Discolored head in peacock goby- a bacterial disease?

Hi, one of my peacock goby's head has a white discoloration. It doesn't worry me so much but I just wanted to make sure its not a disease or anything. It's kind of hard to describe, but its a pale white coloration of the head of the fish and extends a little to the dorsal fin. It doesn't have a slimy or odd texture but its sort of spotted with the fishes normal purplish color and the white color with the white color being the majority. All of the other fish are fine, but this goby does seem sort of listless, but then again he's pretty new so that might be he's stressed and still adjusting to new surroundings... I might try to get some pics later today.

Do you guys think it might be some sort of bacterial infection? If so, what meds might help?

Thanks!