There is no lid on the tank. I used to use metal "mesh" with 1.5" square holes when it had my large fish in it before the leak.
Egg crate would work equally as good and provide you that piece of mind that your fish aren't going to make a jump for it. Do you plan on doing anything with a lid for it in the future?
Looks like a disaster waiting to happen. But sounds like you've got it under control. Nice GG!