Language of Koi: 
The Shiny, Hikari Muji Varieties

Published on September 1, 2016

Koi are often called "living jewels." The shimmering, metallic skin on this koi exhibits excellent luster — similar to precious gold.
Koi are often called “living jewels.” The shimmering, metallic skin on this koi exhibits excellent luster — similar to precious gold.

I’ve heard from some koi retailers that the shiny koi, or Hikari varieties, are usually the first to sell from their fish retail tanks. The shimmering beauty of all Hikari koi, whether single or multicolored, is eye-catching and very much admired by their customers. It’s the shiny metallic skin and flashy pectoral fins that make these types of koi very popular with pond owners and koi enthusiasts. In this first installment of a series for POND Trade, you will learn about the characteristics of the Hikari varieties and how to distinguish them from their nonmetallic equivalents. You’ll also learn what to look for when evaluating the Hikari types.

There are three classes of Hikari Koi: Hikari Muji, Hikari Utsuri and Hikari Moyo. We’ll focus on just one class, Hikari Muji, in this initial installment.

Metallic Skin with Luster

All Hikari koi varieties, regardless of class, have skin that is metallic. Shimmery, metallic skin with luster is their common characteristic and the unique trait that groups them together. The Japanese word hikari means “shining,” so it makes sense that all koi in the Hikari classes have shiny, metallic skin with luster. However, do not confuse metallic skin with shiny ginrin scales, which is an entirely separate classification.

Aqua UV
 Strong luster, or sheen, is highly desirable on the skin of Hikari varieties. The term “luster” refers to the light-reflecting quality of the skin. Luster should cover the entire koi, apparent from the tip of the nose to the tip of the tail, and all the way through the fins. The metallic skin should shine like polished gun metal. The quality and consistency of the luster is highly scrutinized at koi shows. An easy way to understand luster is to visualize a piece of satin fabric. Satin is bright and iridescent, appearing thick with a heavy sheen, regardless of color. By comparing this satin fabric to a plain cotton material, its luster becomes obvious. Or, just compare plain glass beads to a strand of pearls. Both will be shiny, but the pearls will have a thick, iridescent quality. This is the essence of luster.

There are clues to help identify koi of the Hikari types. Learning to recognize iridescent metallic skin is your first step. Thoroughly examine your koi and evaluate its skin for a metallic sheen. Does its skin have iridescence, or the attractive and distinctive feature known as luster? Look at the head and face for the presence of luster or shimmer. Now look at the pectoral fins. Do they appear heavy and thick with color and shine, or are they slightly transparent? Next, study the scales to determine if they are covered with pearl-like skin. Focusing on these areas for the presence of sheen will help differentiate metallic from nonmetallic skin types. Remember that all Hikari koi varieties have shiny, metallic skin, from nose to tail.

Fins and Scales

Hikari variety
Hikari variety.

Just like many of the other koi varieties, the Hikari types are bred with elongated, flowing fins, or butterfly fins — though sometimes they are hard to find. The fins on Hikari varieties, whether traditional or butterfly, should have a thick and lustrous appearance. This characteristic is attributed to the radiance of its metallic skin and is quite a contrast to nonmetallic fins, which are often transparent on young koi. The prominent and showy pectoral fins on Hikari varieties contribute to their popularity.

Most of the koi in the three Hikari classes are wagoi, which means that their bodies are totally covered with scales. Hikari types may also be found with Doitsu scales. Doitsu is the term used to describe koi with German heritage, which have scales present only along the spine and occasionally along the lateral line. In fact, a few Hikari varieties, such as Kikusui, are always of the Doitsu type.

Ginrin, or kin-gin-rin, refers to highly reflective, sparkly scales, or diamond scales, and is sometimes incorrectly referred to as metallic. Ginrin is a scale variation and not the same as metallic skin. These are two completely different characteristics and are sometimes hard for a novice to differentiate. The light-reflective, sparkly effect of ginrin is reminiscent of tin foil and is only evident on the scales, not on the koi’s head or fins. Iridescent metallic skin, on the other hand, is evident in all these locations. To add to the confusion, Hikari koi may also sometimes have ginrin scales.

