While koi have only fairly recently (within the last few decades) gained widespread popularity among pond hobbyists in the US and UK, they’ve actually been around for thousands of years! Data collection has found that most modern koi breeding practices originated in China and Japan around the 4th century. In fact, mtDNA sequencing supports the commonly held belief that koi are descendants of the common carp (Cyprinus carpio). The sequencing found that the common carp originated in East Asia (an idea that was often argued), meaning this is technically the origin of koi, too!
Since the 4th century, the aquaculture industry has seen a huge boom in the number of breeds, patterns, and colorations of koi available. Actually, the DNA studies mentioned previously were also able to pinpoint that the large scale domestication of carp and subsequent breeding of them to obtain brightly colored varieties and unique patterns occurred in China beginning around 6,000 B.C.
These colorful, specially bred carp came to be known as “koi,” and were most often gifted to those with political and economic power as a gesture of good will and peace. This is how they initially made their way to Europe and, eventually, the Americas, becoming beloved pets rather than symbols of power and wealth.
Doitsu, or scaleless koi, are thought to have originated by accident due to a gene mutation hundreds of years ago. A lack of scales in fish is due to a genetic mutation that results in one of the two fibroblast growth factor receptor 1, or fgfr1, genes developing improperly. This causes partial or complete scale loss in fish, and has been seen not only in carp and koi, but in other wild fish such as zebrafish, as well. It should be noted that this particular mutation is most common on fish of the Teleost subclass, a group that evolved around 160 million years ago containing carp (including koi), zebrafish, and many thousands of other species. The Teleosts are currently the only known group of fish to contain the fgfr1 gene, which is seemingly why a lack of scales is more common in this fish group.
What Does Doitsu Mean?
As Doitsu koi were originally bred in Germany, “Doitsu” is the Japanese word for “German” or “Germany.”
In the early 1900, scaleless koi were selectively bred in Germany from scaleless or partially scaled German carp, sometimes called mirror carp, to serve as an easy food source, and were imported to Japan and other countries, as well. This eliminated the need to have to scale fish before cooking and eating them. Eventually, this unique trait caught on and became desirable in pet koi fish, now known as Doitsu!
Doitsu Varieties & How to Identify Them
Technically, any koi variety can be Doitsu, as any koi can naturally possess or be bred for the mutated fgfr1 gene. It should be noted that bred Doitsu koi do not always complete lack scales, but rather have a few scales arranged in a particular way. Doitsu with a line or lines of scales along their lateral line and back are called Kagami-goi, which translates to “mirror carp.” Doitsu that either completely lack scales or only have a single line of scales running along the dorsal fin on their back are called Kawas-goi, translating to “leather carp,” as you can feel their leathery skin. Below, we’ll cover some of the most coveted Doitsu varieties, as well as some of the lesser-known ones. All of these can be either Kagami-goi or Kawas-goi.
There are three primary Utsuri varieties. These are Ki Utsuri, Hi Utsuri, and Shiro Utsuri. Within these three primary varieties, other established variations can exist, such as Kin Gin Rin and Doitsu.
1) Doitsu Bekko
Bekko koi are characterized by their dalmation-like or “tortoiseshell” appearance, as they always have a base color topped with Sumi (black) spots or patches. They come in three color variations – a white base, known as Shiro; a red base, known as Aka; and a yellow base, known as Ki. Doitsu Bekko can be either Aka, Shiro, or Ki, as well as KinGinRin, and all varieties are fairly rare (with KinGinRin Doitsu Bekko being among some of the rarest koi out there!).
2) Doitsu Kawarimono
Kawarimono koi are non-metallic koi that don’t quite fit into any existing designated category of koi. There are currently 14 types of koi contained within this class, and all of them can be Doitsu: Kumonryu, Beni Kumonryu, Matsukawabakke, Beni Matsukawabakke, Chagoi, Soragoi, Ochiba Shigure, Karasu, Hajiro, Shiro Muji, Kigoi, Gold Crown, Midorigoi, and Kawarigoi. These koi are all incredibly unique – not fitting into other standard categories is a testament to that!
