going to Vegas

I would recommend Mandalay bay it has an awesome aquarium. They offer a behind the scenes pass at certain times of the day. Its right next to the Luxor. Have Fun!!!

 

mandalay bay has many aquariums including a shark reef but yeah the behind the scenes tours would be great as well as just seeing everything they got

 

I know the Mirage has a tank that runs the entire length of the check in/out counter... but the last time i was there (over 1 1/2 years ago) they were doing some construction on it so it wasnt running and they had boards in front of it. I know a few of the hotels in Vegas use a large water tank truck to go to San Diego to get water from Scripps/Stephen Birch Aquarium (Random needless Fact)

 

there are other random aquariums at some of the hotels and restaurants but those two, mandalay and mirage are the two to see! heres a little more info on both from their websites. and check out the link to the shark reef, its a tour!

mandalay shark reef 
EDUCATION
Shark Reef offers a comprehensive educational program for students of all ages. Two sessions are conducted daily Monday thru Friday. The program includes a 1-hour guided tour of the aquarium as well as a 1-hour classroom session conducted by our Education team. For reservations or more information, please call 702-632-4555.
CONSERVATION
Several initiatives are taken by Shark Reef to encourage the message of conservation and preservation. Recycling facility water and implementing imitation coral into exhibits to preserve natural resources are just two of ways Shark Reef sets the example.
MISSION STATEMENT
Shark Reef is dedicated to establishing and maintaining the highest standards of animal care, to providing its visitors with an entertaining and educational experience, and to the practice of meaningful research and conservation initiatives. 
mirgage website:
One of our most popular attractions is the aquarium located behind the Front
Desk. This 20,000-gallon saltwater aquarium is home to angelfish, puffer fish,
tangs, sharks and other exotic sea creatures.
Managed by The Mirage's own in-house aquarists, the aquarium
accommodates more than 1,000 coral-reef animals representing 60 species
from Australia, Hawaii, Tonga, Fiji, the Red Sea, the Marshall Islands, the Sea
of Cortez and the Caribbean. These sea animals were all selected for their
adaptability to the environment and compatibility with other species.
One of the most elaborate and technically advanced aquariums in the world,
the tank is 53 feet long, eight feet from top to bottom, and six feet from front to
back. The acrylic used in the aquarium is 4 inches thick. The interior was
carefully created to simulate an intricately detailed, artificial coral reef. To
preserve the living reefs in the ocean, no live coral is used in the tank.

 

Caesar's Palace has some if I recall correctly.

 

Mandalay Bay- main large tank at the end of the aquarium tour is designed to look like you are inside an old ship looking out is really nice if you like larger predator fish. sharks and barracudas were nice. quality was close to shedd aquarium although not nearly as large. worth the ticket price.
Ceasar's palace. At the center of a shopping area is a display with statutes and fire. Next to this is a huge round aquarium. This tank was packed with very nice fish from small to very large. I wanted to spend an hour there- very nice.
Treasure Island (or right next door if I remember)- tank behind check in desk with 100's of clown fish.
This was about 4-5 years ago.

 

saltwater tank at Ceasar's is called Atlantis- 50,000 gallons.