500g? motoro and teacup rays, teminsis and mono peacock bass, wide bar dats, lots of Geos, black arowana, some oscars, lots of plecs, lots of driftwood, sandy bottom.
you could basically get anything you wanted except the larger growing catfish species even though with a 300-500g you could house them for a good long while until you had to build a pond.
yeah when these guys are breeding they throw out some nice colors and in a 500g you could most likely have some large tankmates as wellwith lots of driftwood for sight breakage and hiding spots that would be cool looking tank
All of these cichlids range are pretty big aggressive fish. (except for the salvini) and IMO are some of the most attractive fish on the market. make sure you do your home work on these guys though. salvini might be too small to go with the others. And Texas cichlids have the don't get aggressive enough to fend off these other aggressive fish until they're about 4-5in.
do some home work on reducing aggression levels no matter what fish you decide to get but especially if you end up with a parachromis