3) Doitsu Kin Gin Rin
Kin Gin Rin koi are metallic koi, with “Kin Rin” translating to “golden reflective scales,” and “Gin Rin” translating to “silver reflective scales.” As might be guessed, Doitsu Kin Gin Rin koi lack these reflective scales, but still possess shiny, metallic-looking skin, known as Hikari.
4) Doitsu Koromo
Koromos (sometimes called Goromo) were bred by pairing a male Kohaku with a female Asagi, resulting in most Koromo having red (hi) markings typical of a Kohaku with the slight indigo tint of an Asagi on the tips of its scales. Doitsu Koromo still possess this coloration despite lacking scales, and can be either Ai Koromo (red and white), Koromo Sanshoku (red and white with small black spots), Koromo Showa (red and white with large black spots), Budo Koromo (red and white with a purple-tinged “netting” appearance within the red portions, or any other color variation present in Koromo (there are many!).
5) Doitsu Kohaku
Kohaku koi are arguably the most popular and well-known koi breed, as they form the base for breeding many other koi varieties. Their simple, yet beautiful white base covered with red Hi markings can create over a dozen sub-varieties, all of which can be Doitsu. Doitsu Kohaku can often be richer in color than their scaled counterparts, as the lack of scales means that they don’t reflect light and therefore it’s easier to see their pigmentation.
6) Doitsu Kumonryu
Also known simply as Kumonryu, this is a variety specific only to Doitsu koi. It’s a highly coveted and interesting breed, possessing a white base with ink-black Sumi that can exist in thick, billowing patterns, cover the entire body except for the fins, or form as smaller (but still deeply black) spots. Kumonryu translates to “nine-crested dragon,” and references an old Chinese legend about the dragon Ryu, which could transform itself into clouds at-will.
This is a fitting name for this koi, as amazingly Kumonryu have very unstable coloration and can unexpectedly completely shift their patterning! Depending on water temperature, pH, age, diet, gender, stress, and overall health, Kumonryu can pretty abruptly (within just a few weeks) become all white, all black, or any combination in between. While any koi will naturally go through some color and pattern shifts as it ages, Kumonryu are the only koi known to do this so quickly and frequently.
7) Doitsu Ogon
One of the few Doitsu varieties to be able to be metallic, Doitsu Ogon, like scaled Ogon, are split into two categories – platinum and yamabuki. Platinum Ogon are a shiny, silver-white color, while yamabuki Ogon are warmer metallic shades like bronze, gold, or more yellow. If the koi isn’t shiny and metallic, it’s not an Ogon! Doitsu Ogon still possess this visual trait due to a trait known as Hikari, or shiny skin. Whether Doitsu or not, Ogon are known as some of the friendliest and most outgoing koi!
8) Doitsu Sanke
Sanke koi have distinct, porcelain-like white skin (called Shiro) with red to red-orange markings (Hi) atop it and some form of Sumi patterning. Sanke do not have any Sumi markings on the head; these would be considered Showa koi, not Sanke. As with the other koi on this list, Doitsu have the above characteristics but are entirely or almost entirely scaleless, giving their colors a more smooth and vibrant appearance. There are over a dozen variations of Sanke, and any of them can be Doitsu.
9) Doitsu Showa
Showa koi are the final of the “big three” varieties (along with Kohaku and Sanke) and were initially bred by combining a Kohaku with a Ki Utsuri, resulting in Showa koi with vivid red or orange, white, and black markings. Though similar to Sanke, Showa differ in that they have a black base, meaning that their black coloration can extend below their lateral line and onto their head. Sanke should not have Sumi in these regions. Like the other of the big three, Showa have over a dozen varieties and any of them can be Doitsu.
10) Doitsu Shusui
Shusui are the MVPs of Doitsu, as they were the first ever Doitsu koi variety! They are also one of only two koi varieties with blue coloration, along with the Asagi! Shusui were originally bred by crossbreeding a scaleless German carp with an Asagi; Shusui are therefore essentially just scaleless Asagi! Like Asagi, Shusui have distinct blue-grey patterning on their backs, red (Hi) running along their sides, and white (Shiro) that shows in-between.
