I have 2 red devils in with one large oscar. The red devils own anything smaller than them in the tank. They leave the oscar alone, because of his size. I'm betting that once they get bigger they will kill the oscar. I had 2 parrots in the tank that use to chase the devil around. The devil grew just a tad and made the parrots life misserable. I just moved them to another tank 10 minutes ago...lol
