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Neon Tetra & FNT Disease; Sporozoan Fish Infection


NEON TETRA DISEASE (Identification, prevention and possible treatment of):
Also the similar infection; FNT Disease (False Neon Tetra Disease)

(Scroll further into the article for FNT)

By Carl Strohmeyer-PAMR 35+ years experience
Updated 10/25/14

Neon Tetra Disease
This term is often a catch all name for diseases of Neon Tetras specifically and many other fish as well, especially other Tetras.
The usual cause is by a Sporozoan (parasitic spore-forming protozoan which reproduce sexually and asexually in alternate generations by means of spores); Pleistophora hyphessobryconis, although there are other causes including many fungi that will imitate this Sporozoan infection.

The true Pleistophora hyphessobryconis infestation is very difficult to treat, and basically impossible to treat in the later stages of this infestation, which is when most aquarists first notice this disease.
However, contrary to popular opinion on the web and elsewhere where many are just repeating what they hear elsewhere it is somewhat treatable in the early stages and VERY preventable from spreading.

Occasionally rare gram positive bacteria will also cause these symptoms (fading, loss of color, etc.) which require a different course of action.


The disease cycle begins when parasitic spores enter the fish after the fish ingests infected food or organic debris, such as the bodies of dead fish, or live food (often Tubiflex Worms).
After the spores enter the intestinal tract, the newly hatched embryos burrow through the intestinal wall and produce cysts within the muscle tissue. These muscles containing the cysts begin to die, resulting in a pale whitish tissue.

Initially the only symptom may be restlessness especially when lights are turned on and off.
The infected fish often will stop schooling with others of their species. Soon the swimming becomes more erratic and the tell tale symptom of the white muscle tissue becomes apparent.

Other fish are susceptible to this infestation as well, this includes and is not limited too:
*Most Tetras
*Many Danios (including White Clouds)

Symptoms in order of progression:

TREATMENT (and more importantly; stopping the spread of this disease):

A with Methylene Blue is the first step.
To prepare this bath I use 1-2 teaspoon 2.303% solution per 5 gallons in a bath of aquarium water from the tank the fish you wish to treat came from, I usually use about a ½ gallon of water, however you may use less. With Kordon's Methylene Blue, 10-20 drops per gallon will work

Measurement of the Methylene Blue does not need to be too precise as this bath should only be used for about 30 minutes and Methylene Blue is safely overdosed for fish in baths, dips, or bare hospital tank. However overdosing in established aquariums can kill beneficial nitrifying bacteria.

This bath’s effectiveness is improved further by the addition of salt (at 1 teaspoon per gallon) AND Metronidazole at double the normal "in-tank" dose recommended by the manufacturer.

A Medicated Bath Resource:
How to Perform a Medicated Bath
Recommended Product Resources:
*Kordon Methylene Blue Remedies
*SeaChem Metronidazole

Make sure you keep the water in a warm area, as in a cold room the water temperature can drop rapidly which would stress the fish.
Do NOT pour this water back into your display aquarium when finished.
This bath can be performed twice per day.

Adding Nitrofurazone to this bath at double recommended tank dose can improve results.
Erythromycin can be substituted for Erythromycin, especially for FNT Disease.
This bath is helpful for the both “True Neon Tetra Disease” and false neon tetra disease (FNT Disease).

In the tank you need to treat with Quick Cure, or ParaGuard-Parasite Treatment combined with either Furan 2 or Metronidizole.
Medicated Wonder Shells are excellent as a follow up treatment or for mild infections.
Continue this treatment for 7-10 days.

Recommended Product References:
*API Erythromycin
*SeaChem ParaGuard-Parasite Treatment
*Quick Cure
*Furan 2
* For a good follow up treatment either after fish have mostly recovered or as a preventative:
Medicated Wonder Shells

For very mild cases, an alternative to a bath would be the external application of Hikari Bio Bandage to the tetra (make sure both sides of the fish are applied to).
Product Resource: Hikari Bio Bandage from AAP

If at all possible I strongly recommend attaching a UV Sterilizer after treatment or removal of sick (or dead) fish.
This device will help in the spread of disease and improve Aquarium Redox (which improves immunity).

For more information about UV Sterilization. Please read this VERY IN DEPTH & RESEARCHED article:
Neon Tetra and FNT Disease Prevention using UV Sterilization
This article explains the benefits and myths about TRUE aquarium and pond UV sterilization as opposed to the many UV Clarifiers sold via Amazon & eBay masquerading as true UV Sterilizers.
It is also essential for UV Sterilizer to remain effective for prevention and Redox aid, that you change your UV Bulb every six months (regardless of some claims by less than honest long life, yet low output UV Bulb sellers)

Redox Reference: Aquarium Redox

Recommended Product References:
*High Output Hot Cathode UV Bulbs
*UV Sterilizer

A medication containing Metronidazole or an additional treatment of Metronidazole in tank can be very helpful as well.
Note: this is infestation is difficult to treat and takes a "medication cocktail" approach to defeat.

