Originally Posted by
Paul Sabucchi
The advice Al has given is born from a lot of experience, we have all incoured in mishaps and had to learn the hard way that mother nature does not necessarily follow our human logic. Although it is apparent that you are dealing with some kind of pathogen short of employing the services of the pathologist recommended by Al you will not know if it is viral or bacterial, and if the latter is it some kind of mycobacteria that can stay dormant for a very long time and resist to most antiseptics or could it be a species of bacteria that produces spores?
As extreme as it may seem the only surefire way to be reasonably sure to have left the problem behind is to start with a clean slate. If you want to keep the suspected carriers again the advice given by Al (in the video that Joey put on YouTube) to keep that tank in a different room as far as possible from the other fish with separate equipment and taking sensible measures to avoid cross contamination would be the best way to go.
When I was at college the infectious diseases department was divided in 2 separate units, bacteriology was on the 2nd floor and virology in the basement. This was done after one too many times a bug got inadvertently carried and infected/destroyed the cell cultures used for viruses, and we were all professionals with an understanding of what was at stake