4-5 months of one growing white spot

[MorganJayne]

Hi everyone! I was looking for some fish advice on my Opal Male betta, Kodak. He is about 5-6 months old, and when I got him, he had a very tiny white spot on his body. Although, since I got him, it has been growing (very very slowly). It started as a grain of salt, but now it is about the size of half a pea. I have been scouring the internet for figuring out what this might be and how to treat it. However, I can't grasp what exactly it is since it is only on one spot on his body. I am almost positive it is a fungal infection, but I want to double check with any help/advice from here to make sure I am going to treat the right thing for Kodak. 

He is energetic, but not as much since I got him. He likes to rub himself on the decorative plants I have in the tank. I also noticed he is becoming more lethargic lately, and has himself stay in place most of the time by mostly resting in the parts of the tank that have little current, like inside of his pink rock. I appreciate any advice and/or help to what this could be and how I should proceed. 

I checked the levels today after a partial water change yesterday:

pH: 7.1

Nitrates: 13 ppm

Hardness: 82 ppm

Nitrite: 0.75 ppb

Ammonia: 0

KH/Buffer: 7 dKH

Water Temperature: 79F

I have attached a clear picture of the growing spot, and it is now beginning to grow outward. Before that, it was flat and had no texture. It has only begun to grow outward from his body in the past couple of weeks.

Both pictures are from today, for one he is in the light and the other is the shadow of it which clearly shows its shape. Thank you.

[Colu]

I would do a daily water changes  and add a double dose of prime every 24hr till your nitrites constantly stays at zero any nitrite is harmful to your fish it doesn't look like a fungal infection bettas are heavily inbreed they are prone to developing tumors or benign growths that what I think this is as it been slowly getting bigger over 6 months if you don't have live plants I would add some aquarium salt 1 table spoon for 3 gallons for two week just remember to only put back in the amount of salt you take out so if you do a 3 gallon water change put one table spoon of salt back in I would also add some Indian almond leaves as they have antibacterial and antifungal properties depending on the quality of the leaves you might have to add one leaf per gallon to get a beneficial effect  and update in one weeks time @MorganJayne

[MorganJayne]

Thank you so much for the information. I will do daily water changes and keep checking the nitrites as well as priming with double dose. I do have one live plant (a banana plant) that I recently added to his tank so I will skip the aquarium salt, but if I don't see any improvements I can take it out. I will get some Indian almond leaves though. Again, thank you so much, I will update in a week! @Colu