Fish infected with Neon Tetra Disease will show signs of becoming pale in color (white patches beneath their skin). The fish will not school with the others and become listless. Through the latter stages of the disease the fish´s body will begin to degenerate. Usually the tail end of the body will seem dwarfed and becomes useless, this will cause the fish to have trouble swimming. Upon witnessing these symptoms, death is imminent, consider euthanasia. To my knowledge their is no cure for the disease. I have seen the disease many times and have yet to see it become an epidemic. The disease will however continue to infect your fish until the cause has been remedied. Neon Tetra Disease is usually caused by stress due to poor water conditions, shock (dramatic change of environment), or being harassed by other fish. The disease is fatal but it will not kill them that quickly. It is a degenerative disease that goes through many phases and may take weeks before they will die, the actual amount of time depends on the general health of the fish. The disease is borne of a cyst and it will migrate to the digestive system and eventually the muscles of the infected fish.