Watching fry' growth is fun and interesting, isn't it? Once we grow them to tosai size, say 4-6 inches, usually we would be convinced that having good ones is very difficult since Marjory offspring are unacceptable as nishikigoi by its coloration and pattern.
Nobody else but your fry themselves are the best teachers for you......
however generally speaking, the plain brown colored ones, chagoi/soragoi/magoi group, won't change color and pattern. and also the plain orange ones, akamuji/higoi group, would most likely maintain that way in future.
it is said that if plain orange one have white belly, some of them might have a chance to making pattern later.... a little chance though. the plain white ones at this stage would also maintain like that.
then the three colored ones of this variety, Sanke, will change its appearance by reducing (tighten) amount of black (sumi). sometimes yellow/orange pattern are hiding under large patch black (sumi ) on body at this stage.
Lastly, I saw a couple of Blue color fry in the pictures, regular and Doitu scale, that I have never seen.... so, they are out of my imagination....interesting!!