This image was taken using my new toy - a Nightsea Bluestar torch and filters (nightsea.com)
The torch emits a high intensity blue light which excites the natural fluorescence in the Zoanthid corals. The filters allow the camera to capture the fluorescent images.

The trick here is to turn off all the pumps in the aquarium to keep the zoas still. Then shine the torch to illuminate the coral through the side of the aquarium. Keep the camera and lens at 90degrees to the glass to avoid distortion.