Thanks. I’m sad but I really did all I could. If it had been one of the other fish I could’ve moved it to QT and started meds but mandarins just don’t so well in that environment. Kinda thought we were out of the woods with it since we’ve had him a month already but guess not. It was one my husband HAD to have, he told me this morning he doesn’t want another.Sorry you lost him, I am no real help with fish diagnosis, keep an eye on the tang as my guess is that that will be your indicator fish.
edit, when did you last change your UV bulb?