Sorry for your loss, you did the best you could........... but its weird I have had the same thing with one of my blood fin tetras, but it has been at the base of his tail on his body, can you get fin rot on a body?????? I have treated him twice with maroxy as it seemed to come back as soon as I stopped treating him the first time. Having just finished the 5th day of treatment I am about to do a 50% water change etc etc, however the growth has not gone down...............should I go get the marycyn 1 2 or maybe try with garlic baths????? What do you think would be best????????