Right now they're in the same 55 gallon tank with a bunch of other things (cichlids, sharks, goldfish, etc), but I just bought another 55 gallon for the oscar.. and looking into getting something for the convicts for when they grow up too (convicts are about an inch long right now, just lil guys). Oscar's pretty small right now too, about 4 inches. It's funny, they all get along perfectly.. I even had bettas in there for a couple months, nobody even lost any fins. The lobster tried to beat the crap outta the oscar last night because he tried to steal his food (the lil piggy!), but he got away. The lobster's the only guy in the tank I've had issues with, he hides and then tries to nab stuff as it swims by, but he's waaay to slow to catch anything anyways.