Egg crate may not work depending on what fish you have. I had a Midas Blenny do a perfect jump right through the egg crate onto the floor... I didn't find him in time. All my tanks that have fish now have either mesh lids or glass.
I have had a lawnmower blenny, a midas blenny, a clownfish, and a orangetail filefish jump out! The only one I caught in time was the filefish.