First of all, is the tank cycled? (and are you familiar with the
nitrogen cycle?) If not don't add any other fish until it is done.
Also barbs like to be in shoals so you should get at least 3 more Cherry Barbs. They will be much more active and interesting in a larger group.
Assuming the tank is cycled and you have a complete shoal of Cherry Barbs, you have a LOT of fish you could potentially get. Maybe if you had any in mind that you like, we could help you figure out which ones would be suitable and how many to get.
