system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can it be that koi fish live an average of 15 years outside of Japan, 40 years in Japan, but the oldest koi fish lived to be 226 years old?
gpt
I'd venture that the lifespan of the Koi depends largely on how they're cared for and the knowledge of their caretaker rather than on the location alone. The Japanese often being anal about all things traditionally Japanese, they probably have very strict protocols that the casual Koi owner doesn't or can't follow. This would explain the discrepancy, as well as the climate of where they're raised.

As to how a Koi reached 226 years old, it's likely a one-time (or very rare) instance and not a normal lifespan. Every species of animal or fish, including humans, has specimens that will live far longer than normal. This can be explained by chance, diet, living conditions, and genetics.