Aquarium shots are very tough. The only way I was able to get decent shots at a place like this was with 800 ISO (froze the motion, but lots of noise). Not sure what you used here, but it works. I like the overall darkness of this shot, and you managed to get good focus and a fast enough shutter speed on the shark. - 9 - Mav
great light/colour on the shark, but the motion blurs in the bg are bit distracting! I like the sense of depth the crop and vertical shot create though.