The biggest advantage in using a white background is you will easily see the fish. I prefer using white backgrounds for the lower tank in a double tank setup. Normally, the top tank is the 'spoiled' tank. That's where you put your best hardware and fishes because it provides the best view.

Aquarium background is a need Make sure to choose a high-quality aquarium background for a fish tank. It's not that you need to have an aquarium background, the fish are the ones in need of it. You are doing them a favor, and the aesthetic side of this feature is only a bonus for you.