Dwarf as in 3-4 inch size?
If so, then start with German Blue Rams, or another Dwarf Ram Cichlid variation. Get about 5 or 6 and put them in the tank together, along with one or two flat rocks/slate. Eventually 2 will pair up and breed. It will take about 5-6 spawns before you get any living fish out of it though. With you tank size I would imagine you shouldn't have to remove the other fish. Just keep them well fed so they don't try to snatch any fry.
If you're not talking about real dwards, go with convicts.