Help needed! Whats this?

[pangking]

Thanks for all you guys!!! I'm getting little bit more understand and confused now.
If I'm set up a QT, do I need catch all the fishies out, or just one fish that shows infection(only hippo tang shows the sopts on his body)? Catch all the fishies seems too hard for me.
As "fkshiu" said,the parasite will die if it lacks any fish hosts..., So if some fishies still in the tank, the parasite will not going to die anyway, when I put QT fish beck to the display tank, it will get the ICH again?
crying......