external symptoms
- Fish lose their color.
- Milky white patches in the back fabric or on the body, often in the red band of neons
- The spine bends.
- Fish lose weight.
- Fin rot occurs.
Behave
- Fish show unusual swimming behavior.
- Fish swim restlessly back and forth at night.
- Fish separate from the school.
internal symptoms
- Cysts containing the spores can be seen under the microscope.
Photos of neon disease
Clicking on a photo shows the whole picture, if available.
Photos: Gerhard Fischer
Neon tetra with neon disease.
Photo: Felix Wüst
Neon tetra with neon disease.
Photos: Manadis (Forum)
Red Neons with False Neon Disease.
At the same time, bacterial infections appeared in another aquarium, other fish species were not affected.
The trigger was probably an increased susceptibility of the tetras due to hard aquarium water with 13°gH and 8°kH after a move.
Photos: Babo
Neon tetra presumably with neon disease. The fish turned pale and very thin within a few days. After being separated from the other fish, it regained some color at first, but died after another four days.
Causes of neon disease
The neon disease is caused by sporozoa of the species Pleistophora hyphessobryconis. This pathogen belongs to the microsporidia. These are unicellular parasites that can be found in the cells of almost all animal species. Fish are particularly affected. The disease got its name because it particularly often affects neon tetras. In addition to neon tetras, other tetra species (e.g. red-headed tetra, glow-light tetra) and barbs (e.g. zebrafish) can also contract Pleistophora. The red neon is not affected by the disease. Red neon with similar symptoms is very likely to have the so-called Fake neon disease.
Infected fish can often carry neon disease undetected for a long time before external symptoms become visible.
The pathogens spread without an intermediate host. By eating dead, diseased fish or food infested with spores, the fish ingest the spores (microsporidia) of the pathogen. Once the spores reach the fish’s intestines, the protective coating dissolves and they form amoeba-like cells. These migrate through the intestinal wall and finally reach suitable muscle cells with the blood and lymphatic fluid. Once inside the muscle cells, the cells divide several times, protected by the fish’s immune system. They form spherical cysts (pansporoblasts) in which thousands of new spores grow. The spores are each 2 to 20 microns in diameter. They consist of a nucleus and amoeba-like protoplasm.
The muscle fibers are destroyed by the cysts and spurs. The dead muscle strands turn white. The cysts rupture and the adult spores are released into the water as the fish dies and the muscle tissue breaks down. The new generation of spores are again ingested by other fish by eating the dead fish or after attaching to food.
Cysts may form in the kidneys, causing spores to be excreted in the urine of live fish.
As a rule, however, the transmission path can be interrupted if diseased and dying fish are removed from the aquarium.
Since apparently healthy fish can also carry the pathogen, an outbreak of the disease must be prevented by the best keeping conditions. The pathogen can even attack the eggs. Fully developed panspuroblasts were found in neons that were only a week old. How long the spores can survive without a new host is unclear. After an infection, however, a long quarantine must be maintained for the infected aquarium. Some aquarists destroy the plants from an infested aquarium, boil the substrate and disinfect all furnishings.
Neon disease is often confused with white mouth disease (columnaris) because white patches form in both diseases. One therefore also speaks of the real neon disease (neon disease) and the false neon disease (white mouth disease).
Also referred to as false neon disease is a bacterial infection with the bacterium Nocardia asteroides. These bacteria infect different species of fish. The symptoms correspond to those of other bacterial infections, e.g. B. flat skin turbidity, pop eyes, bloated abdomen and emaciation.
Red tetras with the false neon disease show very similar symptoms to neon tetras with the true neon disease. The musculature turns white and the colors disappear.
treatment suggestions
There is currently no safe treatment option for neon disease. Toltrazuril, which is used against sporozoa in chickens, may help. There are still no effective remedies for neon disease in ornamental fish, even if this is repeatedly claimed.
Infected fish must be isolated immediately. Infested fish can live for a long time with mild infections. In some cases, the infection even gets better. However, the affected animals can continue to harbor the parasites. Infected fish often contract bacterial secondary infections, from which they eventually die. Maintaining optimal conditions improves the life expectancy of infected fish.
Fish with severe infestations should be killed. In any case, it must be prevented that other fish eat dead animals or eat animals that are about to die.
Aquariums in which a heavy infestation of neon disease has occurred should be carefully disinfected.
False neon disease can be cured in its early stages with antibiotics. If there is already clearly visible damage, successful treatment is not possible. Even with bottle neon disease, sick animals must be removed from the aquarium immediately.