Wow deja vu all over again....did I respond to this in a different thread the other day? If not, we have two identical cases going on(grin).
External marine fungal infections are almost unheard of. This could be a mild bacterial infection, but most likely just damaged fin rays. Using the pic as a guide, take new pics daily. If the spots come and go and show up in different locations, it’s a parasite . If they stay the same, it is just damaged fin rays,
Jay