Hellow Dick,
congratulations for your breeding activities, and thank you for posting the pictures. I'm very interesting in breeding, is fascinating watch the fry as they develop.
I'm trying to breed Sanke, got a spawn from a female and three males. All of them Sanke, well, one male is metallic Sanke.
Almost 50 % of the fry are fully black or black with either light yellow or orange head (some metallic) or dark colour, kinda chagoi.
From previous year spawn (same female, but unfortunately a yamabuki ogon male also contributed), I know almost for sure al these blacks or black with coloured head will not turn up Sanke. Mines are developing like some kind of karasugoi. Still have to check the only two of them that I keep from last year in an outdoor pond (if they have survived water snakes...)
Besides, this year I got fry (now ranging from 3 to 6 cm) that already show a developing Sanke coloration and pattern.
So your comment on selecting koi with yellow head and black body caught my interest. Maybe I'm wrong and culled just fry worth to keep? Could you post some pic of these young koi? Do you know when do they start changing that pattern to a Sanke-like pattern?
All the best,
Diego (Cordoba, Spain)