Fill a strong plastic bag (LFS fish bag) with some sand and lower it in to the bottom and leave the top open. Attach string to the top of the bag. Let the opening of the bag sink down, but ensure the opening stays open. Wait until the fish enters and then pull the string up. It will end up in there, just takes time.
You might even put enough sand in there that the wrasse dives into the sand.
This is what I use to do when I had many electric yellows (freshwater cichlids) to catch - I would place a clear plastic bag into the tank and weight it down with small rocks so that the open was kept open. The fish would inevitably swim into it and I then pull the bag up.
You can use a stick to herd it into the bag if you want it out faster.