Naso Tang with black spot on tail

[anemoneguy]

Our naso tang has a black spot on its tail. We just noticed it today. Does anyone know what it is and how to treat it?

 

[ThRoewer]

Looks like a discoloration. Could be caused by a sting from contact with an anemone or coral.
Though a precise diagnosis is hard from a small picture.

 

[Skim]

Looks like he's still just a baby, I think he is just entering puberty. Some Naso Tang's will get a black line on the tail that flows from tip to tip, I no expert but if you look at pictures of them you will see it. I don't know if its a sex difference or just from different parts of the world. I would not be worried about it, your baby is growing up.

Skim