a 2 lit soda bottle works well.
cut the top so fish an fit in. then cut top again where it starts to taper, then invert it like a funnel and secure it. tie a string so you can pull it up.
This hippo has seen me change my fish from large ones to small so he isn't going for it..as soon as you go next to tank hides in rocks. I have to much corals all over nit going to wreck my tank..patience.
I caught every fish today with new trap and nori clip..hippo didn't go near it. Didn't even need trap door fish couldn't figure how to get out while fully open... hopefully Wednesday is the day....