There are several arguments on what will do the trick, from copper to freshwater dips. But the 100% basics are that this is a parasite. There are high relations towards it, and other parasites and diseases, from poor water quality conditions. This is a huge stress on fish as ammonia and nitrites can burn girls. This can start from capture and work its way from transport to the LFS
and then into your tank.
When dealing with parasites I say treat it all like ich. 6 weeks fallow display should do the trick. Then ensuring that the parameters are pristine and stable.
Parasites that deal with our fish do not have any interest in the inverts that we keep.