Alright, I’ve been doing this a while, but this one is new for me. This tailspot blenny has been living in my frag tank for about a year. Maybe 2 months ago I cleaned out the frag tank and moved him into another tank in my system which used to be a refugium but it now doubling as an overflow frag/holding tank. About two weeks ago he started losing color on his head. After maybe a week his head was completely white. Then a few days later he started losing color on his body. He now basically looks like a dead fish you would find laying at the bottom of the tank - but he is still acting completely fine. His skin is not sloughing off in sheets, there is no slime or visible decay, etc. Not lethargic, keeping balance well, hiding an appropriate amount, and still eating. I have moved him to a quarantine tank and am hitting him with metroplex, kanaplex, and furan-2.