L, thanks for the kind words. The 105 macro IS going to be the best lens you can use (do you have the old one or the new VR? that is an amazing lens). All my photography is done with an overhead flash triggered by a wireless controller. With Nikon, it would be 2 flashes, a SB800 working as a trigger on the shoe, and a 2nd Nikon flash on the tope of the tank, looking down. For much more info, check out the BEST site ever on this subject (I actually started it years ago), called
The Aquatic Photography Forum.