How to take good aquarium pictures?

i have a pretty old (about 3 or 4 years) Konica Minolata Dimage X20 thats 2 megapixels (yeah, there are cell phones out now that are better). but i can get pretty clear pictures without the flash. i just off the room lights and utilize the tank lights. if theres not enough light, my camera will lag about 2 or 3 seconds and i have to hold very still or the picture comes out blurry. but the tank lights are bright enough and i can get away without flash and the glare.

The best way I got pictures was at night with the lights off and the tank lights on. The camera has to have the flash off AND be on a tripod.
Thats the only way I've been able to get some great shots.

No flash, set your shutter speed at no less than a 60th of a second, and set your aperture to the lowest number possible. You didn't specify the kind of camera you have, so I'm not sure if you can adjust these things. If there still isn't enough light with no flash, and tank light on, set your camera on the edge of something hard and steady and lower the shutter a little bit, but you're risking blur if you don't keep the camera very steady.

If you can't adjust these settings, turn off your overhead lights, turn on the tank light, turn off the flash and shoot the tank at an angle from 2 or 3 feet and zoom in, holding the camera very steady. There should be a setting on your camera (if it's not manual) that will adjust for ambient light. That's the one you want.

Is this a Canon DSLR or a point and shoot?

If it's a DSLR, you'll need a macro lens. If it's point and shoot, switch it to macro mode and center focus. Turn off the flash. Don't zoom. Get as much lighting over the tank as you can manage and turn off other lights in the room to prevent glare and reflections in the glass. Set your camera to manual mode with a shutter speed of 1/60, an aperture at f/3.2-3.5 or thereabouts, and an ISO of 100 or 200 (will depend on the light in your tank). Play with the numbers from there to see what works for you.

-First you'll need to make sure your glass is crystal clear.
-For nice shots, a macro lens isn't necessary, but you will be able to obtain much more detail with a macro.
-If you have the capability to choose how many focus points you're using with your autofocus, set the camera to use all of them. That way, it will focus on the fish wherever it is in the frame.
-Pay attention to what's blurry. If the shot looks blurry, refocus the camera and try again, don't just shoot and hope for the best. This way you can avoid the typical endless blurry photo after blurry photo routine.
-You'll probably have the best luck with a high ISO. If you have a 20D or a more recent model, you will be fine even using 3200, but 800 will of course be less noisy.

Flash setup:
--stand at a 45 degree angle to the glass.
--if you have servo capability with your autofocus, i would recommend using it. otherwise, if you have experience with manual follow-focusing, use manual.


Non-flash setup:
--open all windows, turn on all room lights, throw as much light at the aquarium as possible. however, pay attention to the reflections on the glass. you'll want to eliminate as much glare as you can. move around until you find a clear spot.
--try using time-priority, set at a minimum of 125. faster is better, but how fast you can shoot will depend upon the amount of light you have.
--again, use servo or follow-focus.

Good luck! Post your results so we can see!