for what i understand these guys can be escape artist. that being said you can often find them before they die, i have read things saying these guys have been found climbing up bathroom walls. don't know why.
as for my personal experience with them is i have them in tanks with open lids and closed, the only time one got out was when i pulled and orinement and he was attached so it was my fault. i think as long as the water is fine you know cleaned regularly they really don't hae much reason to leave.
good luck with them, i am very fond of these little guys.