Neon / Tetra disease

Definition and symptoms

Neonsalmler / Roter Neon
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The neon disease is a parasitic infectious disease that mainly affects characins and barbels. It is particularly common in neon tetras, which is how it got its name. The pathogen, Pleistophora hyphessobryconis, belongs to the microspora and is a unicellular parasite that reproduces in the body cells of fish. The disease is contagious; other fish in the stock can become infected. The disease can be fatal. Treatment is only possible to a limited extent.

Infected fish lose their colour; milky white spots form on the body of the fish and the back can bend. Due to the loss of balance in the water, they show conspicuous swimming behaviour. The fish lose a lot of weight and detach themselves from the rest of the shoal. At night the fish are restless. Due to the weakening of the fish, secondary infections can be added. In the following you will find a list of all

Symptoms of neon disease

  • Colour fading
  • milky white spots on the body of the fish (back and torso)
  • Scoliosis
  • Loss of balance and noticeable swimming behaviour
  • Lack of appetite and emaciation
  • nocturnal unrest
  • Secretion
  • Secondary infections (e.g. fin rot)
]Do not confuse the neon disease with thewrong neon disease or white mouth disease. Here too, white spots can appear on the body of the fish. But the white mouth disease can affect many species and the pathogen is the bacterium Nocardia asteroides.

Causes of the neon disease

The unicellular parasite can infest the fish and rest in them for a long time until the disease appears. Therefore, a fish that is a carrier but does not show any symptoms externally can be a source of infection for other fish. When buying new fish from an aquarium, you should always pay attention to whether other fish from that tank show abnormalities. If in doubt, the purchase should be omitted. The parasite multiplies in the body cells of the fish. The spores are released into the aquarium water and attach themselves to food components that are taken up by the fish. The fish can also become infected by nibbling on sick or dead fish that have been left in the aquarium.

Course of the disease

After a fish has absorbed the parasite spores, they migrate into the intestine. Here they bore into the intestinal wall and enter the fish’s blood or lymphatic system. There they circulate until they meet a muscle cell. The reproduction takes place in the muscle cell. The parasite divides several times; a pansporoblast with thousands of spores is formed. The muscle fibers of the cell are destroyed and turn white. Once the cysts have matured, they break open and the spores are released into the water where they can infect new fish.

If an infected fish is removed from the tank in the early stages of the disease and kept under good care and optimal hygienic conditions, the fish’s immune system may be able to keep the parasite in check for a long time. Infected fish die more often from secondary infections caused by weakening and unhygienic farming conditions than from the parasitic disease itself.

In the advanced stage of the disease, when the body is already covered with white spots, it is often no longer possible to save the fish and the infestation ends fatally.

Treatment of the neon disease

An infected fish must be separated from the other fish as soon as possible and placed in a Quarantine tank be implemented. Also a cleaning of the entire aquarium should be considered. The water should be changed, plants should be replaced, furniture and substrate should be disinfected. Since it is not known how long the spores of the parasite can survive without a host in the environment, it is best to avoid reoccupying this tank for some time. A good filter system for the replacement pool is mandatory, as well as regular partial water changes. In addition, a reduction of the water temperature has proven to be effective, since the parasite cannot develop optimally below 30 degrees Celsius.

There are noeffective cures for the neon disease. A therapy can therefore only be supportive, with the aim of avoiding secondary infections. Optimal husbandry conditions are essential here.

The treatment measures at a glance:

  • Transfer fish to a quarantine tank
  • Partial water change at short intervals
  • Keep water temperature below 30 °C
  • install a good filter system
  • Support of the fish's immune system with species-appropriate and vitamin-rich nutrition
  • Disinfection and quarantine of the old basin


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