Small to medium sized african cichlids, I think are the way to go. Have a rocky outcrop in the back, some robust plants and a few africans like Julidochromis, Brichardi, or similair. Another good choice to go is labyrinth fish in a well planted tank, dwarf gourami, maybe a paradish fish, or in place of a paradise fish, a betta (bettas if females) and spike-tailed paradise fish (Days Paradise fish). Labyrinths and Africans are both very colorful and full of personallity (for the most part).