Fungus is almost unheard of in SW fish. Most likely the "funky black marks" are secondary infections developing from where the flukes had left bite marks.
Although, I'm just now realizing that is a (juvenile) Chocolate Tang and the body color will darken as he matures.
Yea, I've never seen one transition before but I thought the color change would be more of an all-over darkening and not just patches on one side... but maybe it's just "extra" pigment there . I have no idea [emoji848]
Do you think maybe adding in the furan-2 would be beneficial for the wound on the gill? Or just give it another day in the current meds to see if it continues to look better?