I know a leo wouldn't be able to escape from the tubs I'm getting, but I'm getting lids (with mesh screening) anyway just so I don't have to worry at all about escapees while trying to get to bed at night, and to keep my cat out. So far my cat has shown no interest in my leos that I have in an aquarium though, but better to be safe than sorry. My cat seems much more interested in my mice and crickets. Once in a while I take a cricket out for my cat to play with. She loves it! And she's so cute when she plays with them!