After you’ve determined the Hikari type of koi, you’ll evaluate the colors and pattern — or lack of pattern — to properly identify the right Hikari class for your koi. Many koi varieties fall into each of the three Hikari classes. Being able to name them correctly can be a challenge. Some are easy to recognize, and some take a little more time and effort to identify. The age and lineage, as well as the stage of pigment and pattern development, are all factors to consider for accurate identification. Often the lines become blurred between one type and another, but with practice, you will be able to name each one.

The Hikari Muji Class

The first class to study is the Hikari Muji, or Hikari Mono group. The koi in this class are single-colored, metallic fish, and most are Ogon. In Japanese, muji (or mono) means one, referring to the fact that each is a single-colored fish, devoid of a pattern or markings. Since there are neither patterns nor multiple colors to evaluate, the qualities of luster and color are paramount.

Luster on the Ogon’s skin is of utmost importance. The luster should extend completely over the body and fins. This shimmery sheen will make your Ogon visible even in water of less-than-desired clarity. A strong luster is preferred, so evaluate the entire fish — even its fins — for the presence of luster. As the Ogon lack accompanying markings or patterns, the condition of its skin luster and the body conformation become essential points of appreciation. Excellent luster is that which evenly covers the entire body. Additionally, a full, voluminous body is desired. Generally, koi of the Hikari Muji group quickly become accustomed to humans and can easily be trained to accept food from an owner’s hand. With a hearty appetite, the Ogon can rapidly grow to a large size.


Gin Matsuba
Sumi on the scales of Gin Matsuba, known as
reticulation, are often referred to as pinecone
scales. Notice the clean, iridescent, platinum
color on the base, with prominent luster.

Color is another major characteristic to consider. It should be solid and consistent from the nose to the tail, with no variance. When color is rich and constant, it is often referred to as deep, or thick. The intense and vibrant skin color on Hikari Muji varieties propel them to the top of the list for many hobbyists.

Generally, colored pigments are distorted or transformed slightly on the luxurious, metallic base of Hikari koi. Yellow tends to become a rich, golden color, and white will tend to have a glistening, silver hue. Choose a koi with good, consistent coloration overall, without blemishes from a concentration or lack of pigment.

There are many koi of one color in this class. The majority happens to be Ogon. Remember that every fish in the Hikari Muji class is a single-colored, metallic-skinned koi.

Popular varieties of koi in the Hikari Muji class include:

• Yamabuki Ogon — A yellow-colored, metallic koi
• Platinum Ogon — A white-colored, metallic koi
• Orengi Ogon — An orange-colored, metallic koi
• Hi Ogon — A red-colored, metallic koi
• Nezu Ogon — A gray-brown-colored, metallic koi

The head and body should be clear of blemishes and random pigment spots. The fins should be the same color as the body. Some Ogon have white-tipped fins, which is perfectly acceptable.

Matsuba Varieties

Matsuba varieties are single-colored, metallic koi, just like the Ogon. However, they have isolated sumi on the center of each scale. This feature is called reticulation and is generally referred to as pinecone scales. The addition of sumi on the scales atop a solid-colored, metallic ground does not eliminate them from the Hikari Muji class; the dark centers are not considered a pattern, so in this class they remain. Kin Matsuba (gold) and Gin Matsuba (silver) are still considered to be single-colored, metallic koi.

The same guidelines for depth and clarity of color that apply to the Ogon also apply to Matsuba. Luster is also expected on the metallic Matsuba. The sheen should cover the entire fish, including the fins, producing a smooth, polished appearance.

Use the tips you’ve learned in this article to evaluate a koi’s color and skin type to properly identify its class and variety. Again, if your koi is single-colored and has metallic skin with iridescence or luster, you may conclude that it belongs in the Hikari Muji class.
In the next issue, we will discuss the Hikari Utsuri and Hikari Moyo classes. Also, be sure to check out illustrations of these and many other koi varieties on the Kloubec Koi Farm website.

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