almost overnight my clown, and only fish in my 14G tank for weeks has developed black soot like hyperpigmentation all over his body-looks as if he was dropped through a chimney -uniform all over body- fish otherwise acts well, active , feeding well, SG 1.023, 75 degrees , 0 ammonia, 0 nitrates, 0 nitrates. Im sorry I dont have a picture - I will send one in when I get a chance-pigmentation appears to be within clown and not growing onn skin- any thoughts ?