There are several options you can go with, collected, long fight or nuclear.
Myco is not something to mess with if you have a compromised immune system, and you stand little chance of being infected if you have a normal or above normal immune system.
Dianna Walstead showed that a confirmed case of Myco. can be beat. Mycobacterium exists in every water system. It competes with other bacteria, and readily looses since it is a very slow growing bacteria. When the tank is out of balance and the normal bacteria is not in the numbers required to keep the competition high Myco can spread. Giving the normal bacteria a good home to grow in can suppress the Myco again. Make sure if you go the long route you get a UV. that is capable of handling bacteria. most of the cheapies out there are good for algae, and that's really about it. I would follow exactly Dianna Walstead's method for fighting this, you could have the same results. Run the UV. Don't spend as much time cleaning out the tank, and as soon as ANY fish shows any signs or distress catch and euthanize them. As Dianna found out her other Rainbows (which are prone to this) never contracted Myco even though they were in the same tank for a very long time. She even had one she thought might have been infected necropsied and it turned out it had something else. There are quite a few strains of Myco. that exist in natural waters (even tap) and determining which one it is can be a problem.
The other option is to Euthanize all your fish, and methodically disinfect EVERY item that has come in contact with that tank with a very high concentration of chlorine, I think it has to soak for a min. of 30 min. to be effective. All of your plants, hardscape etc will need to be discarded.