11) Doitsu Utsurimono
Utsurimono koi, also known simply as Utsuri, have an inky black base that can be covered with one vibrant color that can be either yellow (Ki Utsuri), red (Hi Utsuri), or white (Shiro Utsuri). Their coloration tends to be very bold and bright, and all three types can be Doitsu.
How to Appreciate & Judge Doitsu Koi
If you’re considering entering your Doitsu koi into competitions, there are a number of things that you should familiarize yourself with. First and foremost, know that every competition is different and entirely dependent on the judges themselves – what may be considered appealing to one judge may not be to another. In Japan, judges also value fish based on their monetary value – a fish that costs more may result in an automatic bias in that fish’s favor, while if judged elsewhere patterning and proportions may come more into play. Try to know your audience beforehand.
General Guidelines for Judging Koi
The fish should not have any abnormalities, such as missing fins, misshapen mouth, or bruises (unless they were accidentally caused during transportation). Doitsu should also not have any parasites, ulcers, or other forms of illness.
Symmetry is also of great importance. The way that the Sumi are arranged from front to back and side to side should be balanced and fairly symmetrical (not strictly symmetrical). If present, patterns that are unique are also favored. The fish should also have a proportional, symmetrical head with proportional, symmetrical fins, and a torpedo-shaped body.
Doitsu Specific Judging Guidelines
As Doitsu don’t have many (if any) scales, the proportion and symmetry of the scales that are present is often judged fairly critically. The scales present should be present along either the lateral line of the fish or straight atop its back on either side of the dorsal fin (or both); if the Doitsu has random scales on its sides or belly, these are considered “out of place” and are judged negatively. The scales should ideally mirror one another on each side.
After checking the general guidelines, like symmetrical fins and a proportional body, and then checking on the symmetry and location of scales, judges will then move onto criteria specific to the scaled version of the Doitsu. For example, for a Doitsu Kohaku, the judge would then take into account Kohaku-specific criteria, such as its color balance and Hi symmetry, presence of Hi on the head, type of Hi patterning, and so on.
For a Doitsu Showa, the judges would move onto things like presence and type of Sumi pattern on the head (Menware and Hachiware are judged quite favorably), whether or not the white base has any yellow tinge to it, and how well their three colors flow about each other without interrupting or overpowering each other.
To learn more about judging criteria for specific koi varieties, check out our other koi guides here!
Keeping Doitsu – Health, Growth & Diet
1) Doitsu Water Quality
Doitsu koi can be particularly sensitive to things like parasites and sunburn as they lack protective scales. Additionally, brightly colored Doitsu, as with any more vibrant koi, will show some obvious signs if water quality is off. We say “obviously” because you will be able to visually tell by looking at your Doitsu if your parameters are off. For example, a diet too high in color enhancers, like spirulina, will cause any white portions on the Doitsu to take on more of a yellow tint. It can also cause off-color orange spotting in Doitsu with Hi coloration, such as Doitsu Kohaku. Water that has a higher KH (water hardness) and pH often results in Doitsu with darker, inkier-looking Sumi, though this can be a desired trait.
As mentioned above, Kumonryu in particular are sensitive to water quality and will change their coloration and entire patterning frequently throughout their lives based on shifts in water parameters and other things like diet or stress.
Like most koi, Doitsu needs are best met when the water temperature is 50° F to 78° F (10° C-25° C), pH is between 7.5 & 8.5, dissolved oxygen is above 7 parts per million (ppm), salinity is kept very low between .05 & .15 parts per trillion (ppt), and there are only 75 to 100 ppm of total dissolved solids (TTDS), such as metals, minerals, salts, and sulfates.
