First, I think it's fantastic that you're getting fecal tests done for your new leos. This is something not enough reptile owners do, not even the majority of breeders.
To answer your question, yes, continue with the quarantine period even if they test clear. Oftentimes, a single fecal test isn't enough to determine an animal is parasite-free. It really depends on the parasites' life cycle and if they happened to lay any eggs at the time your leos pooped. (That's why it's recommended to perform at least 2-3 follow-up fecals if you have to treat for hookworms or coccidia.) It also depends on what type of parasites we're talking about because some parasites require more than just a normal flotation.
So keep quarantining your leos and watch out for any unusual stools or behavior. Do this for AT LEAST 90 days. I don't know where the idea that 30-60 days is enough. No one I know who has ever dealt with parasites quarantines for less than 90 days. I even know of several people who quarantine for one full year before they're comfortable introducing new animals to their colony.
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chickabowwow
