A Brim (Bream) is what we northerners call a Bluegill, Or a similar fish from the same family depending on who you talk to. I concurr with the fact that a 29 is not big enough for this fish with or without an oscar. They are really tough, so he may not have problems but he would be much happier in a big tank. There is little if any info on These fish for aquarium purposes, but I can tell you this from my experiences as a kid. The Bluegill has been peacefull in your tank because he has been in charge, and he isn't too hungry. They are awesome fish but most of them I ever put in an aquarium wrecked everything eventually. Common problem with Oscars as well if you aren't prepared for a big srong fish. I have always wanted to set up a big tank and put in some Bream and maybe even a bass and a channel cat. it would be awesome to see one in with an Oscar, and I think they would get along just fine. But unless someone has tried it and can say it's OK. I would ty it but I would be very attentive when I first put them together. Bream are an attitude fish, they fight harder pound for pound than almost any fish in the world. I have seen 6" bream protect their nest against some really big fish they don't back down and the don't quit. IMHO the Bluegill and sunfish here in the US have a lot of similar behaviors to the Cichlids in Central and South America. Obviously there are many scientific differences, but they remind me of each other a lot. Good luck.