Koi

• GeneralBred selectively in Japan since the 19th century; some fish have been credited with over 200 years.
• Koi breeding began in the nineteenth century among the farmers of the Niigata region, who raised carp in their rice paddies and started setting aside the fish with coloured markings.
• The age of 226 years attributed to the Japanese koi Hanako was worked out from the rings on a scale and is very widely quoted, but it has never been independently verified.
• It can survive under the ice with its metabolism almost at a standstill and tolerate oxygen levels that would be lethal to most fish.
• The koi is not a species: it is an ornamental variety of the Asian carp, selected for its colour from the 19th century onwards in the Japanese region of Niigata, among rice growers who kept them in their irrigation ponds.
• For a long time it was attributed to the European ancestor Cyprinus carpio; today it is accepted that the koi derives from the East Asian carp, Cyprinus rubrofuscus, a distinct species.
• Its longevity gives rise to a fair amount of mythology. A specimen called Hanako is often cited as having lived for more than two hundred years, but that figure comes from the reading of a single scale and has not been independently confirmed. Well-cared-for koi usually live between twenty and fifty years.
• Released into the wild, it behaves like any carp: it stirs up the bottom as it feeds, clouds the water and degrades submerged vegetation.

Skeleton type

Vertebrate - internal bony skeleton (bony fish)

Habitat and environment

Ornamental ponds, lakes and canals

Sources consulted: https://es.wikipedia.org/wiki/Cyprinus_rubrofuscus; Movement Ecology 2023 y NCBI PMC8901867, comportamiento social de Cyprinus