Hey, noticed Oscar has some grey something on his sides and brown something on his top, he behaves normal from all aspects but has that on him.
No idea what it is but I can rule out Itch, any kind of worms, and it doesn't look fuzzy.
I took some bad pictures(sorry Iphone and he wasn't really up for being photoed)
What size is your tank? 10g
What temperature is your tank? 82f
Does your tank have a filter? yes
Does your tank have an air stone or other type of aeration? no
Is your tank heated? yes
What tank mates does your betta fish live with? 2 apple snails
What type of food do you feed your betta fish? Frozen dried Blooworms, Brine shrimp, Grains(no idea what company don't have the original container), JBL nano betta
How often do you feed your betta fish? twice a day(small doses), 1 day a week fasting
How often do you perform a water change? Once a week
What percentage of the water do you change when you perform a water change? 25%
What type of additives do you add to the water when you perform a water change? Prime, once a month I add Sachem Stability
Have you tested your water? If so, what are the following parameters? Didn't test for a few days but last time I did all was good(few days), changed his water today.
Symptoms and Treatment
How has your betta fish's appearance changed? Browish something on the top, mainly the head, something grey on the side
How has your betta fish's behavior changed? Didn't change
When did you start noticing the symptoms? 10 min ago noticed its gotten bigger but noticed first time he had something on him yesterday or two days ago..
Have you started treating your fish? If so, how? Didn't yet because I have no idea if its something or just got something stuck to him
Does your fish have any history of being ill? Yes very... Chronic tail rot, he's a tail biter, had Anchor worms, a fungus on his head, Columnaris(had all of those together when I got him fun fun) He recovered from his last finrot about a week and a half ago..
How old is your fish (approximately)? around 5-6 months, got him aprox 2.5 months old