First off this is a first time beta, sorry if you have seen a huge amount of these.
I am not the owner of this fish, it actually belongs to my girlfriend. I'm losing sleep over this so I couldnt wait to post.
Housing
What size is your tank? I believe its a 1 gallon
What temperature is your tank? pending
Does your tank have a filter? no
Does your tank have an air stone or other type of aeration? Open top, not sure what this means.
Is your tank heated? no
What tank mates does your betta fish live with? none
Food
What type of food do you feed your betta fish? Generic beta fish food, blood worms
How often do you feed your betta fish? 1 small pinch of beta fish food, or 2 blood worms
Maintenance
How often do you perform a water change? Was weekly, she didnt do it for some time, longest was 3 weeks at maximum.
What percentage of the water do you change when you perform a water change? was 80% weekly.
What type of additives do you add to the water when you perform a water change? water condintioner
Water Parameters:
Have you tested your water? If so, what are the following parameters?
No test yet. I know that the water has changed to spring water (not bottled) after visiting her parents.
Additional Information.
I noticed this acouple days ago, and I was like hey you really need to change your water. After the water was changed I noticed the tail of the fish looked like a clown tail. This was very scary to me because it was originally a moontail. I know that when she traveled she put the betta in a jar for safety. I am worried that this stressed the betta greatly.
I'm positive that it is finrot. If its biting its very severe. Just in case I decided to ask the experts. At this point I dont know how to treat it. If I should just have her use salts or go straight for the antibiotics.
Here is the before and after photo
Before:
After: