German Blue Ram, Gold Ram etc, Bolivian Ram, My favourite - Red Breast Acara, Kribs, Apistogramma's or you could go bigger but with less fish - pair of Sajica, or pair of Keyhole's, or pair of Rainbow,s would all do okay with a small shoal of Tetra (min 6) and wider body type for the bigger guys like Lemon Tetra etc. You could also add a few cory's with the Dwarfs as well as a shoal of Tetra, I would personally let the tank settle for a few weeks before adding German Blue Rams. If your going to do South American Cichlids like the rams a lower pH is recommended, adding some bogwood will help.