Keep in mind what you want to focus on. A black setup frames the display and that's what you will see with little distraction from the stand. The white will draw your eyes away from the fish and corals. The eye tends to see the biggest brightest color first and gets pulled that way.
Ever look at a TV with silver surround, then a tv with black surround? You really notice the frame in the silver, but only the picture in the black one.
So, I would suggest black. (BTW, I'm a decorator
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