Traditional fermented sushi is called narezushi. After the skin and guts have been removed, the fish is salted, placed in wooden barrels, sprinkled with salt again, and pressed with large salt stones. Water leaked out, but was cleared in a few days. This sushi can be eaten after half a year and can continue to be eaten for at least another half a year. [36]
The most famous cooked sushi is a specialty of Shiga Prefecture[37], especially funazushi, which uses crucian carp fish, uses nigorobuna, an endemic wild species that inhabits Lake Biwa, which is necessary for genuine crucian carp. [38]