You might want to quarantine the rest of your neon tetras just in case they have caught the disease. Were you able to get the dead neon tetra out of the tank immediately? The other neon tetras may have nipped at the dead one which would get them sick too.
A forum community dedicated to Aquarium owners and enthusiasts. Come join the discussion about collections, displays, product reviews, accessories, classifieds, breeding, health, behavior, housing, care, and more!