What size is your tank? 13 liters about 3.5 gallons
What temperature is your tank? 26 Celcius
Does your tank have a filter? no
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? none
What type of food do you feed your betta fish? flakes, seem good
How often do you feed your betta fish? everyday, fast one Saturdays
How often do you perform a water change? twice a week
What percentage of the water do you change when you perform a water change? one 50% one 100%
What type of additives do you add to the water when you perform a water change? conditioner
Have you tested your water? If so, what are the following parameters? no
Symptoms and Treatment
How has your betta fish's appearance changed? 0.5mm edge of fins becoming white, and also some edges are "weaker"
How has your betta fish's behavior changed? yesterday, he opened his mouth a lot inside the water, he opened his fins as if he was seeing another betta.
When did you start noticing the symptoms? a week ago, when i got him.
Have you started treating your fish? If so, how? no
Does your fish have any history of being ill? no
How old is your fish (approximately)? 0.5-1 year
I posted pictures of him there, he's the same.