Greetings from the Critique Club Mr. President
And you're not just the President, you're also a member!
Oh wait... wrong club...
Composition - My first impression of this shot is that it is a really tough shoot. I've tried several times to shoot my fish in a much much smaller tank, generally unsuccessfully. The composition of this shot is pretty good and not really yielding too many problems. The colors are very good and the other fish in the water makes it a little more realistic. At least I think it's another fish.
Technical - Sharpness - This is the major problem with this photo. The slow shutter speed would have to have a perfect pan technique to properly portray this killer. It would be a 1 in 10,000 shot if you could get it. Its damn near impossible to ask him to stay still for that long as well. The lighting is actually pretty good in here for the circumstances. I'd expect it to be darker, unless you PS'ed it lighter. The framing is really very good.
Overall - The water looks like it came from a painting. The shark looks a little fake on it, but by the movement of it, I'm sure its real. A very tough shot to do. Its done adequately but not exceptionally. And I think that all boils down to if you could make it sharp enough. You'll have to make another trip to this aquarium and try a few more shots. It'll be worth it when you get one. Good luck and keep shooting. - BoB
NIce emotion, and good capture. Not sure what camera you're using but it seems out of focus... (My guess is that this is behind glass and it's not really you're fault.) Interesting subject. Good job.