Black spot

[mandzhalas]

My foxface developed black spot on the tail two days ago. It's quite large, size of a ballpoint tip, looks like a mole.

Fish have in the tank for two weeks after quarantine. Active and feeding well.

During quarantine it went through 30 days of copper, 12 days of metro and 14 days of prazi.

What is that thing?

 

[Jay Hemdal]

Looks like a coral sting or maybe an injury from another. It isn't any of the external parasites.

 

[mandzhalas]

No corals in my tank, just rock. I do have kole tang there that could have nipped him

 

[vetteguy53081]

No corals in my tank, just rock. I do have kole tang there that could have nipped him

first thing I thought was tail strike or injury. Have you seen these two fish fuss with each other?
While this should heal on its own, appears to have redness. If it worsens, treatment will be seachem Kanaplex in a separate tank