The average life expectancy for koi fish outside of Japan is about 15 years, while its 40 years in Japan. Reportedly, koi fish can live for much longer in the optimal conditions and there are supposedly many koi who live over 100 years. For the most part these are just rumours and most koi only live for a few decades. However, the oldest koi on this list lived for over 200 years and had its age scientifically verified.
Hanako (c. 1751 – July 7, 1977)
Oldest Age Reached: 226 years old in 1977
Location: Higashi-Shirakawa Village, Japan
Owner(s): Dr. Komei Koshihara
Hanako is probably the most famous koi fish ever in history due to her astonishing age. When Hanako died in 1977 she was believed to be 226 years old, making Hanako the oldest koi fish ever in the world.
Hanako’s amazing story was first brought to light when her last owner, Dr. Komei Koshihara, made a national broadcast on Nippon Hoso Kyokai radio station to all of Japan. Dr. Koshihara explained how he had inherited Hanako from the maternal side of his family. At the time of the broadcast, Hanako was 215 years old, weighed 7.5 kg (16.5 lbs), and was 70 cm (27.6 in) long.
Dr. Koshihara knew Hanako’s age because he had it verified by professor Masayoshi Hiro who worked at the Laboratory of Animal Science of the Nagoya Women’s College. Two of Hanako’s scales were extracted and analyzed for two months. Professor Hiro was able to count the rings of growth on Hanako’s scales to determine her age.