Koi carp has been developed from the common carp in Japan in the 1820s. It has number of variants that has developed now by cross breeding with mirror carp and leather carp. Under ideal conditions, they may grow to 80-90 cm or more and may weigh around 10 kg. It is a peaceful fish but has the tendency of scouring the bottom, hence it should not be kept along with the aquatic plants. They are quiet hardy and can tolerate a temperature of 4-26 °C and pH 7.0-8.0. Omnivore and eat almost all type of food items from vegetable to worms and meat. It also readily accept all dry  and live fish foods. Sexes can be identified when female have large plump abdomen and male exuding white milt on pressing the belly. It is a prolific brooder and breeds two times in a year in Indian climatic conditions. Eggs sticky. It easily breed in captive conditions. Life span more than 20 years.