I know none of this is encouraging, and it is a painful lesson for you, and any and all aquarists in why we need quarantine tanks.
Now, you will probably need to sterilize the entire display tank, starting over any cycle that has been done, because the bleach will kill, and needs to kill everything to prevent the disease from killing any fish you put in the tank next. Any beneficial bacteria you have grown during your initial cycle will be gone, as they are much more sensitive than the pathogenetic columnarus.
Now, you will probably need to sterilize the entire display tank, starting over any cycle that has been done, because the bleach will kill, and needs to kill everything to prevent the disease from killing any fish you put in the tank next. Any beneficial bacteria you have grown during your initial cycle will be gone, as they are much more sensitive than the pathogenetic columnarus.