I wouldn't put Bettas and Angels together. In a 10-20 gallon set up (which I am gonna do fr my betta) I would put the betta with some small cory catfish and or maybe some neon or black neon tetras. You could also do guppies (using caution because of fancy fins), mollies, danios or platies. Of course all suggestions are with caution. Bettas can be very particular and, like people, have very varying personalities.