At 226 years old, koi Hanako was the longest living freshwater fish ever recorded. Koi Hanako was a beautiful scarlet coloured female Nishikigoi in Japan. Her name Hanako is translated “flower girl” in Japanese. Hanako died in July 7, 1977 at a grand old age of 226. Born in 1751, Hanako was born in the first year of Horeki, in the middle of the Tokugawa Era. This makes Hanako older than the United States of America!
In May 25 1966, Dr. Komei Koshihara, the last owner of koi Hanako, made a broadcast to the whole Japanese nation through Nippon Hoso Kyokai radio station about the story of koi Hanako. At this time, Hanako was 215 years old weighing 7.5 kilograms and 70 centimeters long. He explained that the koi was passed down from his grandmother on his maternal side, who had inherited the fish from “olden times.” Dr. Koshihara described Hanako as his dearest friend.
Hanako’s actual age was verified by analyzing the rings on her scales. Much like how dendrologists determine the age of trees by counting the number of rings of growth on wood, the rings of growth on the scale of Hanako was counted using a light microscope. The growth rings on the scale shows a pattern of wide growth followed by a narrower growth. The differences in the width of the rings reflect the seasonal change of summer and winter. During the summer, fish eat more and grow more resulting in a wider growth ring pattern. The narrower growth represents the slower metabolism during the cold icy weather. In order to analyze the exact age of Hanako, she was extracted from the pond in the deep mountains of Mino Province. Two scales from different parts of her body were taken off with tweezers. The individual annual ring on the scale was painstakingly analyzed over a period of two months in Laboratory of Animal Science, Nagoya Women’s College by professor Masayoshi Hiro. Both Dr. Koshihara and Professor Hiro were delightfully surprised when Hanako was discovered to be 215 years old at the time. Following this discovery, the remaining five koi carp in the same pond was examined as well. After a yearlong analysis, the results showed that they were all over 100 years old as well.
While nobody knows the exact reason for her amazingly long lifespan, perhaps the crystal clear waters of the Japanese mountains in addition to the great love and care of her owners was the key. Koi carp is generally a long-lived fish with a lifespan of approximately 50 years. However, there are many carp that lives over a century. This is one of the reasons why the koi carp have gained so much admiration in Japan and the rest of the world as well. Koi Hanako, is a great example of the how long living koi carps truly are. In fact, she is the longest living freshwater fish ever recorded. However, next to whales, turtoises, and tuataras, koi are one of the longest living vertebrae on Earth.