Koi live an average of 50 to 70 years, but can live over 200 years. The oldest koi on record is Hanako, a scarlet koi that died in 1977 at the age of 226.
Koi are ornamental varieties of the common carp. They are distantly related to goldfish, which were bred from a different species of carp. They were originally bred in Japan and spread to Europe and North America during the 20th century. They are cold-water fish, but they do not thrive at temperatures below 10 degrees Celsius. They are omnivorous feeders and accept a wide variety of foods. The main health threats to koi are the koi herpes virus and Rhabdovirus carpio. There is no treatment for either disease.