National Koi Day Date in the current year: July 7, 2024

Koi are colored varieties of carp kept for ornamental purposes that originated in Japan. They are the domesticated form of the Amur carp, widespread in the fresh waters of East Asia from the Amur to Red River basins. It may be hard to believe, but these large fish are close relatives of the goldfish, kept by aquarium enthusiasts around the globe.

It is unclear when the Amur carp was introduced to Japan from China, but mentions of differently colored carp fish (red, blue, black, white, yellow) can be found in classical Japanese texts such as the Nihon Shoki (The Chronicles of Japan). However, it is believed that these unusual colors were the result of a mutation rather than selective breeding.

The systematic breeding of koi fish began in the 1820s in Niigata Prefecture, where Amur carp were originally farmed for food. At first, farmers bred red and white carp in addition to black carp, and then crossed them to produce red and white colored fish. After that, they further crossed them to create more different varieties. Colored koi became popular around the 1870s, and the first koi breeds were officially recognized in the early 20th century. Over the years, koi have become a poplar symbol of Japanese culture and aesthetics. In their native Japan, they are associated with good fortune, prosperity, luck, and perseverance in the face of adversity.

Today, there are more then a hundred koi varieties distinguished by coloration, patterning, and scalation; they are classified into 16 groups. The major koi varieties include Kōhaku (white with red markings), Showa (black with red and white markings), Sanke (white with red and black markings), Bekkō (red, white or yellow with black markings), Utsurimono (black with red, white or yellow markings in a zebra pattern), and others. Kōhaku, Showa and Sanke are collectively known as the Big Three (Gosanke). Koi are very hardy fish that are kept in outdoor ponds and aquatic gardens around the world, especially in the equatorial regions, where outdoor water gardens are common.

It is unclear who and when came up with the idea of celebrating National Koi Day, but the choice of the date makes sense. July 7 is the death anniversary of Hanako, a scarlet koi fish who is believed to have lived for more that two hundred years (the average Japanese koi’s lifespan is about 40-50 years, less for koi fish bred outside of Japan). Hanako’s age was determined by extensive analysis of her scales; she died on July 7, 1977 at 226 years old and is considered to be the longest-living koi fish ever recorded.

There are many ways to celebrate National Koi Day. You can learn interesting facts about koi fish and their symbolism in Japanese culture, visit a koi pond or koi farm near you, watch videos about koi fish on YouTube and TikTok, and post fish pictures on social media with the hashtag #NationalKoiDay to spread the word about the holiday.