My betta fish had fin rot about a month ago, losing nearly his entire bottom fin. His fins have been clamped ever since and his lost fin has not regrown despite a month of treatment with the bettafix medicine. It appeared that it was growing back for a time, his fins even started to relax a bit and he flared his gills at himself in a mirror but he has relapsed since then, his fins are clamped again and he will not flare at himself when I hold up a mirror. Any growth that was startd has stopped and he only has a little stub. This missing fin leads to strange swim patterns and as a result he just sits on the bottom of the tank and squeezes himself in between rocks at the bottom, only coming up for food and air and rarely swimming around.
Does anyone know of anything that might make his fin grow back or generally improve his condition? :( he seems like such a sad fish.
Incase it matters, I have a 2.5 gallon tank. I clean 50% of the rocks/clean the dirt from the bottom with a tube/change 25-50% of the water once every three days.