I don't know how to get very good pictures of my tanks, particularly the fish, but none of them are very good. I guess I need a new camera. Any suggestions other than that?

Have you been using a tripod? They're great for keeping the camera steady - you could be moving imperceptibly and even that will ruin an otherwise good photo!

If you want to be able to take really good pictures I'd have to say you need a good camera. Like a Canon. This is the expensive route to take, of course, but I don't know if there's many other options. Photography is an expensive hobby, unfortunately!