Hi have had this fish for like 4 years...aboutva year or 2 ago he developed this same skin irritation. I figured out my salinity was sky high corrected it and he was fine.... recently I redid my tank....bought all new live rock from KP Aquatics and he was fine....The last 3 weeks or so same thing came back....its not rich or velvet as far as I can tell... I checked my salinity and it was off a little 1.029 os so. had bad calibration fluid for refrac....just bought a new digital meter...anyhow....he eats jus no clue what it is....looks like a mucus problem... I have looked all around for metal in the tank and nothing...thanks