Cichlids in general and ESPECIALLY tiger oscars have a personality. I had an albino tiger oscar once who was the biggest jerk in the world and would leave nothing to peace. And then again I have had several others that were the biggest sweethearts (for lack of a more manly word) in the world. Its true that you can teach a oscar tricks, a guy i knew rang a bell every day for about 4 months and then set it on the lid of the hood, after a while the cichlid cought on, when he wanted food he would bump the lid of the hood ringing the bell, amazing!! =)
Another thing, as you know oscars get rather big, and we all know that pretty much any fish is better in pairs or more as long as there is room, if you have a large enough tank the more the marrier! An example with tiger barbs, because I used to have alot of them, if you put one tiger barb in a tank of say mollys then he will most likely pick them appart, but put 10 tiger barbs in a tank that is big enough (key point) and the tiger barbs will keep more to thier group since they are a schooling fish and mess aroudn with each other rather than the other fish, note that this is in "most cases" once upon a time they all ganged up on a poor pleco, but he was on his last leg anyway.
Hope that helps in some way or another....