excerpt from http://www.koi.com/
The Kumonryu is a Doitsu (German) koi that has a jet black pattern that emerges like billowing black clouds against a white background. The black pattern is variable and unstable, disappearing with changes in the water temperature, reappearing sometimes as a completely different pattern.
The name Kumonryu is derived from a legend that tells of a dragon (Ryu) transforming into a cloud and racing through the sky.
The Kumonryu is said to have been developed by breeding a Shusui with a Matsukawa Bakke.