greying is also a sign of pecking order too in a large shoal. its a visual communication to state dominance amongst the group. angry clowns go very dark. some go dark due to other reasons . you have to watch them and study. ive got a solitary clown in one of my cichlid tanks. hes thriving in there and thinks its a cichlid now and competes for food in a way ive never seen before. starting to grow at an alarming rate. say an 1 inch per month.