Congrats on the successful spawn firstly! What strain is the pair? You didn't mention how old the fry are. Sounds like the male's slime coat is getting depleted to the point where it hurts to have the fry grazing on him continually. Are you feeding the fry as yet? If so, with what & how often?
If his aggressive behaviour is purely parental instinct you may consider covering the back & sides of the tank to decrease stimulation from the outside world.
If you are concerned for the safety of your fry you might consider removing the male back to the tank he came from.