I sometimes have this issue with neons dying like this unless I didn't add some kind of stress coat in the tank, and float the bags in the water for an hour or so... Then I leave the light on overnight... I found with neons if you put them in a new tank and don't leave the light on overnight they will die..
Stress Coat is mostly a gimmick IMO... other than the fact that it does act as a dechlorinator. For that, it is useful, although Prime is more concentrated and thus, cheaper to use in the long term.
Fish are weaker when they are sleeping. You know when you have a cold like a sore throat and you go to sleep and wake up and the throat is way worse then it was when you were awake ? Its the same thing with fish... granted rest cures colds.. but still..
This reads as though you're proclaiming it as fact, yet there is nothing to back it up. Care to elaborate?
That's what I learned so try again and this time leave your lights on.
Most people will turn their lights OFF to acclimate new fish. Lower lighting often equals lower stress, as fish are demonstrably less active during lights-off periods.
Also did you float the bags in the water before putting them in ?? Sometimes like people said a few neons will die.. That's why I get like 10 of them when they are on sale for $1 at petsmart.. I usually will have 4 die, and then I return them and get more... Once you get neons that don't die in your tank its easy to keep them alive... As long as you don't let your nitrates get high. I have had 7 in my 27g and 30g for a long time now. I originally started with 10, then like 5 died and I got 5 more and 3 died and now I have had 7 for like 4 months
Sounds like the fish aren't too healthy when they get to the store. The survival rate listed above isn't great. Maybe try buying from another source.