I've had a school of 6 chromides in a 37 gal bowfront for several months now and recently (the past month or so) one in particular has been slowly losing its color. All my parameters are fine and don't worry they are in brackish water (1.008). While he doesn't seem sick (not lethargic or breathing heavily) his color continues to fade. Is this something I can fix or cure or is he just a weird fishy?