The Oscars probably just hit the maturity level. They go through a "sulking" period in which they won't really do much of anything; fighting, eating, moving, or even swimming. Once they are out of their sulking stage, if they still don't fight, they're definitely not mature enough yet. In time they will. No matter how many hiding spots you have, the Oscar always wants the territory the other Oscar has. Once they hit maturity, fights are almost a 24 hour thing. They usually don't fight until death, but it is a possibility. Since one is missing his lip, I would suggest taking him out and trying another Oscar. The one who tore his lip off will always present a problem for you though. Like an angry dog, an agressive Oscar can never be tamed enough to not fight at first sight. I would try two new Oscars and put the one with no lip in a tank by himself so he can recover.