Some random ideas:
I haven't done much aquarium photography but I've found the point and shoots get great pictures when lots of light is available. They are usually pretty good with close up macro shots. I suspect with aquarium glass you will want manual focus controls though which almost all point and shoots are terrible at.
- the Canon Gxxx "pro" point-and-shoot line might have the manual controls you want but doesn't have the large sensor of the DSLRs wiith interchangable lenses
- the micro 4/3s system from Panasonic / Olympus gets you interchangable lenses (some really nice ones too) in a small package
- The Camera Store in Calgary will rent out cameras and lenses so you can try them
- Try the Camera Finder on Flickr to see what is possible. Pick a camera then search for aquarium-type keywords. For example, here are some decent pics from an iPhone:
http://www.flickr.com/search/?q=clow...ple%2Fiphone_4
Some good sites for research:
www.cameralabs.com (more practical, good comparisons)
www.dpreview.com (more technical)