Okayama Koraku-en koi pond

Koi, the colorful carp varieties of Japan, more specifically called nishiki-goi - "brocaded carp" - were selected through careful breeding from ordinary carps. Even today, after more than 200 years, if they are left to breed uncontrolled, they will return to the original grey color.

That's why in the koi ponds, among the vivid colored specimens, sometimes you may also spot a grey colored carp, like the one on the right side of this photo taken inside the Okayama Koraku-en.