What is on my bettas fin?

Hi all,

My betta has been moved to a quarantine tank to handle fin rot and he also has this file of white stuff on his fins. Could anyone help me as to what it is and how to get rid of it? He's currently in a 3 gallon tank kept 78-79 and the parameters are: pH: 7.2, Ammonia: 0, Nitrite: 0 Nitrate: 5-10.
Thank you!

 

Is it white on the just edges? He might have a bit of fin rot.

 

Is it white on the just edges? He might have a bit of fin rot.

Yeah, it's just white around the edges.

 

Yeah, it's just white around the edges.

Probably fin rot then. Increase water changes to 25% every other day and it should go away after a while.

 

It's either bacterial or fungal.