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Neon Tetra Disease: Causes, Symptoms, Treatment & Prevention

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Neon tetras are resilient fish capable of adapting to various water conditions. These beautiful creatures are popular among both aquarium novices and enthusiasts.

However, they are susceptible to neon tetra disease, a condition that poses a significant threat to my aquarium’s entire population.

So, what exactly triggers neon tetra disease? What are the signs of neon tetra disease, and how can I prevent or treat it? This article will provide answers to these questions.

What Is Neon Tetra Disease?

Neon tetra disease is a condition that not only affects neon tetras but also other species of fish.

Although it was initially identified in neon tetras, it can infect discus, mollies, angelfish, zebrafish, guppies, betta fish, and other tetras.

However, cardinal tetras are more resilient against this disease.

The main culprit behind this ailment is Pleistophora hyphessobryconis, a parasite that undermines the overall health of the fish.

This parasite belongs to a group of spore-forming parasitic fungi that generate infectious and resistant spores.

These spores enter the fish’s body when they consume infected fish carcasses or contaminated live food like tubifex.

Once inside, the spores affect the fish’s tissues and organs, including the stomach, digestive tract, intestines, and skeletal muscles.

As the disease progresses, it gradually causes muscle and organ degeneration, ultimately leading to the fish’s demise.

Is neon tetra disease contagious? Yes, healthy fish can become infected by consuming the remains of deceased fish.

What Causes Neon Tetra Disease?

The primary cause of neon tetra disease is Pleistophora hyphessobryconis. This parasite consumes my fish from the inside out.

The parasite enters the host fish’s body when:

  • The fish consume deceased, infected fish.
  • The fish consume contaminated live food.
  • When the fish’s immunity has been compromised, enabling the parasite to thrive in the tank.
  • When introducing infected fish into the aquarium.

Once inside, the parasite spreads from the digestive tract to the tissues, muscles, organs, and skeleton.

Pleistophora hyphessobryconis thrives in fish tanks with warm water, low pH levels, reduced oxygen levels, and organic-rich conditions.

These conditions often cause stress in fish, making them more susceptible to infections and neon tetra disease.

If you suspect that your fish have neon tetra disease, watch out for the following signs:

Symptoms Of Neon Tetra Disease

Diagnosing neon tetra disease can be challenging since it exhibits similar symptoms to other bacterial and parasitic infections.

Nevertheless, fish with this condition display the following signs:

1. Restlessness

Infected fish become restless and alter their swimming patterns, particularly during the initial stages.

This is more noticeable among schooling or active fish. Additionally, my fish may swim in irregular patterns.

2. Hiding

Sick fish tend to retreat and hide in live plants or caves, limiting their interaction with other fish as they try to recover from the energy drained by the disease.

Moreover, they may have difficulty swimming around the fish tank.

3. Dull Colors

Sick neon tetras gradually lose their vibrant colors and appear pale, indicating that the neon disease has attacked the muscle tissue.

However, it’s important to note that losing coloration doesn’t necessarily mean my fish have neon tetra disease, as fish often turn pale when under stress.

3. White Cysts

Sick neon tetras develop white cysts and bumps as the disease progresses.

Once the parasite attacks the intestinal wall, it spreads to the muscle tissues, resulting in cyst formation. These cysts may also become lumpy.

4. Curved Fish’s Spine

As the fish’s muscles and tissues deteriorate, the straight, blue-colored line on my neon tetras will distort into an “S” shape. The fish’s tail will also bend downward.

5. Secondary Infections

Infected fish may also develop other infections such as bloating and fin rot. Neon tetra disease weakens the fish’s immune system, leaving it vulnerable to other infections.

Also Read: 17 Neon Tetra Diseases & Their Treatments

False Neon Tetra Disease

Did you know there is a condition known as false neon tetra disease? It’s actually called columnaris and exhibits very similar symptoms to neon diseases.

The main indicators of columnaris are white spots on the fish’s body. These white spots resemble the white cysts seen in sick neon tetras.

Fortunately, columnaris can be treated with a course of antibiotics. Additionally, this disease has milder effects compared to neon tetra disease.

You can watch this YouTube video for further explanation on the causes and treatment for Columnaris:

Treating Neon Tetra Disease

Currently, there is no effective medication available to treat neon tetra disease.

Once you observe the signs, it is crucial to remove all affected fish to prevent the infection from spreading throughout the tank.

Certain fish medications can provide temporary relief by preventing further infections, but they do not cure this fatal disease.

It may take weeks or even months before my neon tetras succumb to the disease. Many aquarium enthusiasts choose to euthanize sick fish to alleviate their suffering.

If euthanizing your fish is not an option, I can try the following:

1. Antibacterial Treatment

Although neon tetra disease mimics the symptoms of a bacterial infection, attempting antibacterial treatment is not harmful.

This treatment helps eliminate bacterial contaminants in the aquarium water and treats bacterial infections in the fish.

However, it’s important to note that antibacterial treatment is only effective against bacterial infections, not neon tetra disease.

If your fish recover after this treatment, it means they were suffering from false neon tetra disease.

2. Medicated Bath

Another option is to bathe your sick fish in methylene blue for ten days to eliminate parasitic infections.

This medicated bath offers several benefits, including treating open sores that make the fish susceptible to further tissue infections.

It also promotes faster healing by enhancing osmoregulation, preventing bacterial growth, and improving oxygen absorption in the tissues.

However, it’s essential to avoid overdosing on methylene blue, as it can destroy the beneficial bacteria in the tank.

