Well this isn’t good. Was supposed to support 1000 pounds per shelf. Would plywood on top of the shelf help distribute the weight more to prevent bowing?
I’d drain it and get a new stand. 0% chance that can support the tank, and most definitely not on the wire alone. Maybe with plywood supporting it. But I’d still not chance it.
Yea if you don’t want a new stand I’d at least get some wood that touches all 4 edges of the stand frame. The structural part of the stand is probably sound but the wire is not serious load bearing; maybe full of pantry items.