They will never sucessfully breed. I read a book that cichlids act like the other and breed to eat the fry. Its a evolutionary trait that they has develope.d over time. I'm gonna go look in my library and send you the book. I had this happen to me before with my auratus and redzebra. He stole the eggs possible from another fish in the same species.
I have had melachromis johanni breed with red zebra I have like 120 2inch to 3 inch fish.