IMO it's about usage of the space. Have you thought about instead of it being just in wall, doing a build out around the tank. Like a bookcase style build out? Not sure how that would work, look in the room. You get the benefits of in wall with regards to hiding everything. Since this is a home office, i think it would look good to build a usable shelving system around the tank.
some google pics of what i am suggesting:
Now if you want to go 'baller' style!!