The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.
I'm not sure, maybe larger tetras, but in a 47 gal tank I'd be wary of having the shark in there with community fish. You'd need lots of hiding places and even then I don't know if it would work. The shark will become very territorial and it will want to keep most of the tank space to itself. Just something to think about.
Your tank is not big enough for one RTBS, IMO they would need 75 Gallons. Try a rainbow shark, which is although semi-aggressive is still considered a community fish. Try serpae, kerri, emperor, black skirt, or any of the big and fast tetras.