neons are good. 6-7 should do well. balas get to 1' in length and need schools, so they are totally out of the question.if you get neons, all i'd reccomend would be some/a small bottom feeder like 3-4 otos or corydoras catfish, or a BN or rubberlip pleco, but not a regular one, they get to 20" long! have you cycled the tank?