Neons are imported and from totally different water. Your other fish are used to your water and the neons are not. Could be after they died, the others were nipping at them. That would also be normal for fish.

I suppose this will sound strange to some but I no longer lose neons now that I stopped acclimating them. I simply net them out of the bag and drop them in a quarantine tank with light out for a couple days. I used to lose 2-3 out of every new batch when I acclimated. When I stopped messing around with them, I stopped losing them. Go figure.

Those wee fish go through a lot. Dragged out of the wild, tossed into bags, flown to the US to a distributor and dropped in totally different water. Then taken to the fish store and into different water again with a net chasing them around all day. Then here they are at our homes again in different water. No wonder they have a tough road to ho'.