Narezushi (熟れ寿司, "matured sushi") is a traditional form of fermented sushi. Skinned and gutted fish are stuffed with salt, placed in a wooden barrel, doused with salt again, then weighed down with a heavy tsukemonoishi (pickling stone). As days pass, water seeps out and is removed. After six months, this sushi can be eaten, remaining edible for another six months or more.[23] The most famous variety of narezushi still being produced is funa-zushi (made from fish of the crucian carp genus, authentically from C. auratus grandoculis (nigoro-buna) endemic to Lake Biwa), a typical dish of Shiga Prefecture.