Aaack Fin Rot!

[Elaina]

Since I've moved Frosty, Rhett, and Mugsy into the 10 gal divided tank, both Frosty and Rhett have developed fin rot. Rhett's doesn't look too bad, but Frosty's just looks awful. He had such a gorgeous full delta tail before and he's looking like a crowntail now .
I've started doing salt baths yesterday(and continued them today), and did a complete water change yesterday. It looks like it has gotten worse today, so I'm hoping the salt baths will start doing their jobs soon...

[PetsGalore]

aww poor guy. hopefully the baths work and he gets better. good luck!

[BakaMandy]

Personally, I'd suggest treating them both in separate hospital tanks, not only would it help prevent reinfection but make it easier to change their water since you need to keep it as clean as possible.

I've also noticed turning off the lights help, since sometimes while betta fish are sick they can become more stressed out. Turning off any direct lights will help reduces stress.

And Frosty looks pretty serious, I don't know if salt baths will actually help him. If you see no improvement within 2-3 days, immediately switch to medicine.

I'd recommend Maracyn+Maracyn-two mixture. Take about 20tsp of water in a small resealable container and add one package of each to the water and mix it together until they are both dissolved in the water. Use 1tsp per gallon to treat him every day. Make sure to stir the mixture every time before you dose.

The suggested period of treatment is 5 days, but some people recommend treating for 10 days to make sure the fin rot is completely cured, especially in a nasty case. Otherwise you may have to do multiple seperate treatments and that may drag on through a long period of time, reducing your fish's resistance to the disease.