Uh - you're supposed to tape the mirror to the OUTSIDE of the tank!

On a sidenote, regarding some of the other replies: why would anyone,
ever, *want* their cichlid to become psychotic?
Anyway, if you want psycho fish, get yourself a male and keep him all
alone in a big tank. As he matures he'll grow hyperaggressive and be
impossible to keep with other fish; he'll even try to attack his owner
through the glass. Which apparently somehow is a good thing.