Neon Tetra Disease

Paracheirodon innesi - Neon Tetra
Kai Schreiber

Neon Tetra disease is more common than many aquarium enthusiasts realize, and affects species beyond neon tetras. Named after the fish that it was first identified in, the disease strikes members of the tetra family most often. Other popular families of aquarium fish are not immune.

Cichlids such as Angelfish and Cyprinids such as Rasboras and Barbs also fall victim to the disease. Even the common Goldfish can become infected. Interestingly enough, Cardinal tetras are resistant to the ravages of Neon Tetra disease. Caused by the sporozoan, Pleistophora hyphessobryconis is known for its rapid and high mortality rate among neons. To date, there is no known cure, the only 'treatment' being the immediate removal of diseased fish to preserve the remaining fish.

The disease cycle begins when parasitic spores enter the fish after it consumes infected material, such as the bodies of dead fish, or live food such as tubifex, which may serve as intermediate hosts.

Once in the intestinal tract, the newly hatched embryos burrow through the intestinal wall and produce cysts within the muscle tissue. Muscles bearing the cysts begin to die, and the necrotic tissue becomes pale, eventually turning white in color.


  • Restlessness
  • Fish begins to lose coloration
  • As cysts develop, body may become lumpy
  • Fish has difficulty swimming
  • In advanced cases, spine may become curved
  • Secondary infections such as fin rot and bloating

During the initial stages, the only symptom may be restlessness, particularly at night. Often the first thing an owner will notice is that the affected fish no longer school with the others. Eventually, swimming becomes more erratic, and it becomes quite obvious that the fish is not well.

As the disease progresses, affected muscle tissue begins to turn white, generally starting within the color band and areas along the spine. As additional muscle tissue is affected, the pale coloration expands. Damage to the muscles can cause curvature or deformation of the spine, which may cause the fish to have difficulty in swimming. It is not unusual for the body of the fish to have a lumpy appearance as the cysts deform the muscles.

Rotting of the fins, especially the caudal fin, is not uncommon. However, this is due to secondary infection rather than a direct result of the disease itself. Bloating is another secondary infection.


  • None, separate or euthanize diseased fish

There is no known cure. To ensure all fish are not lost, remove diseased fish from the tank. Some species, such as Angelfish, may live for quite some time. They should be separated from uninfected fish to avoid spreading the disease.


  • Quarantine new fish for two weeks
  • Maintain high water quality
  • Do not purchase from a tank with ill fish

The best prevention is to avoid purchasing sick fish and to maintain high water. Carefully observe the suppliers fish. Do not purchase any fish from tanks where there are sick, dying, or dead fish present. Fish that do not school, or hang apart from the others, should be suspect.