Help Identify

[Shawn4105]

Need help really identifying this on tang, has noticed he darkened in color and stayed at back of tank then two days later this appeared. He is swimming and breathing fine now in hospital tank. Just unsure what he has any help would be great.
No new fish or coral added to tank tank been

same for few years now.

 

[vetteguy53081]

Need help really identifying this on tang, has noticed he darkened in color and stayed at back of tank then two days later this appeared. He is swimming and breathing fine now in hospital tank. Just unsure what he has any help would be great.
No new fish or coral added to tank tank been

same for few years now.

Looks like idiopathic mucus spores but hard to confirm with fish out of water.
Is that a flatworm on fish or coralline on the glass right before its tail?

 

[Jay Hemdal Verified Community Expert]

Need help really identifying this on tang, has noticed he darkened in color and stayed at back of tank then two days later this appeared. He is swimming and breathing fine now in hospital tank. Just unsure what he has any help would be great.
No new fish or coral added to tank tank been

same for few years now.

Are you talking about that long line? Can you get a picture of the fish in water?
Jay