Kigoi are koi with a solid, non-metallic yellow color. Kigoi differ from Yamabuki Ogon in that they have a flat, matte, non-metallic yellow coloration, where Yamabuki have a bright and metallic yellow.
Kigoi are sometimes referred to as "lemon koi" in the American koi industry. The most rare and sought after Kigoi, known as Akame Kigoi, have red eyes to go with the yellow body color. The red eyes give them a very eerie look.
Like all koi of a single color, the scalation and uninterrupted smoothness of the color itself is very important. Any missing or deformed scales, or any blemished scales of a different color than the rest, will detract greatly from the beauty of the koi.
Also, the head should be of a smooth and even color, with no blemishes or flaws.