Koi fish have a typical life span ranging from 50 to 70 years. There are authenticated cases, however, in which koi have lived over 200 years.
While most koi do not reach the exceedingly long life span sometimes attributed to the species, the oldest koi fish lived to be 226 years old. This fish, named Hanako, died on July 7, 1977, according to Mother Nature Network. Koi typically grow to reach 2 to 3 feet long and weigh approximately 35 pounds. They are a species of common carp fish bred through the centuries by Japanese rice farmers to have the color variations they are known for today.