Planted Tank Enthusiast
Join Date: Sep 2009
Location: Seattle, Washington
Nothing I said disagreed with anything you just said. I'm not trying to be antagonistic. I agree totally that quarantining longer after a known sickness is a good idea.
What didn't make sense was you said that most of these sicknesses have a 21 day life cycle, in which case symptoms would appear within those 21 days, so a 45 day period to see if symptoms develop seems excessive (2.5x the life cycle; symptoms would surely have appeared). I assume you were talking about one of the more rare pathogens that has a longer than 21 day cycle, so symptoms possibly would not have appeared within 4 weeks.
I see that there are diseases that take longer than 2-4 weeks for symptoms to appear, so to be on the safe side you recommend the 45 days.
But most common illness will be detected within 2-4 weeks. It is a pretty safe bet, although one is still taking a gamble. You mentioned one disease that didn't develop until several months after you had your fish. No one quarantines their fish for several months, so one can never be 100% sure that the fish are healthy. 2-4 weeks makes the odds higher in one's favor; 45 days would make them higher still.
This is going to be my last post on this, unless the thread takes a different turn.