It sounds like a fungal growth. can you tell us more about your tank?
What size is your tank? Between 15 to 25GAL.
What temperature is your tank? 77.7
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? Yes, air stones.
Is your tank heated? Yes.
What tank mates does your betta fish live with? 2 Tetra, 1 Molly, 1 Algea eater, 4 guppies, and 2 loach suckers.
What type of food do you feed your betta fish? Nutrafin Max, tropical fish flakes.
How often do you feed your betta fish? once in the morning, and once at night.
How often do you perform a water change? I do a 50% water change every week
What percentage of the water do you change when you perform a water change? 25 to 50%
What type of additives do you add to the water when you perform a water change? Nutrafin cycle supplement, about 5mL
Have you tested your water? If so, what are the following parameters?
Nitrate: 20-40 (always stays constant, last test was 20 so it has come down)
pH: approx. 7.5
Symptoms and Treatment
How has your betta fish's appearance changed? Just the white fluff on it's fin.
How has your betta fish's behavior changed? Just when it happened he swims differently..
When did you start noticing the symptoms? just yesterday, he was perfect when I went to work and like this when I got off work.
Have you started treating your fish? If so, how? He is in his own bowl now with a tiny bit of Nutrafin cycle for medicating.
Does your fish have any history of being ill? No.
How old is your fish (approximately)? I've had him maybe two months.
Sorry I couldn't answer them all.