Well they appear to be a peaceful community fish so I would go with more peaceful cichlids that don't grow as large as they do (~12"). Any of the dwarf cichlids would work (rams, apistos, checkers, keyholes) or even could try convicts or firemouths. When you get into GT and Jacks, they might be too agressive. Sevs, might be a little on the aggressive side along with the size. And I think Oscars would be too big but might work if they grow up with them from being little. Geo's could be ok but I don't remember how big they get.