A fish trap!
I have used and had excellent success with this trap. Designed to catch fresh or saltwater fish, the trigger release keeps the trap hands free up to the time the aquarist is ready to catch the fish. The trap can be operated from across a room with only a small tug from a string. The door slides at a slanted angle to confuse the fish as to where an escape route would be. The glass sliding door has enough weight to very quickly slide shut before the fish has time to react. A feeding tube can be used prior and during trapping the fish as a way to get the fish used to eating from it and create a comfortable setting for the fish just prior to trapping.
Here is a cool video on how to use it.
You can pick one of these up here. They work great!
Thanks for stopping in again for a quick read and a view!