Good morning Mitch. You, as a marine fish guy would probably be most comfortable with scientific names. And I'm sure you cringe when you enter a fish store and see things like 'lollypop percula' on the tank price listing!
Koi have both descriptive names and artistic/poetic names. But they also have commercial names.
The evolution of kumonryu is a long story for another time, but basically the name was liberally applied to almost any fish that arose from a crossed of karasu goi types and doitsu fish and was black and white . Then red was added ( doitsu kohakus are the lastest addition). These are all NON metallic fish to this point. And then it was made metallic and gave rise to kokuryu clan and the wheels really came off the bus from there! The latest 'wandering off the reservation came in the form of a kinda metallic showa/goshiki/kujaku!! - it was pure kawarimomo. But since a few did very well in koi shows, a new trade name was needed and so Benikoki was born---
JR