I also highly recommend a QT tank for any new arrivals. I had a similar experience to yours where a particularily virulent strain of bactera hit my mbuna tank, I lost 13 fish in less than 24hrs. While I'm not sure if the catfish I introduced a couple weeks prior introduced the bacteria, I've be using a QT tank ever since, and haven't lost anymore fish.
I'm sorry for your loss, and wish you luck on the new stocking.
I'm sorry for your loss, and wish you luck on the new stocking.
