Fuzzy white behind fins. Cotton fin fungus?

[unclepancake]

I was about to go to bed and checked on my new guy yasha goby alone in his own tank and noticed 2 white fuzzy things behind his fins. I noticed him trying to scrapes it off by rubbing on the rocks. From a brief search it looks like cotton fin fungus? I pocked him up around 4p from lfs and did not notice it when i left. Pic should be attached. Thanks in advance.

 

[Sawdonkey]

It actually looks like fiber. Are you sure it’s not? Do you have filter socks? Looks like fuzz from filter socks.

 

[unclepancake]

No filter socks for this tank. I've been trying to catch him but I think he's been enough already. I will try to remove it from him manually in the morning.