Finless Bettas?!?

[CharStarr]

Hey everyone, so my mom has two female bettas both housed seperately in 2.5 gallon tanks. When we went to feed them yesterday we noticed that Delphina's fins were completely gone, her color was paler and she was a bit bloated. Patsy has started to go the same way except right now her fins are just shorter, she doesnt have the other symptoms yet. Does anyone know what' going on here? We do regular water changes. Thanks in advance.

[CharStarr]

Housing
What size is your tank? 2.5 gallons
What temperature is your tank? 75 degrees F
Does your tank have a filter? No
Does your tank have an air stone or other type of aeration? No
Is your tank heated? No.
What tank mates does your betta fish live with? None, they are both alone in their tanks.

Food
What type of food do you feed your betta fish? Betta pellets.
How often do you feed your betta fish? 3 a day.

Maintenance
How often do you perform a water change? Every three to four days.
What percentage of the water do you change when you perform a water change? 100%
What type of additives do you add to the water when you perform a water change? AquaSafe and Conditioner.

Water Parameters:
Have you tested your water? If so, what are the following parameters?
I only have a nitrite test and an ammonia test.

Ammonia: <1 ppm
Nitrite: 0 ppm
Nitrate: N/A
pH: N/A
Hardness: N/A
Alkalinity: N/A

Symptoms and Treatment
How has your betta fish's appearance changed? Delphina's fins are completely gone, she's paler and bloated. Patsy's fins have started to shorten.
How has your betta fish's behavior changed? They haven't especially Delphina she's still trying to jump and swim.
When did you start noticing the symptoms? Yesterday.
Have you started treating your fish? If so, how? Not yet.
Does your fish have any history of being ill? No.
How old is your fish (approximately)? Not quite sure, we purchased them about 6 months ago, they don't look to be over two years old.

[Sivan]

Ok.

1. 75 degrees to way too cold for betta fish. The absolute coldest they should be in is 76 degrees but your goal should keep the temperature at 78 to 82 degrees.

2. If the fish is bloated, fast it for a day to see if the swelling goes down. Does she have any appetite or interest in food at all?

3. Please post a picture so we can see how bad the damage is. If fins vanish to a certain point, they will not recover. Did you see any dark outline around the fins in the past? Any black coloring?

It sounds to me that the fish is suffering from fin rot/melt and some other issues. A picture would greatly help, though.