This happened to me TODAY, right in front of my eyes.
Woke up this morning, got ready and went down to check on the new additions to the tank. Yesterday I added a Blue Spot Jawfish, Algae Blenny and a Leopard Wrasse. All of them were in there hanging out, I was more concerned about finding the Wrasse this morning because I know they bury themselves at night. Then all of a sudden and explosion of water and the Bluespot jawfish laying on top of the fish net. Couple flops and I caught him before he hit the floor and I opened the net and dumped him back in. He seems unaffected but how the heck did he get through the 1/2" square? He seems fatter than 1/2". Only the expensive fish like to jump, its never the fish we don't like.