Really nice looking so far, got it spot on again.
Had a thought today while thinking about this project.
Had you considered filling the inside of the tube, and if so had you considered using slightly coloured geletine ?
Would hold the body in place whilst giving the illusion of water ( especially if you could infuse bubbles while it was setting).
You would probably need to seal it as I don't know how long it wouls last if exposed to the air.
Just a thought