I thought my Betta had fin rot, but there was only discoloration and a fraying of the ends. I put him in a new, clean tank treated with aquarium salt with daily water changes. Seemed to help but no new growth. Today his gills are slightly discolored. He is eating normally and active, but no bubble nests. He's in a 2.5-gallon tank, unfiltered with live plants. I've been doing 100% changes twice a week. All his water parameters are in safe ranges?
I think you are doing the right thing now. You just need someone who knows about Bettas, like a veterinarian, to check your water parameters and advise accordingly.
Updated on April 5, 2018
By Januaris Saint Fores