i have a 2" long fresh water angel. he has some perty severe fin rot his top dorsal fin has become two separate fins! i am hesitent to add a fungus and bacteria medication because my tank is perty new and i dont want to add medication that will hinder the bio-filtration process. non of my other fish show any signs of it. will the fin rot naturaly go away with some time or is this a something that has to be treated?