to ma-anago, the Japanese conger eel, scientifically known as Conger myriaster.
Anago is commonly simmered until tender before being placed on sushi rice, although it can also be fried as tempura. Its flesh is soft, lightly sweet, and generally less oily than that of unagi. Sushi chefs may finish it with a sweet tare sauce.
The most important mix-up is between anago and unagi. Anago is a saltwater conger eel, while unagi refers to freshwater eel. Unagi is commonly grilled and glazed, producing a richer, oilier texture. Saba, another option in the choices, means mackerel and is a completely different fish.