1 week, this proves to be the best method i have found, generally speaking in the first few days you will see any signs of disease or abnormalities, however it can take up to a week for some signs to show, if after this first week they show no signs of stress and are eating healthy and show no signs of disease, i put them into the tank they are going to live out their lives in.
Brandon
oh btw the quarantine tank has no substrate, just a few pvc chunks for caves and a few taller fake plants. this makes it easy to view the fish also makes cleaning the q-tank a breeze.
I remember being told that in the case of an ich outbreak the little white thingies will detach themselves from the fish at one point and fall into the gravel where they would multiply (or whatever thedy do at that stage) then find their way back onto the fishies...so if you dont have gravel in the quarinteen tank it makes it easier to just clean up the bottom during that stage and you'll be sure that there are no bad critters left hiding in rocks at the bottom....i guess...maybe? Just a theory...