I recently purchased a Flagfin. Over the last few weeks the Flagfin has brightened up in colors and acted much healthier. This last week, I noticed a red coloration on the gill plate and a slight reddish hue to his head. Is this a disease or a natural coloration? See images below.
Looks normal.Looks like you are seeing the redness underneath because of the transluscence in that area of the fish.Like the redness you see from the gills of a blushing angel showing through because of the transluscense of the gill plate.