That seems to be an abscess. I can’t say what caused it, but it is most likely bacterial. You won’t be able to easily treat it with external medication. I’d be inclined to say just wait and see, but since it is growing larger, there is some risk to doing that. At some point it will likely rupture. Do you have access to a treatment tank?Hi all! I noticed this bump on my tangs mouth when I it home from the LFS several weeks ago. It was just the initial bump at first, so I thought it might just have been trauma or a bite from another fish at the store, and decided to monitor. Tang is breathing fine, eating well, no flashing or scratching. But it does seem to have progressed up his face on his gill towards his eye now. Any ideas? Do I need to medicate?
Yes - if it ruptures. Not all abscesses are caused by bacteria, but after they rupture, they can all become infected with bacteria.
