I received this message from a "specialist at a large aquarium" after looking at the images below. My questions are how do you debride a fish?
I’m still not sure how I would handle this one. It does not look like lymphocystis. It doesn’t really look like copepods either. Generally any tumor like growth would be more solid and not have random protrusions like this fish has. What I can tell is that the fish is thin, probably not eating well because of the mess going on with its mouth. It looks like there may be a few ich spots popping up on its fins and sides, but that would not be abnormal for a stressed fish. You know the one thing that may be possible is mycobacteria lesions… but then I wouldn’t expect them to extend out as far as these appear to.
bottom line is if I had this fish here I would debride all the white areas and really try to clean the area up, then give the fish a peroxide dip and put it into prolonged hypo treatment. Chloroquin probably wouldn’t hurt either.