Need help Diagnosing/ Treating my betta

My betta has a little white fuzz on the tip of his tail. He is a Crown tail so it’s only on the tip of one strand. His tank is 4 gallons filtered and cycled, but two days ago there was a little Biofilm breakout so I cleaned all his decorations and did a 50% water change and all the levels are sitting at:
Ammonia: 0ppm
Nitrites: 0ppm
Nitrates: 25ppm
His tank has an Indian Almond leaf in it.
I have attached a picture and I circled the spot in question, it looks like a spot on the glass I know but trust me is isn’t .
I want to say it’s cotton fish fungus at its beginning stages but it’s ONLY on his tail. And the reason I’m questioning myself is because my roommate said it may just be a piece of biofilm that got stuck to him..... (I’m not sure that’s a real thing, but it made my question treating him immediately. I may be a little dumb). I am also wondering if Aquarium salt can be used to treat the fungus as I’ve had wonderful results treating my other bettas with it.
Thank you!!!!!!

 

I can sort of see it, but Fishlore won't let me zoom in that much. Can you maybe take a close up picture?

 

I can sort of see it, but Fishlore won't let me zoom in that much. Can you maybe take a close up picture?

I tried to get in close, sorry he just wiggles around so much

 

Its hard to tell but it may be fungal from what you're describing. Fungal infections are brought on by poor water quality and he seems to have some pretty damaged fins. I Do you know your recent water parameters?, how often are you doing water changes?

 

He current water perimeters as of an hour ago were:
Ammonia:0ppm
Nitrites: 0ppm
Nitrates: 25ppm
I change about 30% of his water weekly and treat it with slime coat plus.
his fins have looked like that since the day I rescued him...... I got him at a local pet store.... apparently he had been brought in because the owner didn’t want him anymore, I felt so badly that I just had to take him in. I was hoping the slime coat plus would help regrow some of his tail but it hasn’t really done anything

 

I can see it clearly now; I think all bettas are get the wiggles when they see a camera. It looks like something is attached, although I'm not sure if it's biofilm or a fungus growth. Try to entice him to jump out of the water a bit with some food. If it is biofilm, it might get knocked off.

 

I would add conditioned Tannin extract straight to the tank. The IALs take forever to deteriorate and they slowly release tannin. Theres a better effect if the tannin is more concentrated. Tannin has natural antibacterial properties and helps with fin growth.

I would increase water changes and dose a medication like API Body & Fin cure or Furan-2.

 

Okay!!!
would you happen to know where I can get some tannin extract? I am from Canada so Furan-2 and API Body and Fin cure are hard to come by.... I checked online and the earliest I can get it is July 23rd, so do you happen to know another menthol that I may be able to get my hands on faster?

 

Okay!!!
would you happen to know where I can get some tannin extract? I am from Canada so Furan-2 and API Body and Fin cure are hard to come by.... I checked online and the earliest I can get it is July 23rd, so do you happen to know another menthol that I may be able to get my hands on faster?

You get Tannin extract from boiling many IALs/Cattapa leaves for many hours. You can also use 100% all natural Rooibos tea that can be found in grocery stores or online. Its made of 100% crushed dried Redbush leaves, make sure you get the teabags that are 100% Roobios, caffeine free and no additional additives . The teabags happen to leech a very concentrated amount of Tannin rather than the leaves. I use both IALs and Roobios tea though