Does my betta have fungus?

[cyg54]

Today I noticed a white spot on my beta's dorsal fin. I think it might be fungus but I'm not sure. He's in a 10 gallon heated tank with a sponge filter. I've had him for a year. The only thing that I can think of is that I recently added live plants to the tank that I bought online, so maybe something hitchhiked. The following water parameters were taken using the API Freshwater Master Kit:
Ph: 8.2
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: It's hard to tell but somewhere between 20-40ppm

 

[Colin_T]

It looks smooth in the pictures.
Does it appear to be fluffy or is it smooth?

It looks like a cysts on the vein (weird if it is) and there appears to be a build up of something in the fin, but behind the lump, towards the end of the fin. that may be normal but if it isn't then it will be related to the lump.

If it is fluffy then it is fungus.

If it's a cyst you could lift the fish out of the water and stab the cysts with a sterile needle to let the fluid out. Do this on a wet towel so the stuff doesn't drip back into the tank. Then apply a drop of broad spectrum medication to the site.

Methylene Blue is the best medication to use for direct application on a wound. You add 1 drop to the wound, wait 20 seconds, then put the fish back in the tank.

You could try applying Methylene Blue to the site first for a few days and if it hasn't improved then lance the bubble.

 

[cyg54]

Its definitely smooth. The best way I can describe it is that it looks like a corydora egg.

 

[Colin_T]

If it's smooth then it's probably a cyst or blister. You can try adding a drop of medication to the area twice a day for a few days and see if it helps. Otherwise I would carefully poke it with a sterile needle and see what happens. If fluid comes out after you stab it, then it is a cyst. If it is hard then it could be a calcium deposit or tumour.