[Could he have been fighting with any other fish, such as a royal gramma perhaps? My Flame Angel had pink lips briefly, which probably happened during a skirmish with my Coral Beauty or Royal Gramma.]
[Sorry to hear about that - had a scopas that had the white cottony looking stuff on lips and around the dorsal. It died as well. Dang. However, learning for the future - fungus disease.]
[Someone PM Amanda with a link to this thread, in case it is something she can identify. That way if a similar situation occurs, we can give people the correct solution to save the fish.]
[Fungus is a possibility, though it is quite rare in marine tanks. If so, treatment with malachite green may have been effective, but I am always hesitant to advise that.
[Sorry to hear of your loss. It hurts me every time I hear of a loss. What about this. Could he have tried to eat a bristle worm? I lost a damsel to what looked like cotton spikes around his mouth. An autopsy (come on you know what I mean) showed that the white cotton looking things were very small and hard spikes. Only thing I could think was a bristle worm. Just a thought.]