Sounds like your neons do have it. It shows itself in white edged, "rotting" fins, usually fraying fins too.
You can cure it with any antibacterial fish medication. I use Melafix, but only because I can't find Maracyn I and II, which everyone else on here suggests.
I have had my tank up and running for about 3 months now. I lost most of the first fish I had with Ick. It has noon been about 5 weeks since I did that treatment and got rid of the Ick.
I purchased 5 new glowlights (I keep wanting to call them neons...) last saturday and these seem to be the only fish that have the fin rot. They seemed fine when I brought them home from the store, at least I did not notice it then.....
Did you acclimatize the glowlights first? Floating the bag, then over an hour or so (more if the store's pH is dramatically different from yours) drain a little of the store water and add a bit of yours until the water in the bag is all your tanks. Then drain most of the water in the bag and put the fish in the tank.
You can know that the tank is or isn't cycled by testing the water for ammonia, nitrites and nitrates. If you don't have a test kit, get the Aquarium Pharmaceuticals Freshwater Master Test Kit (whew!). Don't get a strip test, as these are notorious for being inaccurate. They might be a bit cheaper but they don't last as long. The test kit I mentioned has more than 700 tests.. Most strip tests usually only have about 25, but the more expensive ones have 100.
The only medication I could find in town today was Fungus Cure. It said to add 1 capsule to every 5 gallons of water, so I added 4 as my tank is a 20 gal tank.
The directions said it would turn the water green! Boy did it ever!! Like Neon Green Water!!!
It said to leave this for 48 hours and then add 4 more for another 48 hours and then do a 25% water change. Will this cure the fin rot this quick?
There is no pet store in our small town the closest one is about 40 minutes away. I have to get the few things that I need at the local feed store. Is there a list of stuff that I should alway have on hand incase this happens again??
What company was the Fungus Cure made by? Just wondering.
Remember to keep your water super clean. Bacterial diseased, including finrot, often result from poor water conditions. Also, try raising your temp to 82 degrees. This is supposed to help kill those nasty little germs.