| You have had so many suggestions that I am almost afraid to say anything.....
Anchor worms usually attach to a scaled area instead of the fins. Some of the photos look like Argulus (fish lice) sores and the infection that typically follows an Argulus bite. The anchor worm treatment will also kill Argulus, but you still have to deal with the infection.
Bacterial infections that follow a parasite bite will often heal more rapidly and with less intervention than infections that occur spontaneously. Perhaps this is because a spontaneous infection signals a weak immune system and/or poor water quality.
-ste |