This is very important information that needs to be circulated BUT there are a few caveats that I want to add.
First, the majority of people on the forum don't have fish rooms or extensive (and expensive) breeding operations. For these people, the risk of contagion between fish is obviously minimal, especially if they have just the one fish.
Secondly, without the same necropsy/autopsy tests and tissue samples, it is impossible to know what a sick fish at a pet store may have. Saying that is has mycobacterium without these tests is irresponsible.* Many people have purchased sick fish and successfully nursed them back to health, myself included. I think a lot of people would agree that many of the sick fish at a pet store are suffering from poor water conditions, not myco. Therefore, I won't condone discouraging people from buying sick fish if they want to attempt to nurse them back to health. The people who do this do so knowing full-well the fish is sick and knowing full-well it may die. The vast majority of people are not ignorantly buying sick fish. As long as people practice sanitary fishkeeping and avoid contamination, go for it.
Thirdly, this needs to be made clear: mycobacteria is the same bacteria that causes fish tuberculosis. HOWEVER, just because a fish is diagnosed with mycobacteria doesn't mean the fish has fish TB. The fish we have seen on the forum who have been affected do not exhibit the same symptoms as TB.
Now that I've said that, again I want to say the information included is informative and well-put.
* Strictly speaking, yes, every fish has some small amount of mycobacterium, just as every fish has some small amount of every bacteria present. What I'm referring to is a potentially lethal outbreak of myco.
The problem is we CURRENTLY have a strain that is VERY in the betta fish population. I saw it in petco and petsmart in several locations where I live. I watched it move though my fish room. It needs to be destroyed. It is VERY difficult to have it over here and keep it from getting over there.
If you see the lesions you probably have m. triplex. If you have the fuzz and it doe not respond to columnaris type meds.. again.. mycos. You can go blindly down a path that MAY be destructive or you may actually take some precautions.
Again.. if you have it.. it will live on your counters where you set your net, in your drains where you dump water.. in your tanks, gravel, snails.. I had mystery snails that just died for no reason. Cut them open and guess what... mycos granulomas. And if a sick fish in a cup is worth the risk.. knock your socks off. But for some this ACCURATE information will be heeded and they will reduce exposure or get rid of the crap. Even if one fish.. and it has mycos.. they still have it when they get the new fish without proper chemical to kill the stuff. Guess they can just use vinegar. Wonder why the scientist did not think of cleaning with vinegar and just adding some salt to the water.