I have to admit I can't take credit for this. This DIY video was posted by a pjtomo on Youtube YouTube - How to make a fish trap for reef aquarium.
. He basically shows how to make a fish trap with just a 2 liter bottle of soda. I didn't need to use the glue for this. I was going to buy a $30 fish trap before I came across this. I needed to get a Chromis that was stressing by Blue Tang out of my tank. I put the trap in and within 25 minutes the blue tang came in the trap and couldn't get out. Within a minute after that the Chromis came into the trap and couldn't get out. I took the blue tang out of the trap leaving only the bully fish in it. Mission accomplished.