A dream port for me...I've always lusted after the Windows version, and now I love seeing it on my G4 Cube/Studio Display setup. It runs beautifully with a Geforce2MX (~52fps on "flat out" setting).
I didn't hesitate one bit with the $12.95 price...in fact, I thought that was quite reasonable for such a beautiful piece of software. I even emailed Apple and recommended they include Aquarium in OS X 10.2!
Keep up the good work!!