Originally posted by: NuclearNed
I'm wondering if you may be confusing Treasure Island with the Mirage. I don't remember TI ever having a tank, but the Mirage has a large one behind the check-in desk.
Also, Mandalay Bay has a large shark tank that is supposed to be pretty good. I can't remember, but it seems like admission is $10-$15. I've never seen it, so I can't say if it is good or not.
And finally, there is a large tank somewhere in the Forum Shops at Caesar's.
There may be more, but those are all that I remember.