Thank you very much! The key to these shots are in the lens! I am shooting with a Rebel XT and a Canon 100mm Macro lens. I used a tripod, remote (you can use the timer), turned off all the pumps and PH's, cleaned the glass and shot in AV mode with an ISO of 800. It's very important not to have any movement of the corals or the shot will be blurry.
Thanks.