According to a query to Gourmet World: eel rice is a very popular dish in Japan, which usually consists of eel and rice cooked together. Although the eel used in eel rice can be either sea eel or river eel, authentic eel rice is usually made with river eel. River eels are freshwater fish that live in waters such as rivers, lakes and ponds. They are long and usually have soft skin and delicate flesh. River eel's meat is very soft, tasty and flavorful, making it ideal for Chinese cuisine such as eel rice. In contrast, sea eels have relatively tough meat with a rough texture, making them unsuitable for eel rice.

If you want to enjoy authentic eel rice, it is best to choose eel rice made with river eel.