Melanurus wrasse will do the job. Flatworm exit is another alternative. However, I warn you be careful and follow the instructions on the package and be very very careful. Please don't listen to people when they say it's safe and you won't have ANY problems. I used it several times over the last several years with great success, however one time during a bad infestation I did end up losing several high dollar fish.
I would suggest you get a turkey baster to blow the dead worms off the rocks and a fish net so you can remove as many dead flatworms from the tank after you apply the Flatworm ext. The worms are toxic and will reek on your tank. Like I said follow the instructions and follow the recommended waters changes after use you'll be fine.