yes the glass is much too thin and will not hold water, I believe that you are talking about a critter keeper of some sort with the sliding screen top right?
I know someone who filled a 2't x 3'w x6'l reptile tank with water to see if it leaked. luckily the only thing in it was water, it shattered when his daughter slammed the front door, 1/4" glass is not enough.
I tried it once, I even laid an extra layer of silicone. I'm actually surprised it lasted two months w/o leaking. One night I came home from work and half off the water was gone. Now that tank is used for a half filled aquatic turtle tank.