Also Read: Growth on Neon Tetra’s Mouth

Preventing Neon Tetra Disease

When it comes to neon tetra disease, prevention is better than treatment. Here are some preventive measures I can take to avoid neon tetra disease:

1. Do Not Purchase Sick Fish

Before purchasing fish, it’s important to carefully inspect their condition at the pet store. If neon tetras do not appear healthy, it’s best to refrain from bringing them home.

Some signs of sick neon tetra fish include pale coloration and lack of schooling with other tetras.

2. New Fish Isolation

When you bring home new fish that appear lively and vibrant, it’s important to refrain from immediately adding them to the communal tank.

Instead, provide them with their own separate isolation tank for up to two weeks. This allows you to carefully observe any potential diseases or parasites they may carry.

Also, remember to isolate new plants before introducing them to the main fish tank.

3. Purchase Live Food From Reliable Sources

Living feeds like tubifex can sometimes transmit parasitic organisms that cause neon tetra disease.

Therefore, it is always advisable to obtain your live feeds from trustworthy pet shops.

Alternatively, consider feeding your neon tetras fish flakes, as they carry a lower risk of infection transmission.

4. Isolate Diseased Fish

Given the rapid spread of neon tetra disease, it is crucial to promptly remove any affected neon tetras from the tank to prevent further spread.

Relocate them to a separate recovery tank.

5. Maintain A Clean Habitat

Neon tetras thrive in an aquarium environment with plants and driftwood.

Unfavorable water conditions can promote the growth of harmful pathogens, and these fish are particularly susceptible to infections if the tank water is not kept clean.

To ensure a healthy tank environment, follow these guidelines:

  • Weekly Tank Cleaning
  • Thoroughly cleaning the tank at least once a week.
  • Remove fish waste, leftover food, deceased fish, and decaying plant matter.
  • Vacuum the substrate and clean the tank walls using filter floss. While this cleaning routine may take up to two hours, it is crucial for the well-being of your fish.
  • Regular Water Changes.

Weekly water replacement is also essential. Change approximately 10 to 20% of the aquarium’s water.

The fresh water should have a similar temperature and hardness to the existing tank water to prevent thermal shock.

Moreover, avoid pouring tap water directly into the tank due to its chlorine and chloramine content.

Although harmless to humans, these substances can harm your tank’s beneficial bacteria colonies and your neon tetra’s gills.

  • Routine Water Testing

Regular water tests are important for monitoring the water conditions in your aquarium. Monitor the levels of ammonia, nitrites, and nitrates.

Ideally, both ammonia and nitrite levels should read 0 ppm. Since neon tetras are freshwater fish, nitrate levels should be around 10 ppm.

Also, ensure that the pH level is within the range of 6.5 to 7.5 and the carbonate hardness level remains between 1 and 2 dKH.

  • Filter Media Replacement

Filters play a crucial role in keeping the tank clean and healthy by removing waste, debris, and ammonia buildup. However, they also require maintenance.

Filter components and media can potentially harbor harmful bacteria. Therefore, rinse the filters every two weeks and replace the components as needed.

When doing so, use treated water to avoid killing the beneficial bacteria.

  • Incorporate UV Sterilizers

UV sterilizers can effectively control the proliferation of algae, bacteria, and other microorganisms in both freshwater and saltwater aquariums.

While aquarium filters purify the tank water, they do not eliminate microorganisms. UV sterilizers expose these parasites and organisms to radiation, preventing their multiplication.

Additionally, UV sterilizers can clarify green water, making it easier to detect waste. They also enhance the redox balance, thereby boosting the immune system of neon tetras.

6. Sanitize The Community Tank

If your neon tetras show signs of disease, it is crucial to clean the main tank to eliminate parasites and prevent further infections. Here is a step-by-step guide to cleaning the tank:

  • Prepare a solution by mixing one part bleach with eight parts water.
  • Use this bleach solution to disinfect the tank and its equipment.
  • Let it sit for 20 minutes.
  • Rinse the aquarium thoroughly.
  • Allow the tank to dry naturally for a day.
  • Fill the tank with de-chlorinated water and let it sit for two hours.
  • Drain the water and refill the tank with fresh de-chlorinated water.
  • Complete the nitrogen cycle.
  • Only after the tank is fully cycled, add new fish to it.
  • Remember to isolate new fish before introducing them to the main tank.

Also Read: Neon Tetra Ich (White Spot)

How Long Does It Take For Infected Fish To Die From Neon Tetra Disease?

The lifespan of a sick neon tetra after infection can range from weeks to months.

Factors such as tank conditions, stress, and overall health significantly influence the duration a neon tetra can survive after being infected.

Is Neon Tetra Disease Contagious?

Yes, neon tetra disease can spread if an infected fish comes into close contact with healthy ones, or if aquarium fish consume the remains of infected fish.

The transmission can occur within a few hours or days.

Do All Neon Tetras Carry This Disease?

No, not all neon tetras carry this disease. While it was initially identified in neon tetras, other decorative fish can also be affected.

Cardinal tetras, for example, are relatively resistant to neon tetra disease but can still be susceptible to it.

Does Neon Tetra Disease Affect Humans?

No, neon tetra disease can be fatal to neon tetras and other fish species but is harmless to humans.

Is Neon Tetra Disease The Same As Cardinal Tetra Disease?

Yes, neon tetra disease closely resembles cardinal tetra disease, and they share the same symptoms.

Cardinal tetras have a certain level of resistance to the disease, but they are not completely immune.


Neon tetra disease is a progressive condition that affects neon tetras and other tank mates. It damages the fish’s tissues, muscles, and organs, ultimately leading to fatality.

The disease spreads through the consumption of infected dead fish or diseased live food. The good news is that this disease can be prevented.

Therefore, always isolate new fish and plants, purchase high-quality live food from reputable pet shops, and maintain a clean environment for your neon tetras to enjoy a long and healthy life.