He doesn't really look like an oranda to me at the moment - that's an oranda in my avatar - but he might just be a baby at the moment and the head growth will come later. He might also be a she of course, you won't be able to tell that for some time either!
I've got a little fantail type thing that was sold to me as an oranda, he's only about 2cm long. I feed him on hikari oranda gold, I have no idea if it'll anything, but he does love it! They are floating pellets though, so just soak them for a bit and them squish them so they sink if you ever decide to feed them.