Oooooorrr, I just thought of this. I'm not big on themed tanks usually, but in your case I think it would be super cool. Whatever kind of dealership it is, you could probably get a bunch of die-cast cars of the current body style that they sell there. You could even set up a little fake city street on the bottom of the tank and change out the cars from time to time and that would be awesome. Get the diecast cars in bright colors that match the cichlids! (you probably have to epoxy or urethane coat anything that goes in there that wasn't intended for an aquarium..)