I brought my parents and relatives here because I couldn't gamble any more and needed to find free entertainment to keep me occupied. *haha* I had heard that there was a mermaid show here, done in this giant tropical fish tank. And off we went.
The tank is rather nice, with a good assortment of aquatic fish. The walls around the tank have framed mermaid themes artwork. The "show" however was just so-so. The costume was rather cheesy, though it's family friendly, as you saw small children wave to the diver dressed as a mermaid. No fancy swimming or anything.
But it's free, and it's something to do. *haha* It's at the southern edge of the strip, so perhaps make a trip there on your way in or out of Las Vegas.