is my betta fish sick?

[Deadpool]

My veiltail betta fish, Deadpool, has been acting quite weird in the past couple days. It's almost as if he seems like he's under the weather. He doesn't move around as much as he usually does. And he's always hanging up on top of the tank between the filter and he heater. He used to do that occasionally, but now he's up there like all the time. And he has a weird looking thing on his bottom fin. Idk like if it's like a tiny white spot, or a hole. I can't tell.

idk really about ph levels in my tank or any of that kind of stuff :(

[Canuck Fins]

More information about your tank would help. How big is his tank? Heated? Cycled? Have you tested the water for ammonia/nitrates/nitrites? How often do you change the water?

[iheartmybettas]

Please fill this out. It will give everyone the info needed to help you!

Housing
What size is your tank?
What temperature is your tank?
Does your tank have a filter?
Does your tank have an air stone or other type of aeration?
Is your tank heated?
What tank mates does your betta fish live with?

Food
What type of food do you feed your betta fish?
How often do you feed your betta fish?

Maintenance
How often do you perform a water change?
What percentage of the water do you change when you perform a water change?
What type of additives do you add to the water when you perform a water change?

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed?
How has your betta fish's behavior changed?
When did you start noticing the symptoms?
Have you started treating your fish? If so, how?
Does your fish have any history of being ill?
How old is your fish (approximately)?

[Deadpool]

the temperature is right around where it always is, 75-76.5

[roadrunner]

he is probably cold and also current from the filter may be too strong for him so he found himself a spot that has warmer water and less water movement
if he has something on the bottom fin, it's a probably a sign of fin rot, you may want to start treatment so it doesn't get worse. Photos would help