My wife and I have been there before and loved it. It is a very small but very charming place to spend about and hour or so. I think it was about 6 or 7 dollars to get in. Its is located in Mallory Square. The first time we went we got a crusie guest discount and last January the did not offer it anymore. Always worth asking though. The admission is good all day you can come and go as you like. The guided tours of the aquarium are fun. we look foward to key west every time we go there just to visit the Aquarium. I tried to post picture last time but it did not work.
Feel free to E-mail us if you want to see a few pictures of this neat place.