Five time escapee. I overestimated my tank. I had a 20g aquarium run with a light that stuck through the screen. The little RB managed to squeeze himself between the screen and the light (never burned) and slid out underneath the plank of wood that I used as weight. Twice in my closet, twice under my bed, once behind the bookcase. Since then, he has had no chance to escape. I have about 20lbs worth of books on his 40g, and the only spot that isn't covered with wood is covered by a screen. This thing is ghetto, but serves the purpose.