Koi is an ornamental variety of common carp, Cyprinus carpio. They have stout and elongated bodies, and their fins are short but full of colours. They have distinctive and colourful body patches those make Koi fish attractive. Usually, Koi fish are preferred in outdoor ponds or water gardens. They have a range of colours including white, black, red, yellow, blue, and cream. The special feature about Koi fish is that they do not have varying body shapes across their breeds, but coloration and scalation could be different among them. Koi fish has two small whisker-like sensory organs hanging in their mouth known as barbels. Japanese started to breed Koi as an ornamental fish in the early 19th century from a common carp. (source:ww.differencebetween.com)