Fungus on Severum fins?

Hello all!

I noticed a few months ago that my severum has some white spots that are identical on both sides of his fins (left and right on his side). I thought nothing if it, but it seems to have grown in size. One side is more on the fin while the other one is floppy. I’ll try to post a picture. Hoping it’s not fungus I cannot tell if it is part of his fins or fungus.

All the water parameters are good I do a 30/40% water change weekly. I also have been adding the aquarium freshwater salt the last few months as I was adding my final fish but it is still there.

Also should add, none of the other fish have anything similar, which is an Acara, group of rainbows, and group of polar blue parrot convict

Exact water parameters
Ammonia: .05 (doing water change tomorrow)
Nitrate: 0
Nitrite: 0
Ph: around 7.2
Temp: 72 (furthest from 2 heaters set at 78)
I cannot remember my exact hardness for my water as I tested a while ago, but it is soft.