well I did a no go a few days ago and put in five baby neon tetras in a tank, one of them did not want to school and shortly later died......the following few days three of my fish died that were in that tank and after elimianting the possibility of amonia/nitrites/and nitrates and a few other things I decided it was the neons which i was so in a hurry to get them in the tank I didnt put them in the QT first. and now my gourami Aisu has scales flaking of in the rear and it looks like a sore so him along with the rest of the sickly looking fish will be spending some time in the QT to heal and rid them selves of any sickness so my advice to all is use the QT with new fish no exceptions