It's a beautiful fish and it's been well documented for flatworms. However; each fish has a different personality. Hopefully it finds your flatworms tasty. Like most wrasse; it needs a place to burrow in the substrate to sleep at night....or at the very least lots of hiding spaces in rock work. Quite hardy and animated.
You'll find it will also keep other pests in check as well. It will pick at your rock work for star fish etc.
Red lined wrasses are great too for keeping pests in check.
*Note....they (wrasses) are jumpers when startled. Try and have your display enclosed if possible.