As for your "mini-epidemic", I had recently lost fish in an established aquarium, 74 to be exact, in 6-10 hours. I rescued only 3 fish. 1 Danio Zebra, 1 Dwarf Blue Gourami, & 1 Rainbow Shark. They seem to have come down with a serious case of gill flukes. They were treated in a separate tank with Furan-2, Ick Cure & medicated food pellets crushed. Ever since that, my new setup uses a canister filter with a UV sterilizer on the output side. The UV sterilizer was added due to an Ick outbreak 1 month after setting up new tank. Plus, I found new born hatched zebras free swimming on the surface. Haven't had anything happen since. I also keep an eye on the temperature of the tank. Make sure it doesn't fluctuate. I keep mine at the highest temperature range my fish usually live in. This keeps there appetite & there metabolism up . But it does speed up there life cycle, so they don't live as long either if keep up for too long. If your worried about the whole community tank, you can add Coppersafe from Mardel Labs to the whole tank just to be safe. I've also used it before, its not as potent at killing diseases quickly, but to me it doesn't shock your tank either. Some plants will be affected by it though. Remember to remove the carbon from your filter, so you don't remove the medicine from the water. *crazysmiley*