koi carp i tattooed on a friend
Carp are known as koi in Japan. Of the various domesticated carp species, the common carp (Cyprinus carpio) is one of the more commonly used in aquaculture. The common carp was aquacultured as a food fish as at least as far back as the 5th century in China.[5] Common carp were first bred for color in Japan in the 1820s, initially in the town of Ojiya in the Niigata prefecture on the north eastern coast of Honshu island. By the 20th century, a number of color patterns had been established, most notably the red-and-white Kohaku. The outside world was not aware of the development of color variations in koi until 1914, when the Niigata koi were exhibited in the annual exposition in Tokyo. At that point, interest in koi exploded throughout Japan. The hobby of keeping koi eventually spread worldwide. Koi are now commonly sold in most pet stores, with higher-quality fish available from specialist dealers.[