White stripe on goldfish fin, fraying...not sure what this is

[ultros]

Hi all,

I have two goldfish currently, and one of them recently had a part of their fin turn a whitish color. I've heard about fin rot but from what I understand, that begins at the edges of the fin and works downward toward the body. This discoloration happened from the bottom up. Recently, the top of the fin started fraying. I do not see anything strange about the fish's behavior or notice anything different besides that white stripe on his fin. It does appear that the base of the fin where the white stripe begins is a little swollen.

I've been staying on top of the water changes, and my latest water test (a few days ago) showed that all parameters were good. Really not sure what this is, would appreciate any input.

Thank you

[TheSwissAquarist]

Could be fun rot? @Colu

[Colu]

I would add some aquarium salt 1 table for 2 gallons for one week it looks like a deformed fin ray  looks like a lump at the base of  the fin ray if you notice it getting worse after 5 days than I would do a course of maracyn2 in food active ingredient minocycline has anti-inflammatory properties 

Edited January 2 by Colu

[ultros]

Thanks for your input guys. I will try the aquarium salt first...any idea how this happened? I guess it was pretty surprising. I've always checked the water parameters regularly in addition to weekly 25% water changes.