Koi (Japanese: 鯉, Romaji: koi) or more specifically nishikigoi (錦鯉, literally "brocaded carp"), are ornamental varieties of common carp (Cyprinus carpio) that are kept for decorative purposes in outdoor koi ponds or water gardens.
C. c. haematopterus
|Cyprinus carpio haematopterus|
Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream.