He is a black wyandotte but the white/blue in the tail is a disqualification. The white could be from damaged feather follicles in the tail. When the bird molts, the feathers could come in black; you never know. If your blues do not have the problem with white in the tail, then the black should not have genetic problems with white/blue in the tail. I am thinking it is an environmental ( as in cell environment) problem an not a genetic problem. So I would say you have a self black bird.
Tim
Tim