Koi Varieties - Shusui

A couple of weeks ago, we looked at the Asagi koi which is a grey-blue koi with reticulation in the scales and red colouration on the sides of the fish and on the fins. Today, we are going to look at the Doitsu version of this variety, the Shusui koi. To recap Asagi, check out our blog post here: https://www.kerutokoi.com/post/koi-varieties-asagi



Shusui koi from breeder Ikarashi Ozumi

Shusui (SHOO-soo-EE) koi are a grey-blue koi with a very striking red pattern along the sides of the fish and in the cheeks and fins. The Shusui koi also have no scales over their body except for a row of large scales along each side of the dorsal fin. These koi are very valuable to the history of koi as they started the scaleless variety of ornamental carp and, over the years, this scale-type has grown to over a hundred different varieties!



The Doitsu scale type originated in Germany when an Asagi koi was bred with a German Mirror Carp in the early 1900s. These Mirror Carp 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 koi from breeder Hirasawa

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, which is the scaleless version of a common 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.



Pongoi (Best Quality) Shusui Koi


When looking at a Shusui koi, it is difficult to imagine that it is just a scaleless Asagi. Without the reticulation in the scales, the pattern is almost unrecognisable. But the pattern is still the same – both koi have a blue base colour with dark blue scales (while a Shusui is ‘scaleless’, it still has one row of scales on each side of its dorsal fin) and a red pattern. Therefore, the Shusui should follow very similar rules to the Asagi koi.

Beni Shusui koi from breeder Aokiya

Firstly, the hi (red) pattern should be very prominent on the koi. Just like an Asagi, a Shusui should have a strong hi pattern on the side of the fish. The actual shapes of the pattern themselves are of less importance, the main thing is that there is a good amount of hi and it is positioned mostly along the side of the koi and in the cheeks. A Shusui should ideally not have any hi under its scales, only in the scaleless areas of skin. The hi itself should de a deep, vibrant red with a consistent shade across all of the hi and it should have crisp, clean edges between the hi and the blue-grey base colour.


Just like an Asagi, you should look at the head and the presence of any markings on the head. The best Shusui will have a clean head, meaning that there are no markings on the head at all. The head should have a consistent grey or a white colour all over and any of the hi pattern visible on the head would be regarded as an imperfection.


Finally, and this is where the Shusui differs from the Asagi, you should consider the quality of the Doitsu scale type. 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. You should look at each scale along the back and check that each scale is of similar size, either to all of the other scales or to its neighbouring scales, and no scale is out of place or damaged. 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.



Aya Wakaba

Aya Wakaba koi from breeder Aokiya

The Aya Wakaba (eye-EE-yah WAH-kah-BAH) is a new subvariety of the Shusui koi that was first shown in 2004 by the breeder Yamanaka Oya. It was created by breeding a Shusui with a Midorigoi (a Doitsu green or yellow single-coloured koi) which resulted in a Doitsu koi with the pattern of a Shusui but with a green coloured pattern instead of the hi pattern. Note that Aya Wakaba and Midorigoi are referred to as ‘green’ but they rarely actually look green and often look like a dirty yellow instead.


The name Aya Wakaba translates as ‘colourful young leaf’ and refers to the beginning of Autumn when the first leaves change colour before they fall. This name was given to the subvariety as a nod to the meaning of Shusui as well as referencing the main colour of their pattern being more yellow than the deep fiery red of a Shusui.




Shusui have incredibly striking markings, making them really stand out in any pond. It is this, along with their status as an original variety of koi and the first Doitsu variety, that makes them especially popular with many koi keepers, new and experienced.


Have a look here to see our current stock of Shusui koi:


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