I would tend to believe a bacterial infection or parasite.. tetras are prone to disease.. trust me.. I know first hand. I have lost so many fish like this. I would say that you should always quarantine fish when you buy them to make sure they are healthy prior to you adding them into your main tank. I would remove the other neons that are still alive and quarantine them if possible.. if not I would start to dose your tank with meds. quick cure, melafix or pimafix. good luck and keep us posted
|