The origin of the name is almost as interesting as the koi itself. Sometime in the 19th century, as the story goes, a koi breeder who lived in a small village in a pine forest near a river found an interesting black patterned koi among his Asagi spawn. The strange thing about this koi was that the pattern seemed to change with the seasons. This koi quite logically came to be called a Matsu (pine) Kawa (river) Bake (changeable or variable).

Many of us have seen the scaleless (doitsu) version of this koi, called a Kumonryu, also known for its changing patterns, but we don’t often see Matsukawabake. This is unfortunate, as it is a historically important variety, contributing its genetics to the modern Showa. If you have ever purchased a young Showa, and raised it to an adult, you will attest to the sometimes frustrating, sometimes exciting habit of the sumi (black) pattern to go through many changes.

Recently we have seen some very nice examples of GinRin (shiny, reflective scales) Matsukawabake, reminding one of a clear night with its sparkling stars and white background of the Milky Way.

Genetically, Matsukawabake is a descendant of the Asagi Magoi line, which is the same line that lead to most white-based koi such as Kohaku and Sanke This seems somewhat contrary to logic, as we think of Matsukawabake, Kumonryu, Suminigashi, etc. as basically black koi, but one branch of the Asagi Magoi gene tree lead to a very dark colored Konjo Asagi, which lead to the black-reticulated Suminigashi, and thence to the Matsukawabake.

The reticulation is our best hint at this relationship to Asagi. Purchasing this variety can be an exercise in futility, as one has no idea of how it will turn out. This may also be one reason breeders don’t spend a whole lot of time breeding this variety.

This writer recently obtained, for a very cheap price, a one year old (tosai) black koi with white tips to the fins, commonly known as a Hajiro. In the sunlight, we could barely detect a faint pattern however, so we were interested in this fish and how it might develop. During its second year, more white began to appear. First on the nose, then the entire head and back onto the shoulder. The body changed from solid black to a black pattern with grayish-white areas with black edges on the scales. We now believe that this is a Matsukawabake – not at all what we thought we had purchased! We have also known of hobbyists who purchased a young Matsukawabake only to have it turn to an entirely black koi.

The lesson here is that if one wishes to have one of these curious koi, it might be best to try to purchase a two or three year old, which will have somewhat stabilized its coloration.