I don't think they would they just stay in the area of where their eggs are. They wouldn't chase the Oscar unless he went near the eggs. I keep a breeding pair in a 20 with 2 Africans and 3 Mayan cichlids and nobody ever gets hurt.
Wich ones are u saying that about cause I have a way over stocked at the moment 55 with about 30 cons a jack d a fire mouth and a silver dollar 2 mated pairs of cons with no aggression other than during mating and then only when they get to closes