【Reading】ぎんぶな

【English Name】Ginbuna (Silver Crucian Carp)

Gin-buna, belonging to the family Cyprinidae, genus Carassius, is a freshwater fish that has established itself widely centered on ponds, marshes, and slow-flowing downstream reaches. Its distribution is not limited to within Japan; wild individuals have been recorded in Taiwan, the Korean Peninsula, and China, and cases of introduction to Europe and North America have also been reported.

The body length of a standard adult is from the mid-15 cm range to around 20 cm, with large individuals growing close to 30 cm also existing. The dorsal side is a greenish-tinged brown, and a guideline for identification is that its body is lower than that of gengoro-buna and higher than that of kin-buna.

This fish's biological distinction lies in its mode of reproduction. Wild populations are composed almost entirely of females and reproduce through a form of asexual reproduction called gynogenesis. Sperm released by males of other crucian carp species function not as fertilization but as a stimulus for egg development, and the juveniles born are genetically identical clones of the mother. The chromosome number is basically 150, taking a triploid structure.

It is a fish that has historically been familiar on tables throughout Japan, and around Hachirogata in Akita Prefecture it is still eaten today as a winter local food. In parts of Nagano Prefecture, aquaculture using agricultural reservoirs is still practiced, and diverse ways of eating—salt-grilling, kanro-ni (sweet simmering), sashimi, and arai—have been handed down. However, because it can serve as an intermediate host for the gnathostome (yu-kyoku-gakko-chu), thorough hygiene management is required when eating it raw.

In the sushi context, its connection to funa-zushi, the traditional fermented food of Shiga Prefecture, draws attention. Originally nigoro-buna is the raw material, but in response to resource decline, a method using gin-buna as a substitute is practiced in some regions.