I was thinking about it and if I were to do it I would have it protrude halfway out of the wall, but it would have to be custom acrylic with all rounded edges on that side and that =$$$$.
back in '82-'84 I maintained a custom tank built into a wall. It was about a 40"x 40"x12" square of black acrylic with a 36" bubble on one face. The bubble was all that showed through the wall. Unfortunately there was only about a closet's worth of space to work with behind the tank, so it wasn't much fun to work on it.
add to that the wall paper was leather that cost $50K in 1980 dollars
We panicked every time we thought we were going to spill a drop.
Penthouse magazine used that condo a few times for photoshoots. Unfortunately I never got to clean the tank on those days.
sorry, I'm rambling on again... I'll stop now