Agreed with dirty redd...male ZZ RD with a hard kok.
Your FH may develop pearls on his kok as he gets older...mine didn't get them till he was a year old.
IMO, kok growth is dependant on 3 things and in that order:
1) genetics
2) diet
3) water quality
I give your fish a 6. With the proper care, he could turn out to be quite a looker!