I recently got a beautiful veil tail Betta who I unfortunately noticed has fin rot. We spoke to the aquatics place I got him from and got our water tested and everything was perfect, leading us to believe he had it when we bought him. His fin rot looked quite severe to me as I woke up on morning and he had lost quite a bit of his tail.
The shop recommended to me Myxazin in which I gave him the correct dosage for 5 days. He appeared to be improving. I was a bit apprehensive to take the carbon filter out as really I didn't want to ruin the water quality of my tank, but did as I was aware the Myxazin wouldn't work otherwise. The plants in my tank and a bit of the side of my tank has brown marks on which I'm presuming is from the Myxazin but it seems easy to remove. After the five days I waited a few more to put the carbon filter back in and do a water change.
All was going well until I woke up yesterday morning to my Betta's tail being gone again, however this time it was much worse, and even a bit of his top fin was on the bottom of the tank. I panicked and have started him on the Myxazin again, and though there are signs of improvement, I'm worried that if I stop the treatment and do a water change after 5 days and put the filter cartridges back in he will just deteriorate again.