Unfortunately, one isn't allowed to take pictures inside the Castle, so I don't have any photos of it to show. But I have heard chatter that a reality show about custom aquariums (Tanked?) did a segment on the Castle tank, so keep a watch out for that.
It's worth noting that the earliest version of Houdini's Water Torture Cell presented the apparatus as, yes, an aquarium! On April 29, 1911 Houdini performed the escape as part of a one-act play in London called Challenged or Houdini Upside Down. The purpose of the playlet, which was performed only once, was to copyright the new effect. In it a "multimillionaire sportsman" named Tim Connor eyeballs his clubhouse aquarium and concocts the idea of locking Houdini inside it.
Connor: Well, my idea is to put this Houdini fellow into that aquarium head first, understand me, head first, with his feet in the air, then put a lid or cover on, fasten his feet to this cover and lock him in. This is my challenge, in the rough of course.
It's kind of fun that after 100 years the Water Torture Cell has returned to its original purpose as a private clubhouse aquarium.
UPDATE: Houdini aquarium revealed on Tanked.