Koi is a type of fish that includes the Amur carp (Cyprinus rubrofuscus) which has attractive and tame ornaments. Often this fish is considered a variant of the goldfish (Cyprinus carpio) even though both are genetically different. Koi are usually kept as decoration for the purpose of beauty and good luck indoors and outdoors (koi ponds or water gardens, because koi fish are believed to bring good luck