Barrier usually has pretty interesting hunter type wrasses for flatworms. They have 6 lines always, and the last 2 times I've been there they've had hawiian 4 line wrasses, which are even cooler and people say they eat not only planaria, but AEFW and monti nudis as well (at least that's why I thought there was a rush on them last summer).
Planaria flatworms aren't a big deal as long as you keep your water parameters in check. Usually they only show up on something that's dieing.