That was what my post is about.What I’m more curious to know is why are certain species like the Powder Blue, Brown, White Cheek, Clown, Achilles, maybe a couple others especially known to be ich magnets over the Zebrasoma and maybe some select Acanthurus species? Not sure about Naso.
I have a Pakastani butterfly that has many of the behavioral patterns that I have seen with Powder Blue/Powder Brown tangs. Once I was able to correct the problem of the fish sleeping my Pakastani started to recover. Maybe it is that these fish are more prone to this behavior because of their collection origins or because of their species. Maybe something else is at play, I don't know. I do know one thing the ocean is a mighty dark place at night. There is a reason night diving is advanced and that you carry a back up flashlight when you do it.