I don't mean to mess with any ones having fun, this would be a interesting novelty ...
Some one has done this before, has one in his fresh water tank. (Weighted his down with lead cased in epoxy).
At any rate he has in in a fresh water tank at his job site, says he has to pull is completely out and clean it at least every two or so weeks and a half if not more ofter, says it's worth the trouble and he likes it. How ever he had also tried it in his reef tank at home. Ran into these troubles.
1. Putting it in and out of his reef tank so often concerned him
2. White balance was hard if not impossible to control due to high out put lights of his tank
3. For what ever reason, he never found out, pods congegated all over the thing constantly, obstructed field of view
4. Had to chage out the plexi lens after 2 months, began to be come opaque, also never found out why, happend twice and gave up the endavor.
5. Found it looked ugly as all get out
However he did come up with another design that if I come across I will send, took a pen cam of sorts on a flexible probe, spent a few hundred I imagine or so I belive, it was rather tiny and had some sort of optical zoom function, he attacted 3 tiny LCDS to the thing a white one, red one, and blue one, had them where he could turn each one on and off individually, used to run the thing in and out of the LR in his tank and behind stuff to check out the macro world, and even located his missing shrimp in the back corner of his tank that couldn't be seen otherwise. I can't see any practicle use for the thing, cept maybe hollywood movies, safe cracking, spying, plumbing, ?!
http://www.4hiddenspycameras.com/wir24colpenc.html Theres a though, how well do radio waves transmit though shallow water?