My kiddo is a big fan of aquariums. We drove to the other end of the strip to check this place out.
Mandalay Bay is a large and beautiful hotel! The aquarium is reasonably priced at $20 but is rather small. Much of your time is taken up at the beginning where you are herded into taking pictures that are sold to you at rather high prices. The price we all pay for family vacation photos.
Aside from the tanks there are gorgeous bromeliads, statues, and other tropical greenery around. There are also a number of non-moving reptiles to look at. They're not sleeping, they're just not moving.
Had I known it was such a small place, I would have taken more time going through it. Near the end, there is a place to sit. As you look up, you can see the sunlight breaking through the water as sharks circle around. It's quite majestic.