Koi or Nishikigoi is the colored variety of the common carp (Cyprinus Carpio), which can be supplied in many different colors by selective crossbreeding.

Koi are originally from Asia where they served as food for the people and were brought to Japan about 1000 years ago via China and Korea.

It was not until the 19th century that the first koi as we know it were bred by Japanese growers.
Nowadays Niigata Prefecture is the center of the koi industry.

 

In the spring the parents are put together to take care of offspring. This used to be done in small outdoor ponds, nowadays selected parent animals are put together in indoor pools.
When the small koi (± 12 mm) can swim, they are brought to the outdoor ponds for growth. These ponds contain a lot of natural food, which benefits the growth and physiques of the koi.

In the autumn the koi are selected and taken to indoor pools for sale and / or hibernate.
Overwintering koi that are not for sale are kept heated and receive sufficient food to grow. Small koi for sale are not kept in heated basins and are not fed.

Most koi that come to Europe are Tosai (1 year old), Nisai (2 years old) and Sansai (3 years old).
In the spring, the tosai will be sent to Europe by plane. This is done in plastic bags with enough oxygen for the long journey (30-40 hours).
At the importer the koi stay in quarantine for several weeks.  After the quarantine period the koi are sold to traders and garden centers, where the koi are for sale for private people.