The Koi Lifespan and Why Japanese Koi Live Longer
Owning koi fish can be a huge commitment, not because they are high maintenance (the only pet that is lower maintenance is a pet rock) but because of how long the koi lifespan is. The average koi breed outside of Japan can be expected to reach fifteen years of age, but the average Japanese koi's lifespan is forty years. So why are these averages so far apart? There are several reasons for this huge difference in life expectancy.
Japan is the home of the koi fish and as such the breeders there have had a chance to greatly enhance the gene pool. Even when koi were first introduced to countries outside of Japan the highest quality koi did not leave Japan, this means Japanese koi are dramatically better than "domestic koi" (Next Day Koi does a great job explaining the difference between Japanese and domestic koi here). In order to compete with the quality of Japanese koi western breeders have breed koi to grow faster and this has led to a shortening of their lifespans over time.
In their eagerness to breed koi which can rival Japanese koi western breeders also often feed their koi an over-rich diet which leads to obesity and early death. Japanese breeders on the other hand often move their fish to large earth dams over the summer which allows them to forge and gain more weight and strength in a very natural way. This is not something the average koi parent can replicate but by avoiding overfeeding obesity can be avoided and your koi's lifespan can be increased.
Japanese winters are bitingly cold and as a result koi raised there spend more time wintering than koi in most western countries, and breeders rarely keep ponds warm enough to keep koi from going into their winter hibernation. In the west the desire for large koi often drives breeders to skip this hibernation period as koi do not gain much (if any) weight during it by warming their ponds to simulate summer temperatures. This hibernation greatly increases the a koi's lifespan, in fact being raised in a cold environment is one of the reasons Hanako (The worlds oldest koi fish) lived to a shocking 226 years of age.
The difference between a Japanese koi's lifespan and that of a "domestic" koi varies according to the type of koi fish as well. Newer types of koi, such as the Utsurimotno, are more similar while the most ancient varieties, such as the Kohaku, are very different depending on where they come from. However the koi lifespan really relies on how well the owner cares for it, if you feed your koi a properly balanced diet and ensure your pond is well cared for your fish will have a long and happy life no matter where it is from.
Were you surprised by how different Japanese koi and "domestic" koi are? I know I was! Another factor which I didn't talk about that probably affects the low lifespan of koi in western countries is our inexperience with raising koi. We have lost a lot of koi because of mistakes we made getting started as koi parents. If you want to know about the mistakes we have made and how to avoid them sign up for our survive and thrive mini course.