They swim with no direction and sometimes in a corkscrew type pattern. After, they look exhausted and settle on the bottom of the tank not moving I would suspect Neon Tetra Disease. Here is a link to an article on it (offsite) - http://www.aquarium-pond-answers.com/2007/02/neon-tetra-disease.html
This is a difficult disease to cure, and is somewhat common. Sometimes the best course of action is to destroy the infected fish.
This is a difficult disease to cure, and is somewhat common. Sometimes the best course of action is to destroy the infected fish.
