National Koi Day – July 7, 2026

History of National Koi Day

Koi, or more precisely Nishikigoi, is a colorful variety of Amur carp, which is bred in open water from koi or water gardens for decorative purposes. There are many varieties of ornamental koi, which originated from the breeding that began in Niigata, Japan, in the early 19th century. The Japanese recognize several species with differing colors, patterns, and scales. Some basic colors are white, black, red, orange, yellow, blue, brown, and cream. Gosanke is the most popular category of koi.

Carp are a large group of fish that can be found in Central Europe and Asia. Different types of carp were first domesticated in East Asia and were used as food. Carp are cold-water fish, and their ability to survive and adapt to many climatic and aquatic conditions has allowed domesticated species to breed in many new locations, including Japan. Natural mutations in the color of these carp have occurred in all populations. In the texts of the Jin Dynasty, carp of different colors are mentioned. It was first bred for color mutation in China more than a thousand years ago, where selective breeding of colored varieties led to the development of goldfish.

Amur carp is a representative of a complex of species of the carp family native to East Asia. Amur carp was previously identified as a subspecies of common carp but has recently been considered a separate species called Cyprinus rubrofuscus. Since the fifth century B.C., Chinese people have been eating Amur carp.