Koi is an informal name for the colored variants of the European common carp. There are many varieties of ornamental koi, originating from breeding that began in Japan in the early 19th century. Several varieties are recognized in Japan, distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, yellow, blue, brown and cream. They can grow very large, so plan to move them to a pond and they will thrive for many decades.