Testing with velvet?

[WilliamH2529]

Hey guys so I had a velvet out break in July and since then my tank has sat empty of fish and I plan to keep it empty until the end of September to be fully safe. But I have a question of when adding fish I don’t want to add them all at once and then they all get velvet again even though I’ve quarantined my fish this time and prior medicated them if I want to add one test fish how long should I wait to see if it develops velvet before calling it coast clear for the others?

 

[Lost in the Sauce]

I waited to day 76.

 

[WilliamH2529]

I waited to day 76.

No no what I’m asking is once the fallow period is done which should be about 90 days for me so possibly overkill, let’s say I add one fish a fire fish for example how many days should I wait to observe it to see if it contracts ich before I add the other fish? I want to sort of use one fish as a possible sacrifice