Asagi are fairly classical from a genealogical point of view, and constitute a very tasteful variety. They usually have blue on the entire back and Hi on the belly, pectoral fins and gill covers.
The scales on the back have whitish base and thus collectively give an appearance of meshes of a net.
The important viewing points are conspicuously vivid appearance of the meshes and light blue, spotless head region. However, as they age, black spots often appear in the head region and Hi on the belly tend to climb up reaching as far as the back.
Doitsu lineage does not mean Nishikigoi bred in Germany, but rather those Crossbred with Japanese Koi and black carp imported originally for food from Germany. They differ from ordinary Nishikigoi (or "'Wagoi' meaning Japanese Koi) in scale arrangement.
Doitsu Koi with lines of scales on the back and along the lateral lines are called "Kagami-goi (mirror carp)," and those without scales or with only one line of scales on each side along the base of the dorsal fin, "Kawas-goi (leather carp?)."
Doitsu Koi are crossbred into almost all varieties of Nishikigoi. Doitsu Koi are to be viewed for the orderliness of scale arrangement and the absence of unnecessary scales. Each Koi should have the features characteristic of its own original variety, of course.
This category includes all Koi with shiny body but devoid of any markings. Hikari-muji are divided into "Yamabuki Ogon (with pure yellow, metallic sheen on the entire body)," "Platinum Ogon (with shining platinum color)," "Orange Ogon (with orange sheen)," "Kin Matsuba (literally 'golden pine needles,' for individual, glittering scales appearing like raised markings)", and "Gin Matsuba (literally 'silvery pine needles,' for glittering scales on the platinum ground which look like raised markings)," etc.
As they don't have any markings, the condition of luster and body conformation become the essential points for appreciation of Hikari-muji group. Excellent luster is the one which covers the whole body evenly.
Hikari utsuri are Koi of Showa Utsurimono group (Showa Sanshoku, Shiro Utsuri, and Hi Utsuri, etc.) displaying "Hikari (luster or glitter)," and include "Kin Showa (with lustrous gold color)," "Gin Shiro Utsuri (with platinum sheen)," and "Kin Ki Utsuri (literally 'golden yellow Utsuri')."
The point of appreciating this group is of course the intensity of the Hikari, the very characteristic of the Hikarimono group.
Their markings are similar to those of Showa Sanshoku and Utsurimono group mentioned before. The tone of gold and Sumi is deeper, the better. However, there is an intricate aspect which we have to pay close attention. Both Hikari and Sumi pigment have a tendency to cancel each other -- most Koi with strong Hikari have deep Sumi. Consequently, Koi having strong Hikari and firm Sumi at the same time are very rare.
The Kohaku is the most popular variety of Nishikigoi. So much so that there is an expression, "Koi avocation begins and ends with Kohaku." There are various tones of "red" color - red with thick crimson, light red, highly homogeneous red, blurred red, and so on.
There are all sorts of "Kiwa (the edge of the pattern)" -scale-wide Kiwa, razor-sharp Kiwa, and Kiwa resembling the edge of a torn blanket, etc.
Shades of white ground (skin) are quite diversified too -- skin with soft shade of fresh-unshelled, hardboiled egg, skin with hard shade of porcelain, yellowish skin, and so forth.
Whereas Kohaku and Taisho Sanshoku have red and/ or black markings on the white ground, Showa Sanshoku have red markings on white patterns formed on the black background. We have discerned such different arrangement by observing the processes of fry development.
Kohaku and Taisho Sanshoku are almost completely white when freshly hatched. Young fry of Showa varieties (including Showa Sanshoku, Shiro Utsuri and Hi Utsuri, etc.), on the other hand, are almost completely black when just emerged from eggs.
As days go by, white patterns become visible against the black background, and red markings will soon appear on the white patterns. We should, therefore, say that Showa Sanshoku have black texture.
Shusui have been crossbred between Doitsu Koi and Asagi, and their points for appreciation, therefore, are basically the same as those for Asagi.
Shusui also have the tendency to show black spots in the head region as they grow big. Koi with spotless head region are valued highly, of course.
The arrangement of scales is also important. It is desirable that scales are visible only the back and the regions of lateral lines -- no undesirable scales in any other place. Hi on the belly covering over the lateral lines are showy.
Koi with a red head patch are called "Tancho." Most common are "Tancho Kohaku (all-white Koi with Tancho)," "Tancho Sanshoku (white Koi with Sumi similar to Shiro Bekko, and with Tancho)," and "Tancho Showa (Showa Sanshoku without red markings except for Tancho)," etc. However, "Tancho Goshiki (Koi of five colors with Tancho)," and "Tancho Hariwake" are rare.
Tancho do not form a single, independent kind of Nishikigoi; they all can be bred from Kohaku, Taisho Sankshoku or Showa Sanshoku. Their red patch happen to show up only in the head region. Tancho, therefore, can not be produced in bulk even if you so wish.
The essential point for appreciation is the red patch in the head region, of course. The red head patch sitting right at the center of the head region is the best. The white skin is also important as it is the milky white color that sets the red head patch off to advantage. The Sumi of Tancho Sanshoku and Tancho Showa are the same as Bekko and Shiro Utsuri respectively.