So your using the egg crate to trap the fish in with the mantis now?! How diabolical. Mwhahahaha!
Do you do this for video purpose? Or is this how your planning on feeding? I wonder what changes the mantis will make to its home based on how the fish respond to the tank without the use of the egg crate. For instance will mantis move it's hole more to the center of the tank, or will it create more than one surface shoot, or will it just keep the hole it has and wait till the fish swim by? I know in the past I have had fish that never leave a small area of the tank they are in due to fear of being bullied by other animals. In your tank they have no cover and are always in view of the mantis. So some interesting things may happen. I also don't see feeding humbugs in issue any longer for you. I know the Doc feeds them a lot, well at least he shows a lot of great shots of them being taken down. Poor angry little fish.