At 226 years old, koi Hanako was the oldest koi fish ever recorded. Koi Hanako was a beautiful scarlet-colored female Higoi in Japan. Her name Hanako is translated as “flower girl” in Japanese. In 1751, Hanako was born in the first year of Horeki, in Japan’s middle of the Tokugawa Era. Hanako died on July 7, 1977, at the grand old age of 226. This made Hanako not only the oldest koi but also the longest-living freshwater fish to ever exist on record. This record has yet to be surpassed to this day.
Koi Hanako’s Age (Oldest Koi Fish)
Hanako’s actual age was verified by analyzing the rings on her scales. Much like how dendrologists determine the age of a tree by counting the number of rings of growth on the wood, the annual growth rings on the scale of Hanako were counted using a light microscope. The growth rings on the scale show a pattern of wide growth followed by narrower growth.
The differences in the width of the rings reflect the seasonal change of summer and winter. During the summer season, fish eat more and grow more, resulting in a wider growth ring pattern. The narrower growth represents the slower metabolism during 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 growth rings on the scales were painstakingly analyzed over a period of two months by professor Masayoshi Hiro of Laboratory of Animal Science, Nagoya Women’s University.
Professor Hiro and Dr. Komei Koshihara, the last owner of koi Hanako, were both 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 were examined as well. After a yearlong analysis, the results showed that the other fish in the pond were also over 100 years old.
On May 25, 1966, Dr. Komei Koshihara broadcasted 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. While nobody knows the exact reason for her amazingly long lifespan, perhaps the crystal clear waters of the Japanese mountains and the great love and care of her owners were the contributing factors.
Koi Lifespan: How Long Do Koi Fish Live?
In general, koi fish are known to have long lifespans. While it can vary widely, the average lifespan of a koi fish is 25-35 years. Their lifespan is affected by various environmental and genetic factors. In the wild, koi fish may not live as long due to unfavorable conditions.
There are often eaten by other fish and animals in the wild. In captivity, the average lifespan of a koi fish can be longer. It is not rare for koi fish to live for over 70 years in good conditions. In fact, it is quite common to witness koi that are over a century old in Japan. Their long lifespan is one of the reasons why koi fish have gained so much admiration worldwide.
Environmental factors contributing to a long lifespan are clean water, a good pond filter, quality koi food, and long cold winters. The cold season will slow down the koi’s metabolism drastically. During this period, the fish may eat very little. In fact, during the coldest winter months, it is recommended to stop feeding completely, as described in the Koi Feeding Guide.
Genetic factors also play a significant role in a koi’s potential lifespan. In Japan, these ornamental carp are called Nishikigoi. They are bred for specific traits such as their body shape and coloration. Of course, the large size is desirable, but only if the body shape and coloration are maintained.
Outside of Japan, koi are often bred for different characteristics. For example, the popular butterfly koi are bred to be much hardier and exhibit faster growth. Therefore, koi fish that live over 200 years, like Hanako, is extremely rare.
Next to whales, tortoises, and tuataras, koi fish are one of the longest-living vertebrae on Earth. Koi Hanako is a great example of how long koi fish can actually live. In fact, she is the longest-living freshwater fish ever recorded.