The Asagi is one of the oldest varieties of koi with its history going back over 165 years. The original Asagi magoi had blue-black coloring and scales with a net-like effect. Out of this koi developed two braches: konjo asagi, a darker blue, and the naruni asagi, a royal blue. It is from the konjo asagi that the modern Asagi evolved.
The upper half has net-like reticulated scale pattern of indigo, navy blue, or pale blue. The head should be clear and unblemished. Below the lateral line, the Asagi is a deep orange or red. If the red extends over the lateral line, the fish is called a hi Asagi.
In picking out an Asagi, the general rules is to pick one that is pale in color with the hi well below the lateral line. As time goes on, the blue will darken and the red will cover more of the fish. In hard water, the Asagi will probably darken to an undesirable color, so it is best in soft water ponds. There are several types of Asagi, so it is best to ask questions and be open to new and unusual things. The Asagi has a doitsu (German-scaled) version. The Shusui was one of the first doitsu varieties and it has a line of large, navy blue scales along the dorsal line and a bright orange or red belly. The dorsal line of scales, casually referred to as the "zipper," are the only scales on the fish and are to be in a straight, uninterrupted line. Since these are the only scales on the fish and are very visible, the "zipper" is an important factor in determining placement in koi shows. There are also several different unusual color types of Shusui.