Royal Gramma with weird blister.

[Luukosian]

Had this Royal Gramma for a long time(5 years+) and just noticed today at feeding time it has almost what looks like a small blister but it's a semi-transparent white color. All other fish fine and no recent additions. 90 gal mixed reef other fish are foxface, blue damsel, eyelash goby, bangaii cardinal and all are fine. Inverts are a coral banded shrimp, pencil urchin, various snails. Pictures are under LED, tried to tweak the levels but still really blue so this is the best I could do. Swimming and eating fine. Any ideas? Almost looks like just a scale is infected or something. It's right before his purple turns in to yellow in the pictures.

 

[Oxylebius]

It could have gotten too close to a coral and got stung. If this is the case it will go away in a couple of days on its own (w/good water quality). If it gets worse or infected, you may want to place it in QT and treat w/bacterial meds.