Yeah, I was noticing that nobody else really answered your question, or even tried to. It was a legitimate question and I figured somebody ought to make an effort. Anyway, I'd use a telephoto lens so I could back off well beyond minimum focusing distance and zoom in on it to make it look like it was taken from up close. You'll need a tripod to do anything with the zoom lens, because they can't be used handheld when they are zoomed in like that without getting motion blur from hand tremors. Then, of course, you also need the tank and the background, which will be INSIDE the tank. This will hide any of the top of the tank that might show up in the frame if the background material were to be used outside the tank. I'd use two lights, set up about level with the camera and about 45 derees off to either side, so they don't reflect in the glass, and I'd want at least 250-watt bulbs in each one. Anyway, that's how I'd do it if I were going to do it in a studio.