Fin rot? Is it... fixed?

[Kat_Rigel]

Got 4 platies last week from my LFS and noticed some white discoloration and missing a bit of tail fin on one. I suspect fin rot from stress- do you guys agree? I went ahead and applied erythromycin per package directions (daily for 4 days, 30% water change on day 3 prior to med addition.) I also applied the recommended dose of Ich-X for 4 days since we know fungus and bacteria often go hand in hand. (Although I did not do as many water changes as it recommended; just 30% on day 3.)

I'm just kind of wondering how I know if the issue is fixed. I never saw any other symptoms like lethargy, for example. All 4 of the platies are quite active and appear to be happy. The appearance of the fin looks exactly the same. I am wondering if it was already starting to repair itself once it was out of whatever gross shipping water brought it to my LFS.

Also, I should probably start the quarantine timer timer again, right? (Personally I like to QT for 4 weeks. I had a bad experience previously and like to play it super safe.)

Thoughts? Tough to get a pic, so I took a short video. Please excuse the dangly fish poo. 💩 (I never thought I'd be embarrassed of my fishes' poo lol)

 

[Colu]

Looks like fin rot to me it difficult to tell it could be starting to heal I would Qarantine just to be on the safe and treat with aquarium salt 1 table spoon for 3 gallons