I don't have that camera, but here's some suggestions:
Use a tripod if you have one. If you don't, try putting your camera on something sturdy like a stack of books. (Reduces blured pics)
Use the countdown timer if it has one. (Reduces blured pics)
Turn out all the lights in the room. (Helps camera focus on what's in the tank, not on the glass)
Get as close to the tank as possible, put the camera right on the glass if you can. (Reduces glare)
Use Macro mode for extreme close ups if your camera has it.
Color can be tricky if your camera has auto white balance. If you aim at something bright, it tones down the overall picture, if you aim at something dark, it brightens the over all picture. Try out the photo editing software if any came with your camera to see if you can tweak the colors where they should be.
Just keep playing with the settings until you find something that works for you. You're not paying for film, so go crazy with it.
Practice makes perfect. Most of the time, it's not the camera's fault, but the person behind the camera. Most of my pictures get deleted before they ever get downloaded to the computer.
