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Koi Varieties - Doitsu Koi Carp

Welcome to our newest blog in the ‘Koi Varieties’ series where today we will be looking at Doitsu koi. Doitsu koi are a little different to other varieties of koi as the term refers to a type of scale on a koi rather than a specific colour and/or pattern.


Doitsu Showa from breeder Shinoda

Doitsu (DOYT-zoo) koi are also known as scaleless koi. Most koi have scales covering their whole body but Doitsu koi either have no scales at all or just have one or two lines of large scales going down the spine of the fish. Any koi variety can have Doitsu scales and when a koi has this scale type, the variety name is often preceded by the word Doitsu. For example, you could have Doitsu Kohaku, Doitsu Benigoi, or Doitsu Goshiki. You could even combine the Doitsu scale type with the Gin Rin scale type (see our blog post here for more information on Gin Rin koi: https://www.kerutokoi.com/post/koi-varieties-gin-rin-koi-carp) to produce Gin Rin Doitsu varieties! Some varieties, however, have a different name for the Doitsu version. For example, a Doitsu Asagi is called a Shusui and a Doitsu Matsukawabake is called a Kumonryu. But these cases are rare and most Doitsu koi use the Doitsu prefix!



When Doitsu koi first became popular, they were split into two categories which were Kagami (kah-GAH-mee) and Kawas (kah-WAH). Kagami was used to refer to Doitsu koi with multiple lines of scales on the back of the koi and down its lateral lines, whereas Kawas was used to refer to Doitsu koi without any scales or with just one line of scales on each side of the body along the base of the dorsal fins. Nowadays, the two categories are rarely used as most koi keepers deemed them unnecessary but some koi keepers and breeders still use the terms today.



Doitsu Kohaku from breeder Shinoda

The Doitsu scale type originated in Germany when an Asagi (a grey-blue koi with reticulation in the scales and red colouration on the sides of the fish and on the fins) was bred with a German Mirror Carp in the early 1900s. These Mirror Carp were very similar to the wild carp, also known as Common Carp, but they had a genetic mutation that resulted in certain growth genes not developing properly. This mutation was commonly seen in many types of carp including koi and zebrafish as well as thousands of other species and is visible in the form of a lack of scales or a fully scaleless fish. When the gene mutation was first spotted in Germany, the fisherman encouraged it and grew the population of fish with the mutation as it made preparing the fish for cooking and eating a lot easier and quicker. Eventually, many species developed to the point where every fish had the mutation.



After hearing about these scaleless fish in Germany, many other countries wanted them as they vastly reduced the work and time required to prepare meals and were therefore very valuable to the fish merchants and many other businessmen. One of these countries was Japan and once some of these varieties of carp, including the Mirror Carp, were imported into the country, fishermen quickly got to work introducing these new scaleless carp into their populations of carp to spread the gene mutation.


Shusui from breeder Aokiya

By this point, koi carp were already being bred as ornamental carp by breeders across the country and the Asagi koi was well-established. It was one such breeder, Kichigora Akiyama, who decided to breed an Asagi with one of these new Mirror Carp. Within only a few generations, a new variety of koi had been developed that looked like an Asagi but had the scaleless gene mutation to drastically reduce the number of scales on its body.


This new fish was originally called a Doitsu Asagi after the Japanese word for Germany, ‘Deutsche’, but the variety quickly developed and became less like the Asagi koi. As the Doitsu Asagi became more popular, it was renamed to Shusui which means ‘autumn water’ and refers to the pattern of red colour on a blue background looking like red leaves that have fallen from a tree to land in the river. The term Doitsu meaning scaleless koi stuck, however, and is still used today to refer to scaleless koi.



So, what should you look for when picking a Doitsu koi?


Doitsu Ki Kujaku from breeder Aokiya

Because a Doitsu fish has fewer scales than a Wagoi (non-Doitsu) koi, the scales that it does have are much more important. Any imperfection is immediately obvious and makes the whole fish look bad. Each scale should be looked at along the back and checked that each scale is of similar size, either to all of the other scales or to its neighbouring scales, and that no scale is out of place or damaged. It is often acceptable to have a large difference between the largest scale and the smallest scale as long as the size of the scales changes gradually along the spine of the fish. It is very difficult to breed for perfect scales so actually, many breeders aim for fewer scales rather than perfect scales as there is less chance for imperfections with a smaller number of scales!


The fish should have scales either along the lateral line of the body or down the spine of the fish, on either side of the dorsal fin. If the koi has any other scales elsewhere on the body or that are not in line then it will typically score very badly as these are considered to be big imperfections.



Aragoke Koi


Aragoke Kawarimono from breeder Okawa

Aragoke (ah-RAH-go-KEH) koi are a new subvariety of Doitsu koi that have much larger and irregular scales than the typical Doitsu koi. The scales on Aragoke koi have been produced from Doitsu koi for decades but koi breeders always eliminated these koi from their Pongoi koi as they were considered to be poor quality. Recently, however, Mr Ikarashi of Ikarashi koi farm challenged this idea and decided to grow on some of these fish rather than removing them. This resulted in the first Aragoke koi being shown to the public with mixed results. Some koi keepers loved them and some koi keepers disliked them but there was enough interest that more koi farms decided to also grow on their Aragoke and some more and more are appearing in koi keeper’s ponds.


The word ‘Ara’ comes from the Japanese word ‘Arai’ which means rough or crude and the word ‘Goke’ comes from the Japanese word ‘Uroko’ meaning scale. So, the name Aragoke literally translates as rough and uneven scales. Part of the appeal of this koi is the unevenness of the scales as well as their size so it is much less important than a regular Doitsu koi that the scales be neat and consistent – in many cases what makes a good Doitsu koi makes a bad Aragoke koi! You can view our current stock of Aragoke koi on our website here:


That concludes today’s article all about the beautiful Doitsu scale type. These can be truly stunning koi and a fantastic addition to any koi keeper's collection. Since almost every koi variety has a Doitsu version, there is a Doitsu koi for everyone! Take a look at our current stock of Doitsu koi here:


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