If they are already locking jaws make sure you keep an eye on them. Change up the decor in the tank every once in a while and it will reduce aggression. Also I have no experience with it but I have read a slightly lower temp like 76,77 seems to lower it a bit. When your oscars reach sexual maturity is when their aggression is going to start to peak I think around 7 - 8" or 7-8 months give or take.
55g - 3" Long-Finned Albino Oscar
10g - Heavily Planted, M GBR, 3 Otos, 6 Schooling Rummy's