Koi

Japan has a strong tradition of keeping and breeding koi, and in the late 20th century these ornamental fishes became popular in many other parts of the world as well, including Europe and North America.

A wide range of koi varieties exist, which differ from each other when it comes to external features such as colours, patterns and scalation. Examples of common koi colours are white, cream, red, orange, yellow, blue, brown, and black.

Koi grow fairly big and are commonly kept in garden ponds, but can be kept in aquariums too if the tank is large enough. Since they are bred chiefly for ponds, they tend to look especially striking when seen from above, and this is also how they are normally depicted in Japanese art.

2 koi

Koi are not only beautiful to look at, they can also help reduce the numbers of water-borne insects – including mosquito larvae – in garden ponds and other waterways. For this reason, they have become a popular addition to “water hazards” on golf courses in suitable climates.

The formal name for these fishes in Japanese are nishikigoi (錦鯉), which means brocaded carp. Their wild ancestor is the Amur carp (Cyprinus robrofcuscus), although some variants of koi also contain genetic material from another closely related carp species.

If you use only the word “koi” in Japan (instead of saying nishikigoi), be aware that it denotes any type of carp – including the ones in the food market.

In Japanese culture, the nishikigoi has become a powerful symbol of luck, fortune, prosperity, and perseverance in the face of adversity. It is also worth knowing that in Japanese, “koi” (which means carp) sounds just like another word which means affection/love, which has helped the nishikigoi become a symbol for love and affection in Japan.

Japan is the main producer of koi, both for the domestic market and for export. In 2016, Japan exported 295 tonnes of koi fish. The Niigata Prefecture is the epicentre for koi, and koi has been bred here since the early 1800s. This prefecture, named after its largest city, is located in Japan´s Chūbu region on the island Honshu.

Classification

As mentioned above, the wild ancestor of koi is the Amur carp (Cyprinus rubrofuscus), although some variants of koi also contain genetic material from another closely related carp species.

Koi did not develop in the wild and is not classified as a subspecies of C. rubrofuscus. In scientific literature, koi is sometimes referred to as Cyprinus rubrofuscus var. “koi”.

Scientific classification of the Amur carp

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cypriniformes
  • Family: Cyprinidae
  • Genus: Cyprinus
  • Species: Cyprinus rubrofuscus

Is koi and goldfish the same?

No. They both hail from carps, but koi was developed from wild members of the genus Cyprinus in Japan and the goldfish from wild members of the genus Carassius in China.

Also, the tradition of keeping goldfish is much older. The earliest recorded instances of Cyprinus carp mutants being red, orange or yellow are from the Jin dynasty (266-420 CE), and by the Song dynasty (960-1279 CE) the selective domestic breeding of goldfish was firmly established in the empire. From China, goldfish keeping was introduced to Japan from China as early as the 1500s. Koi breeding, on the other hand, did not commence until the 19th or possibly 18th century.

Important: It is well known that certain species of carp can interbreed with each other, and goldfish and koi are not genetically dissimilar enough to prevent interbreeding if they are kept together. You can however expect the offspring of goldfish x koi to be infertile.

The name nishikigoi

The beautiful colours and patterns of koi has been likened to exclusive brocade fabrics, and term nishikigoi is derived from two Japanese words: nishiki 錦(brocade) and 鯉koi (carp).

When they are combined to form one word, the “k” sound in koi changes to a “g”.

The pronunciation of nishikigoi is approximately nee-shee-kee-goy.

Earlier, colourful ornamental carps where known in Japanese as either irokoi (色鯉) which means coloured carp, hanakoi (花鯉) which means floral carp, or moyōkoi (模様鯉) which means patterned carp.

Exactly how nishikigoi and koi became the favoured terms remain unclear. According to one story, the terms irokoi and hanakoi fell out of use in Japan during World War II because they could have a sexual meaning and was considered improper. According to another theory, nishikigoi was originally only used for the Taisho Sanhoku variety of koi. Since this version became so popular, the name nishikigoi eventually became a catch-all for koi.

koi spawn in shallow water

Investment Grade Koi

High-quality koi carp can fetch a very high price and there are a large community of people who choose to invest in high-quality carp in the same way most people invest in stocks, cryptocurrencies or CFD certificates.  Some investors in High-quality koi in the hope of producing high-quality offspring while other invest in young high-quality koi carp in the hope that they will continue to develop well as they grow older. If they do they can fetch a lot higher price in a few years. Investing in young carp to grow them out is similar to investing in the stock market in that it requires a lot of skill and a little bit of luck to be successful.   Buying a high-quality koi to produce high-quality offspring is more speculative since most fry produced by high-quality fish will be of lower quality. Only one fry in a hundred thousand will become a high-quality investment koi. A few thousand might become high-quality hobbyist fish while most fish will be of lower quality. The total return on a spawn can still be high since a single female can lay a very large number of eggs. The odds pf

Lifespan

When a koi named Hanako died in Japan in 1977, it was well over 220 years old. Her age had been determined earlier by two studies of the growth rings of one of its scales. In 1966, her age was announced to be 215 years. This report also notes that she measures 70 cm in length and weighs 7.5 kg.

The long-lived Hanako was an anomaly, but properly cared for koi can definitely attain an age of 50-100 years.

Ferral koi

When koi is released into the wild, they tend to revert back to the natural colouration of Amur carp in a few generations.

Koi are adaptable and can survive in many different parts of the world. In some places, ferral koi are considered a problematic invasive animal. One example of such as place is Australia.

The natural behaviour of Amur carp, and koi, is to stir up the substrate where they live. This can greatly increase the turbidity of the water, and also be a problem for aquatic plants that grow rooted in the sediment.

Types of Koi

Here are some of the most common types of koi:

  1. Kohaku: This is one of the most popular types of koi and is known for its simple red and white colour pattern. The white is typically pure, while the red has a slight orange tint.
  2. Sanke: This type of koi is similar to Kohaku but has the addition of black markings. Sanke have a white base with red and black markings.
  3. Showa: This type of koi has a black base with white and red markings. Showa has a more complex colour pattern than Kohaku and Sanke.
  4. Utsuri: Utsuri have a black base with white, red, or yellow markings. The markings are often bold and striking.
  5. Bekko: Bekko has a white, red, or yellow base with black markings. The black markings are typically arranged in a pattern that resembles a net.
  6. Asagi: Asagi have a blue-grey colour on their back and a red or orange colour on their belly. They also have scales with a silver or white outline.
  7. Shusui: Shusui have a blue-grey colour on their back and a red or orange colour on their belly, similar to Asagi. However, Shusui has a line of scales along their back that have a metallic silver or gold colour.
  8. Ogon: Ogon have a metallic, single-coloured body that can be gold, silver, or platinum. Ogon has a simple, elegant beauty that is highly prized in the koi world.

Ghost koi

The Ghost Koi, often hailed for its unique appearance, is a hybrid fish that combines the traditional Japanese Koi and wild carp. Its name derives from its distinctive metallic, shimmering scales and a more translucent, ghost-like quality than its colourful counterparts.

Ghost Kois usually feature a solid, silvery body combined with patches of color, often orange or gold, primarily on their head. This intriguing blend gives them an ethereal, almost mystical appearance, setting them apart in any pond.

Ghost koi are known to sometimes be aggressive and are known to kill goldfish and koi. It is therefore best to not keep them with true kois or goldfish.