i also have had this problem since up grading tanks i'm putting it down to his bolt hole been down the side of a rock where he also lays on the sand so either muck particle or air bubbles as i`ve up graded my tank & lights & i'm getting air bubbles everywhere on rock sand etc i`ve had this problem around 4-6 weeks now so if it is ich/white spot its not causing a problem as he is no different nor are any other fish within the tank but i`ve read about ich/white spot plus had it a few times & ich spots don`t really move around that fast normally 2-4days etc strange how its a firefish thats getting this problem......