I always say, "may coat the labyrinth organ". I have seen fish with simple cases of fin rot die at my store after the use of bettafix. Now, to be fair, I did not dose it. I can't prove it was the betta fix (or even if it was used properly), but I prefer to be safe rather than sorry. Especially, when I have stockpiled almost all useful antibiotics.
The mom of: Too many to list now.