An essential ingredient in sushi and tempura is the conger eel. The conger eel, also known as Anago in Japanese, is commonly referred to as the sea eel. "Anago" originates from its habit of spawning in crevices between rocks or sandy areas.

Although conger eels and freshwater eels (unagi) have a similar appearance, conger eels have white spots along their sides and fewer scales. Unlike the rich and oily flavour of freshwater eels, conger eels have a milder taste due to their lower fat content. In the Kanto region of Japan, conger eels are commonly prepared as "Nianago" (simmered conger eel) or "Tenpura" (tempura). In contrast, in the Kansai region, they are often grilled and known as "Yakianago" (grilled conger eel).