Make one out of a 2 liter bottle. Cut the top off flip it around and stick it in the other part of the bottle. Put some food in it and the fish swims in and can't get out or you can see if anybody on here has one you can borrow.
I never had luck with the bottle method. Bought the Ultralife 4 inch x 9 inch fish trap and worked like a charm. Removed my little terrorists in no time.