I'm not familiar with that particular camera, but can you shoot in RAW format or manually set the white balance? If you can shoot in RAW, then all you need is a raw editor, and you can adjust the color so it looks correct. A shortcut is to put something white in the tank, angle it about 45 degrees up towards the light and take a picture (I liked to use a lid to a 5g bucket or my white cutting board, but anything like that will work). You can use this to either manually set the white balance, or if you're changing the white balance in post processing, there's usually an eye dropper tool where you can just click on the white object, and it will set it for you automatically. Some editors have a batch feature where you can apply this correction to all your photos. Otherwise, just take note of the color temperature and hue and manually apply it to your photos. Unfortunately, most cameras don't have preset white balance settings that handle the very cool color temperatures of our tanks very well.
As for focus, I can't help much with that particular camera, unless it has a manual focus, which is generally what I use for my full tank shots. Depending on how close you are to the tank, your aperture may be too wide, though. Again, aperture is kind of tricky on those point and shoot cameras. The really short focal length for those lenses always throws me off. The good news is, it gives you a much greater depth of field than those of us with SLRs would get at the same f-stop. There may be some depth of field calculators out there that can help you out with that camera in particular.
