Abstract: A decorative background assembly for an aquarium, having a plurality of interchangeable illustrated display panels, for enhancing the appearance of the aquarium. The assembly has a waterproof housing which encloses a frame which selectively holds one of the display panels. The housing also encloses a fluorescent light fixture and an angled mirror in proximity to the light fixture. The housing has hooks for selective attachment of the decorative background assembly to the rear wall of the aquarium. The fluorescent light fixture and the mirror are mounted in proximity to the lower portion of the housing. In use, a user chooses one of the illustrated display panels for insertion into the frame. The user then selectively attaches the decorative background assembly to the rear wall of the aquarium by fitting the hooks over the rear wall of the aquarium. The fluorescent light is then illuminated, thereby illuminating the display panel with light reflected by the angled mirror.