In the even more rare cases of FNT disease Erythromycin may be effective (I still recommend the medicated Methylene Blue bath). See False Neon Tetra Disease (FNT) section of this article below.

Medication Information Resources:
Aquarium Medications; How Metronidazole Works
Aquarium Medications; How Erythromycin Works


It is noteworthy, based on my “house calls”, emails, customers, etc, in my years of Aquarium Maintenance & answering questions online, that the majority of Tetra Disease diagnosis are incorrect. Sadly this disease is often misdiagnosed.

Here are (in order of most common) misdiagnosis causes of Neon Tetra Disease:

Basically locating a good source (& sticking with it) for your Tetras and other fish that are easily infected by Neon Tetra Disease (& FNT disease) and following all or at least most of the procedures outlined in the article; “Aquarium Disease Prevention”, this disease should actually quite rare.

In fact I have not nor have our sister Aquarium Maintenance company’s regular full service clients had a case of this disease in quite some time (years as of this update).
Most cases were diagnosed with “occasional” service customers or online/forum questions.

Recommended Aquarium Maintenance Companies


Medicated Wonder Shell fungus treatment
I will note it is common to confuse true Neon Tetra Disease caused by the Sporozoan; Pleistophora hyphessobryconis with other diseases such as many fungi infections and often gram positive bacterium, this is called False Neon Tetra Disease or FNT Disease and is generally caused by less common gram positive pathogens.

These false infections often do not have the symptoms leading up to the white/ pale tissue and the discoloration is more faint and much less white and defined than True Neon Tetra Disease.

As with True Neon Tetra Disease caused by Sporozoans, a medicated bath is an important first step.
However in tank (or better hospital tank) treatment should consist of a primarily gram positive “cocktail” such as Erythromycin, possibly adding either Medicated Wonder Shells, API Fungus cure, or even Kanamycin.

Please note that these combinations (that all start with Erythromycin) are EXTREMELY hard on bio filter bacteria, so use in a quarantine/hospital tank is strongly recommended.
As lesser strength "in-tank" treatment, but less harmful to bio filtration would be Kordon Herbal Ich (& Fungus) Attack

As a side note, I have observed FNT disease (not True Neon Tetra Disease) when many cycling aid products have been used, and since many use aerobic/gram positive Heterotrophic bacteria (possibly Actinomycetes), there may be a relation.
This is only an observation, but I have noted this on several occasions with many Tetras (as well as few Danios/Rasboras), so I would cease the use of these products if FNT Disease is suspected. I should note that I have not observed this with the better Cycling aids such as Fritz or the newer SeaChem Stability.

Further Product References:
*Kordon Herbal Ich (& Fungus) Attack
*API Fungus Cure
*SeaChem Kanamycin
*To aid in nitrifying bacterial replenishment after treatment: Effective Stabilized Natural Bacteria; Stability


If all these steps are followed my success rate in stopping the spread of this disease is nearly 100% and treating early stages at around 20% to 50%.
If you cannot add the UV Sterilizer, the other steps will still help a lot, especially in stopping the spread. But if you can afford a UV Sterilizer, purchase one, and not a UV Clarifer sold at Amazon, PetCo and others such as the Submariner or Green Killing Machine, rather a TRUE LEVEL ONE Sterilizer such as the TMC Vecton, SunSun Terminator or CUP series (with prefilter)!

However, it is important to follow as many as possible of these steps as Neon Tetra Disease does not spread in the same manner as other protozoan infections such as Ich or velvet, making it difficult to treat. This is why this “treatment cocktail” is often required.

Other Recommended Reference & Product Sites

*UV Sterilizer Reviews: Equipment to AVOID

*TMC Vecton and Advantage Premium High Dwell Time UV Sterilizers

*SunSun CUP Series Submersible True UV Sterilizers

Aquarium Lighting

The most in depth aquarium lighting article, an important read even for basic fish keepers!

*Fish Nutrition

*Aquarium Ich

*Pond Care Information

TMC Premium Fluidized Sand Bed Filters

Premium, second to NONE Aquarium Bio Filters, that with optional Oolitic Sand also maintain essential marine aquarium calcium levels, alkalinity, & electrolytes that are important to ALL Marine life, Goldfish, African Cichlids, Livebearers & more

Spirulina Fish food for neon tetra health and disease prevention
Spirulina 20 Fish Food Flake

The best balanced fish flake food diet for Tetras and other fish for disease prevention

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  8. Activated Carbon
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  23. Octopus as Aquarium Pets
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