To tell you the truth, for quite awhile I had them in an uncovered tank. I know, bad me! But I didn't really have a choice. Anyways, they didn't jump out! However, when I was transferring them to a different tank one time, one jumped straight out of the cup I was moving him in.... soooo I guess you'd have to decide if you wanna take the risk for yourself or not.
And ryan - I hope you can find some, they're great fish!!
I just saw some for the first time today!
They look just as cool in person....although the ones I saw were not nearly as nice as yours..... They were only 3 dollars each though.