If you were to log in, you'd be able to get more information on your fellow community member.
I guess "A Rich Person's Guide to Aquariums" isn't the same as "A Sensible Person's Guide to Aquariums." Instead of putting the background INSIDE the tank, try taping it to the OUTSIDE of the tank, perhaps the back of the tank, which would go against the wall. That just might do the trick to eliminating such catastrophes, like your fish dying behind it.