1077: If you read all of the details I provide, you'll find your answers as to the water conditions, and yes, it's very heavily planted. The entire floor is carpeted in microswords and stem-plants.
Spook: I was under the impression that the disease came out later on through the fish's life? It's completely possible, I never considered it and I never knew it could affect Danios as well. But that makes total sense since Danios are largely inbred and are at high risks of genetic diseases and mutations.
Twocents: I had been dosing them with Oil of Cloves, then my husband made sure that they were out with a 'thump' from his forefinger and thumb. It sounds awful, I know, but we don't want them waking up later in the sewer wondering how much they had to drink. X3
We removed the Danios into a medic tank of 87-degrees (to match the 55g) and slowly decreased the temperature over the course of a day. However, even with the change of temperature and putting them in their ideal conditions, the Danios kept dying of the same symptoms. We gave it three days in hopes that it was the 55g's temperature that was affecting them in that manner, but it wasn't. It was simply Danio-on-Danio war; it sort of reminded me of Bloods and Crips.
We talked with various hobbyists, and every one of them had the same response: it's rare for Danios to get aggressive towards each other, but it does happen, so the only thing that can be done is to return the offending fish or isolate them (or the bullied fish) from the rest of the tank by giving them their own tank.
We've since then removed the zebras and have taken them back to the store that we bought them from, and unfortunately only three of the other Danios have survived. We also removed them and took them to the same store that we bought the zebras from, and saw that they got into a tank with the same breed. So the zebras are with other zebras, and the leopards are with other leopards.
Unfortunately no pearls survived.
We've done more research on more dithers, and we've decided on coral red pencil fish. We'll set the tank at 83-degrees and call it a day, but we're going to give our tank another month before we introduce more fish to it. One, we want to make sure that all of the ich is gone, and two, we want to see some of our newly-added plants fill out first.
Thanks for the help and advice guys. :)