Bottle trap: there are various ways of making them. I've used a wine carafe nestled deep among rocks, with a delicious treat inside. Fish goes in, you net the neck, lift out.
Some people make them with plastic soda bottles: cut off neck and part of bottle as a unit, reverse same so it juts into the rest of the bottle, superglue together, bait, and wait. The narrow inverse opening presents a little difficulty getting out and the transparency somewhat confuses the fish. Wrasses, however, are nearly as clever as eels about learning about a trap. Be really ready to make good on your first try, because they're canny little fish.