Blue Green Chromis has a possible bacterial infection

[claireputput]

How can I treat a blue green chromis that appears to have what looks like to me a bacterial infection. It is a patch on his side that seems lighter in color-about a quarter inch almost square.
It is eating okay and swimming fine but this is a place that was not there yesterday.
He has been in the dt for over 6 weeks and never once showed any signs. No other fish has any signs of a problem.
Even this one only has what appears to me as a raised light area but no other symptoms-should I be worried?

 

[Sk8r]

Is that the only chromis? Sometimes they'll start fighting among themselves over spaces in the rocks at night, and they will sometimes attack in that pattern. If it were reddened I'd say look for a mantis or suspect a rabbit, but it could be aggression from another fish.

 

[claireputput]

I have four of the chromis and that is probably what is going on-I will try and see if I catch him/them attacking. It is not read at all. btw.

 

[HumbleFish]

Post a pic if you can. Chromis are often susceptible to a disease called Uronema marinum.

 

[snorvich]

I have four of the chromis and that is probably what is going on-I will try and see if I catch him/them attacking. It is not read at all. btw.

Four chromis will become one over time as the most aggressive winnows down the herd. Since chromis are highly susceptible to uronema, please post a picture so we can advise appropriately.

 

[claireputput]

Four chromis will become one over time as the most aggressive winnows down the herd. Since chromis are highly susceptible to uronema, please post a picture so we can advise appropriately.

I will post a picture tonight when I get home although it has not changed-not bigger or smaller.