The sixth lesson in our Koi expertise course is about “Shiroji”.
I think the representative of Koi(Nishikigoi) that you often imagine is the variety called Kohaku. The red part of Kohaku is called “Beni” and the white part is called “Shiroji”. At first glance, “Shiroji” looks plain and plays a supporting role to accentuate the “Beni” and “Sumi”, but in fact, it is profound and is an important point to bring out the charm of Koi. In many cases, the “Shiroji” is considered more beautiful pure white with no other colors mixed in. The cleaner “Shiroji”, the more vivid the “Beni” stands out and enhances the beauty of the whole. “Shiroji” is more beautiful the younger the koi is, and it is the area that tends to turn yellow or become bloodshot as the Koi grows. Also, feeding the “Beni” to make the red color darker can stain “Shiroji, so careful care is essential to keep “Shiroji” clean. The feeding method, breeding environment, and genetic factors will also determine “Shiroji” characteristics of that Koi. Even if your Koi have a yellowish “Shiroji” when Koi are young, “Shiroji” can be cleaned up by tending it in the fountainhead. It is not uncommon for a young, yellow-headed Koi to have a thick “Shiroji” and a beautiful pure white “Shiroji” in the future. Also, Koi with thicker skin appear to have standing coverings. Such Koi have the potential to become thick and beautiful white Koi in the future.