I leaved with a friend who had a 55g (long) fresh water tank w/ 1 african Cic.
One day (a Monday night, right as "Monday Night Raw, a wrestling show") the fish got angry, slammed himself repeatedly into the glass (swimming from one end to another and just ramming it).
The tank cracked and began to eject water from several cracks onto a hard wood floor (actually the hard wood floor was a saving grace).
The first thing my roommate did was scream "get the buckets".
We drained water from the tank quickly (to relieve presure, thinking it would explode any minute, it never did actually "explode").
Removed the fish (still tring to save it, thought it died weeks later acclimating into a new tank, it was an old fish though, she had it for more than 5 years).
Used towles to dry the floor, and so one.
It was a memerable experiance.
I now have a 180 in an upstairs Condo. (Don't ask how I got it up there, when I move I will just end up giving it away to anyone who can move it).
If it cracked...., lets just say I would be died.
Damage could be very expensive given the size of the tank.
The bigger the tank the more possable damage.
I risk we all take.................