Yeah, mine is finished too. I pretty much live down there except coming upstairs to sleep. We keep the poofy recliners set so you can turn from the giant tank on one side to the entertainment center on the other.
Basements rule! They stay cool in the summer, warm in the winter, and when setup right are almost utterly silent. Perfect. I moved the entertainment center downstairs when I used a projector way back when and was never happy on how dark I could make upstairs rooms and then have lived downstairs ever since.
If you're going to keep giant tanks, you pretty much have no choice anyways.
But I do wonder the same thing about keeping tanks in garages and sheds. I don't think that's the same as keeping in the basement at all.