I have had Marlin for almost two years. He is in a 2.5 gallon tank which is held constant around 80 F. I change the water 50% every other day and 100% every third change.
He developed fin rot a couple months ago (I did not change the water as often back then) and it seemed to go dormant for for a while. But for the past maybe six weeks his tail has been shredding. It will get really bad one day then for a few weeks heal and look almost normal, then within one day it will go back to looking very shredded. I believe it is fin rot, but it doesn't have a noticeable black color like fin rot is known to have.
To treat it I have been using API treatment for fin rot and API stress coat for the past month. I don't know what else I can do but I want this problem to go away! Any suggestions?