2) Price of Doitsu
Doitsu koi are a pretty mid-range koi as far as price goes. You can find young, smaller (under 8 inches long) Doitsu for $50 and below, while adults can easily be several hundred to over a thousand dollars depending on the exact variety. Doitsu KinGinRin tend to be among the most expensive due to their highly coveted, metallic appearance, while the big three (Kohakus, Showa, and Sanke) are usually on the more affordable side as they’re a bit easier to breed reliably. When purchasing, you should also factor in their water quality needs (discussed above) and the fact that proper aeration and filtration will be needed if these are not things already in place in your pond.
3) Doitsu Temperature
Though lacking solid scientific evidence to back this up, some argue that water temperature plays a role in the appearance of any Doitsu (or other koi). Apparently, colder water lends to darker red or yellow coloration, while warmer waters lend to less vibrant hues. This could be related to changes in fish metabolism as temperatures shift, and resultantly how they absorb nutrients that impact coloration. One theory is that colder water slows the metabolism, so those nutrients stay in the fish’s system longer even though feeding occurs less frequently.
As mentioned previously, Doitsu prefer water temperatures between 50° F to 78° F, or 10° C to 25° C. Additionally, make sure that your pond has varying depths to allow for your Doitsu, and any other koi, to swim to different depths to help naturally regulate their body temperature as needed.
4) Doitsu Diet
As Doitsu koi were bred directly from hardy German mirror carps (scaleless carps), Doitsu tend to have stronger immune systems as they weren’t bred solely from other koi or inbred. Nonetheless, a balanced diet is still essential to their health! To help develop and maintain healthy coloration, colorful Doitsu koi are often fed diets with color enhancers, such as those containing spirulina or krill, as well as those with ample (>30%) protein to aid in proper growth.
In particular, studies have found that feeds with high carotenoids result in a greater concentration of carotenoids in the skin, therefore leading to more vibrant coloring in yellow and red koi, such as Doitsu Sanke. If you have a Shusui, you may wish to amplify the blue coloration so it appears less grey or black – in this case, you’d utilize a food with supplemented astaxanthin, spirulina, and/or guanine, as these have been found to particularly amplify blue and purple coloration.
These color enhancers are of lesser importance if you don’t wish to show your fish at shows. Otherwise, though, the dietary needs of Doitsu are much the same as most other koi.
How to Breed Doitsu Koi
If you’re looking to breed your Doitsu for the purpose of obtaining a specific variety or scale type (scaleless or mirrored), do keep in mind that this can be tricky. Simply due to the nature of genetics, and the incredible amount of chance and nuance involved in coloration alone, make it very difficult to obtain exactly what you’re looking for with any koi breed, unless you’re a professional with an established line of Doitsu and are familiar with working with the fgfr1 genes.
Doitsu are among one of the easier koi types to breed. While it can be difficult to breed for a specific type (such as Doitsu Ogon or Doitsu KinGinRin), it’s not overly difficult to breed for koi without scales or with only some scales if you have two Doitsu parents.
What is the Cost of Doitsu & Where to Buy Them?
As mentioned previously, Doitsu are somewhere in the middle-ground of expense when it comes to koi varieties, though this does depend on the particular type of Doitsu. Juvenile Doitsu are generally quite affordable, usually below $50, while adult Doitsu, just as with any adult koi, will always be more pricey and generally around a couple of hundred dollars. More common Doitsu such as Doitsu Kohaku will tend to be on the lower end of the price range, while highly sought-after and more difficult to breed types like Doitsu KinGinRin can be several thousand dollars for an adult, and a few hundred for a juvenile.
As with any koi, these prices are quite variable and depend on the seller and location. We encourage you to check with your local breeder or a reputable online breeder for more exact information. Be sure to purchase Doitsu, or koi of any type for that matter, only from reputable breeders. A reputable breeder should display their credentials on their site. You can also determine whether or not a breeder is ethical and trustworthy by checking out koi forums – word of mouth travels fast, and koi owners are happy to provide info on both good and bad breeders.
Oftentimes, cheaper koi come from large fish farms or shady operations that don’t prioritize the health and wellbeing of the fish. Koi from non-reputable sources could be mistreated or have illnesses or parasites from being stocked with too many other fish or not being care for properly.
