Betta’s Ventral Fin Is Curled

My male blue veil tail bettas ventral fin is curled. It’s only one but I am concerned. I also noticed a bit of film on top of his water not much but it made me think of a bacterial problem. I took him out and now hers in the little cup I got from wal mart. Here’s info
Tank: 1 gallon glass bowl (I know he should be in bigger but space is limited)
Temperature: 72 degrees
Decorations: little cave and fake anemone
Can’t test water as I don’t have water tester but I saw it might be because of hard water
I know photo is bad but that was all I could get before he drove me crazy

 

Welcome to FishLore!
The film could be a sign of bad water quality, which can lead to fin problems. How often do you change the water and how much do you change? Also, 72 degrees is really cold for a betta. It should be at least 78.

 

I do 100% water changes ever Thursday

 

It kind of looks like fin melt to me, although it's hard to tell from the picture. Improving the water quality should help clear up the infection, though it may take a month or two for the fin to get back to normal.
I'd recommend upping your water changes to 75-100% twice a week. Tanks that small require a lot of maintenance compared to larger ones in order to keep the water quality in check.
It would be great if you could upgrade to a 2.5 gallon or larger with a heater and filter - you wouldn't have to do as much maintenance and would deal with illness less frequently. I've found that most betta's behaviour really changes for the better when they're upgraded to a larger tank, and for that reason I personally wouldn't keep a betta in a tank smaller than 5 gallons.
Best of luck with him!

 

Great thanks for info one more thing what’s fin melt

K changed his water and made sure it’s warmer thanks!

 

Good to hear, though you should try to keep the water temperature consistant when doing water changes as differences of more than a degree or so can stress the fish and the water will cool off rapidly anyways without a heater.
Fin melt is an infection that's similar to fin rot but makes the fins look kind of stuck together or clamped. It's not 100% clear what causes it, but there seems to be a link between it and bad water quality.

 

It's also common for crowntails to get a "twisted" part of their fin, which is what mine had when I purchased him.

 

I just got the Topfin Intrigue tank from Petsmart, its 2 gallon hexagon on sale for 19.99 I am using a very small stand for this particular tank, it does not require much room. I also have a 3 gallon aquaview round tank from walmart, I like this better but it requires more space as it is taller and wider! Bigger tanks are so much easier, my 15 gallon is stress free wish I had room for more large tanks! Good luck!