It is a tv screen that flashes different images, and I took a handful of photos and this one of the shark created an intriguing contrast as it does make it difficult to tell what one is looking at.
Vancouver Aquarium lacks a spectacular exhibit anywhere on its 2.1 acres, but it does have a fantastic collection (particularly marine mammals) and there are many solid elements to it. I've posted elsewhere on ZooChat that I consider it to be a strong contender for one of the very best aquariums in North America but it does have its failings.
The coral reef tank in the photo is the largest of the 3-4 that are in the Tropics Gallery, and the tank is approximately 9 feet in height. It is quite deep and it goes back at least 20 feet so it is solid but unspectacular.