I've assumed it was Chagoi, as it lightens up somewhat in a lighter background. Similar netting, dark, but no longer black, and from the side at least mine has a somewhat more wild carp (magoi) body shape. Came from the same spawn as the rest of our babies.
kuro is black, cha is tea.....I have seen many koi do this...a few years back i bred matsukawabake. I have a few babies still around..their colors are so transistional. All black some times, cha-goi looking, then pieces of white appearing...a friend of mine bought a ochiba that he called "coka-cola" that
did this very same routine. I think cause it's your koi jim you can call it what you want...just don't call it late for dinner! LOL
well the body and net pattern do remind me of chagoi but the head looks like a wild type carp? I think we will all have to wait until it gets bigger- much bigger?? JR