Nishikigoi (or "koi") are a type of carp (Cyprinus carpio) bred and raised for ornamental purposes. The Nishikigoi is Japan's national fish. Although the multicoloured carp has been referenced in Chinese literature dating as far back as the Western Jin Dynasty (4th century, CE), it wasn't until the 19th century in Yamakoshi, Niigata Prefecture, that the Nishikigoi was commonly bred and raised. Varieties of nishikigoi are distinguished by their colour, pattern, and scales. The main colours include white, black, red, blue, green, yellow, purple, and cream. In addition, there are varieties in which the nishikigoi scales have a metal-like lustre to them, and these are referred to as "golden scaled", or "silver scaled".
Here are some varieties of Nishikigoi:
Kohaku - Red pattern on white skin base. The most popular variety.
Taisho Sanke - Red and black pattern on white skin base.
Showa Sanke - Red and white pattern on black skin base.
Asagi - Pale-blue scaled back and red belly.
In China, there is an ancient legend of "entering the dragon gate", whereby when a carp reached the top of a waterfall it turned into a dragon. This right-of-passage concept made its way to Japan in the Edo Period, and brought about the custom of decorating "carp-shaped streamers" to be hung outside on the "Children's Day Festival". Originally, the carp streamers were decorated to bring success and good fortune to the sons belonging to samurai class households, but since the abolishment of the class system in the Meiji Era, the tradition has become mainstream amongst all Japanese. Today, the custom of hanging carp streamers is practiced every Children's Day on the 5th of May.
It has long been said in Japan that eating koi is good for women's health. It is believed that eating pickled koi while pregnant leads to a healthy pregnancy and an easy delivery. In addition, eating carp is thought to produce healthy, nutrient-rich breast milk for new borns. These beliefs are common throughout all of Japan, regardless of location.
The Nishikigoi has a unique and flourishing existence in Japan, and seeing the care and attention paid in raising them is really someone can only witness for oneself. If you would like to visit the All Japan Combined Nishikigoi Show in Tokyo, below is a link to the website and tentative dates.