Today Koi are bred in every country and considered to be the most popular fresh-water ornamental pond fish and are often referred to as being "living jewels" or "swimming flowers".
Koi are a variety of the common carp, Cyprinus carpio. Carp fossils have been discovered in South China dating back about 20 million years. Some varieties are known for their hardiness, which records claim can live for long periods of time if simply wrapped in wet moss continuously kept damp.
Some authorities believe Koi originated in Persia and spread throughout the ancient world.
Koi, or nishikigoi - Japanese for "brocaded" carp - were first described in writing from a Chinese book written during the Western Chin Dynasty, 265-316 A.D. At that time they were described as white, red, black and blue.
What happened to Koi from the 2nd to the 17th century is still being investigated, but many suspect Koi were gradually spread around the orient, and possibly even via trade caravans to or from the middle east.
Koi breeding in Japan is recorded from the 17th century in the rice-growing region of the Niigata Prefecture. They were originally bred as protein food supplements.