Not sure what the H E Double-Hockey-Sticks this is, but it's aggressive so time is of the essence here. It looks to me like some form of Ich that is eating her slime coat and spreading rapidly.
She was just bred, so the housing situation is rather complicated. I want to know whether I should answer this according to where she is normally, or where she has been over the last few days.
Before anyone bites my head off: the low water level is for her own good. The water she was in when I found her was only an inch (maybe an inch and a half) deeper than this and she was making a lot of trips to the surface--not to mention having a hard time doing it.
Before anyone tries to bite my head off again: the container in the picture is a quarantine bubble, not her normal home.
Housing I will answer this one when someone tells me which one to apply: see above
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?
What type of food do you feed your betta fish? Frozen Blood Worms and Hikari pellets (they're the best we have access to in town)
How often do you feed your betta fish? Once a day
How often do you perform a water change? The schedule varied in this case due to her other situation. Will explain in the "medical history"
What percentage of the water do you change when you perform a water change? See above
What type of additives do you add to the water when you perform a water change? Prime water conditioner
Water Parameters: Not recently. See "symptoms and treatment"
Have you tested your water? If so, what are the following parameters?
Symptoms and Treatment
How has your betta fish's appearance changed?
Covered in a white rash that is fairly uniformly distributed over her body, gills, mouth, eyes and pectoral fins.
Presence of a sort of gauzy layer that may be slime coat.
How has your betta fish's behavior changed?
Lethargic, having difficulty getting to the surface to breathe.
When did you start noticing the symptoms?
2 hours ago. Began treatment immediately.
Have you started treating your fish? If so, how?
Immediately placed in sterilized quarantine
Aged water (allowed to rest for 24 hours after conditioning) + potassium permanganate (Jungle Water Clear)-->We were told in another thread that KMnO4 kills things
Lowered water level to minimize effort to breathe
Placed in the dark to ease stress
Does your fish have any history of being ill?
Yes. Hence the complication: we were in the middle of treating her for a Columnaris infection when this hit. The colony was dead and I was about to give her the last dose of antibiotic when I found this.
Instructions for API T.C. Tetracycline state that the first two doses should be put in 24 hrs apart, then let another 24 hrs pass before doing a 25% water change and adding the 3rd dose. Dose #4 goes straight in, then a water change gets done when the full course is over on day 5.
Today would have been day 4, but this happened.
This is why her housing situation is difficult to explain, since she was in a different quarantine set-up for that course of treatment.
How old is your fish (approximately)? No more than 6 months.