Koi are a domestic variety of the common carp, Cyprinus carpio that have been bred to display desired physical and behavioral characteristics. Koi keeping and breeding became popular among Japanese farmers in the 19th century. Selective breeding has led to a wide variety of colors and combinations, the most popular of which are a mixture of white, orange and black.
Koi as Pets
Many hobbyists keep koi in aquariums and outdoor (in appropriate climates) or indoor ponds. Naturally omnivorous, koi will eat most vegetables and commercially prepared flake or pellet food. Koi appear to recognize their food providers and will congregate at feeding time. Many koi owners have trained their pets to take food directly from their hand.