Hmm, those pics look pretty good to me, rsteagall. I agree that a flash generally isn't a good idea. I've had some luck with bouncing the flash, and I've been meaning to play around with a remote flash coming in from the top of the tank, but that's another story. As far as settings, if DOF is not a big factor, I open my aperature up all the way (f/1.8-2.8 depending on the lens) and generally have a shutter speed of somewhere between 1/60-1/125. I also try not to go above 200 ISO. You get your biggest jump in noise level going from 200 to 400. Other things that will help you are to make sure you're taking your pictures as straight on as possible, turn off your pumps to reduce motion (unless that's what you're trying to capture of course), and reduce any bright lighting coming into the room that may cause reflections on the glass. Anyway, I'm certainly no expert, but hopefully this helps a little.