I'll share a couple stories of QT woes since I've had the tank setup.
Back in September I had 3 fish in QT; I had mentioned as much somewhere along the line. They were a rhomboidalis, rubricaudalis, and a carmabi. All were doing great and I was on to week 3 of QT, when suddenly they all went from alive and fine one morning to all dead within 8 hours, with weird red streaks. Some sort of gram negative infection.

I loose very few fish in QT, so this was a bit depressing.
My next endeavor was trying a group of 6 Clepticus parrae. They came in just fine, but were
tiny; all 1.5" or so. I found right away that they needed a lot of flow, otherwise they stayed pretty spooked and would not eat. Being so small, they were difficult to offer food to, as fish eggs and ova were about the only thing I had that was small enough for them. Ultimately, I simply couldn't feed them enough, often enough. Slowly I lost them one by one on weeks 4-6 of QT. I managed to get two to the DT, but one died in the acclimation box (was already weak) and the sole survivor was released - to never be seen again. If I were to try again with them, I would definitely start with larger specimens, as I feel I would have had a fair shot had they been large enough to offer more foods to.