Not a pic but a graphiic.
www.koi-clubs.com/SouthEast/HOT/Hotspot10.pdf
You'll find my take on this subject on page 9. As you'll see it was
something I was taught very early on in the hobby and almost
forgotten until the subject was rekindled recently.
However, like a lot koi-related issues, I resorted to earlier publishings
of JR for supporting evidence.
rgds
Bern