When you are going to purchase one (this includes any in the genicanthus group) the main thing to look for is swim bladder issues. Make sure they are not fighting to stay down (these fish are collected from deeper down). The female lamarks and female swallowtail seem to be somewhat ok in this department, but all else seem to be touchy. There are two species of genicanthis that get sold as the same, make sure you dont get them mixed up. There is the swallowtail (Genicanthus semifasciatus), and the black spot (Genicanthus melanospilos). The female swallowtail has no face markings, but the blackspot has a mask. The males look somewhat similar, check pics online. I have seen some awesome tanks with harems, but a fish that needs to be QT, and kept in a big tank. I have used hypodermic needles on fish with swim bladder issues - it seems to be the only solution, no sort of meds have any effect. Anyways, if you have a big enough tank and are willing to QT, it is a stunning look.