Neon tetra, Paracheirodon innesi
Neon tetra disease, Plistophora hyphessobryconis belongs to a group of organisms called sporozoan parasites. Little is known about this group of parasites. The disease doesn't just infect neon tetras, other similar fish can also become infected.
The first sign is localised loss of colour, small fish like neon tetras often fade their colour at night and this is normal but with this disease the loss of colour is usually located in one small patch when the rest of the fish is displaying normal colours.
Initially the fish will continue to live as normal but soon after the first symptom appears the affected area will start to waste away, this wasting will ultimately lead to the spine becoming kinked and the fish will no longer be able to swim normally.
Once symptoms have shown the fish is doomed, fish showing signs of this disease never recover and so to prevent further suffering, once a fish has been positively identified with this disease euthanasia is the kindest option.
Unfortunately there is no treatment for this condition. The best way to prevent it's spread is to remove any fish showing these symptoms before the disease can be passed on to other fish. Try an anti bacterial treatment because there are a few bacterial diseases which give rise to similar symptoms. If this doesn't help then it is neon tetra disease. If the fish recover with this treatment then it wasn't caused by neon tetra disease but was a bacterial infection. It is this which has probably led to rumours of certain products being able to cure this disease. Euthanasia is the best option as soon as a fish is seen with symptoms this will help stop the spread and prevent unnecessary suffering.
When selecting fish to buy, especially small tetras always carefully check the tanks occupants if any look unhealthy then reject all the fish in that tank. It only takes one fish with this condition to infect an entire aquarium.
The infectious agent causing neon tetra disease can remain active in an aquarium for several months with out a host. This means that any fish which can be infected by this disease should not be returned to an aquarium where this disease has been present for at least six months.
There is a rumour that cardinal tetras are immune to this disease, they aren't. Cardinal tetras can become infected as can many other small tetras, rasboras and even some cichlids. Although in the case of cichlids they often survive the infection but the wasting and deformities will always remain.
Even if you follow these guidelines you should expect to see some losses, this is a very difficult disease to control.
Neon tetra disease IS incurable regardless of any other claims. Early action of removing infected fish can stop the spread of the disease.
There is a bacterial disease with almost identical symptoms, once the infected fish has been moved to its own tank there is nothing to lose by treating with an antibacterial remedy. If it is neon tetra disease the fish will still die, if it is the look a like bacterial disease the fish may be saved.
Do not wait before removing infected fish or you will lose many more as a result.