One of the dwarf cichlids is your best option in a community aquarium. The Bolivian Ram (Mikrogeophagus altispinosus) mentioned is ideal, as a lone male; or one of the hardier Apistogramma species like A. cacatuoides); your GH is a bit high for wild caught dwarf cichlids that need very soft water.
I will just mention that cichlids must select their mate; putting any female in with a male does not always work, and the female (usually) will be bullied to death. Sometimes it can go in reverse. A single Bolivian Ram does very well in community tanks; my last male lived well into his ninth year (they have a normal lifespan expectancy of 4-5 years) on his own in a tank of Corydoras and various tetras. He ruled the aquarium (it happened to be a 5-foot 115g Amazon riverscape) but aside from pushing some of the cories out of his way when they were trying to feed from "his" pellet or disk, there was no problem. This territoriality is why more than one cichlid species, and more than one cichlid (unless a bonded pair) is unwise even in large tanks.
Byron.