I'm not sure what this specific member means when saying observational QT but i do observational QTs and from my understanding, a typical observational QT usually is not carried out for longer, or even the same amount of time as a medicated QT. The purpose i do observational QTs is to get the fish eating well and make sure he's not displaying any obvious signs of disease which a healthy appetite and normal behavior are usually pretty good sign of...imo, a medicated QT is likely much more stressful for a healthy or sick fish and although it may cure a sick fish if you happen to get one, I'd expect the fish to be very stressed and likely have a long way to go before actually returning to a healthy fish at baseline...reason i do a brief observational QTYes from my research online, that was only one of the few bio media that did not absorb copper. I think the only disadvantage to observational QT is the wait time. Adding copper and prazipro would cut that in half. But if I go with inverts in display tank first, I might just do observational QT instead of treating with copper as I have to wait 72 days anyway.