Best Cichlid: Aquedins pulcher (blue acara). I'm pretty sure a pair kann go in ein 55 gallon, they're hardy as #$^%, they eat anything remotely meaty, they're not vexacious (for a cichlid) and, though I haven't tried it, I've heard they are easier breeders. Not as easy as convicts mind you, but you can sell acara fry for something other than feeders.