blue tang with bruise

[trompet3]

My blue tang has been doing great. Today I noticed a blockish bruise on one side of his body. He is eating and swimming fine. Does anyone know if this is a disease or treatable?

 

[wolfeel]

Tangs have very small scales and bruise very easily. Another tankmate may have nibbled on him, or he may have hurt himself on equipment/rockwork. As long as the mark is black it will generally heal and go away...if there are any open sores or redness...you have an infection and he needs to be treated.
wolfie