Carp are coldwater fish, and their ability to survive and adapt to many climates and water conditions allowed the domesticated species to be propagated to many new locations, including Japan. Natural color mutations of these carp would have occurred across all populations. Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. While the possible colors are virtually limitless, breeders have identified and named a number of specific categories.