Motoguro

Sumi at the base of pectoral fins. Seen primarily in Showa and Shiro Utsuri. It could mean Sumi in the tail fin but the term is rarely used for that. Small Sumi that is gathered together at the spot where the fins meets the body shows the quality of the Koi's Sumi. If the Sumi is spread as if by a broom it is a fault in Showa and Shiro Utsuri. high quality Motoguro makes the white pectoral fins appear dignified and is considered a highlight of these varieties.

(Courtesy of the excellent Book Kokugyo Vol II)