WIth my pair I keep bolivian rams, Bristlenose, Neons, Cories, Kulhi's and even a giant Plakat
Have also successfully kept Keyholes, fighters, Dwarf gouramis, blackwidows, a blue acara, a juvenile red jewel with angels.
Basically you can keep anything with them as long as they are small (id say less than 3''), theres plenty of room, and arent fin nippers (like tiger barbs)