17 Neon Tetra Diseases & Their Treatments: A Complete Guide

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I enjoy keeping neon tetras in my tank. Let’s face it, these fish are extremely beautiful and easy to care for. However, when they get sick, it’s my responsibility to take care of them.

Unfortunately, diagnosing illnesses in fish and selecting the appropriate treatment can be challenging, particularly for neon tetras due to their small size.

That’s why I have created this guide, which covers 17 diseases that can affect neon tetras and provides the proper approach for each one. Let’s dive in.

Also Read: Neon Tetra Care Guide

1. White Spot Disease/Ich

White Spot Disease, commonly known as “Ich,” is a widespread parasitic disease caused by the protozoan Ichthyophthirius multifiliis.

In Neon Tetras, the disease manifests as white spots on the body and fins.

How To Treat White Spot Disease

To treat ich, follow these four steps:

Increase the aquarium temperature: Gradually elevate the temperature to 78-80°F over 48 hours. Higher temperature speeds up the parasite’s life cycle, helping treatments work more effectively.
Administer medication: Use a commercial anti-ich medication following the manufacturer’s instructions. Products containing formalin and malachite green are often effective. My recommendation: Fritz Mardel (link to Amazon).
Maintain good water quality: Perform regular water changes and keep the aquarium clean. Remove any dead or severely infected fish to avoid further spreading of the parasite.
Maintain treatment: Continue the treatment for at least a week or until all signs of the infection are gone, even if the fish appear to be better.

How To Prevent Ich

Quarantine new fish: Always quarantine new arrivals for about 2 weeks before introducing them to your main tank. This gives you time to observe them for any signs of disease.
Maintain optimal water conditions: Ensure your aquarium has proper filtration and that you’re doing regular water changes. Stress from poor water quality can make fish more susceptible to diseases like Ich.
Feed a balanced diet: High-quality, varied diet helps to keep fish’s immune system strong and more capable of warding off infections.

Also Read: Neon Tetra Ich (White Spot)

2. Fin And Tail Rot

Fin and Tail Rot is a bacterial disease often observed in aquarium fish, including Neon Tetras. It is usually caused by bacteria named Pseudomonas and Aeromonas.

It causes progressive damage to the fins and tail, starting as frayed, discolored edges and, if left untreated, can lead to complete destruction of the fins.

How To Treat Fin Or Tail Rot

To treat affected fish, follow these steps:

Isolate infected fish: If possible, move the infected fish to a separate quarantine tank. This can prevent the disease from spreading to healthy fish.
Improve water quality: Perform regular water changes and monitor the water conditions in your tank. Unhealthy water conditions can stress fish and make them more susceptible to disease.
Administer antibiotics: Use a commercial antibacterial medication specifically designed for treating fin and tail rot. My recommendation: API MELAFIX (link to Amazon).
Monitor and repeat treatment: Keep a close eye on the fish during treatment. If you don’t see improvement within five to seven days, you may need to repeat the treatment.

Also Read: Neon Tetra Fin Rot

3. Swollen Gills

Swollen gills in neon tetras is a condition that is often a sign of a more significant underlying problem, typically related to water quality or parasitic infections.

The condition can result in the fish’s gills appearing visibly enlarged or protruding from under the gill cover.

How To Treat Swollen Gills

If your neon tetras are gasping for air, follow these steps:

Identify the Problem: Look for the signs of swollen gills, which may include red, inflamed, or protruding gills.
Quarantine the Affected Fish: If possible, move the sick fish to a separate quarantine tank. This can help prevent potential diseases from spreading to other fish in your main tank.
Water Quality Check: Test the water conditions in your aquarium, including temperature, pH, and levels of ammonia, nitrite, and nitrate. Poor water quality is often a primary cause of gill issues in fish.
Water Change: Perform a significant water change to help improve water conditions. Ensure that the new water is dechlorinated and matches the existing water’s temperature.
Medication: Depending on the cause of the swollen gills, treatment may include anti-parasitic medication, antibacterial treatment, or medication to remedy potential fungal infections. Always follow the manufacturer’s instructions when using any medication.
Monitor and Repeat: Continuously monitor the affected fish, and continue to change the water and administer medication as directed until the condition improves. If the fish’s condition does not improve or worsens, consult a vet specializing in fish diseases.

4. Swim Bladder Disorder

Swim bladder disorder is a common issue among fish, including neon tetras, that affects their buoyancy.

The swim bladder is an internal organ filled with gas that helps fish maintain their depth in the water.

When this organ becomes impaired, it can lead to symptoms such as the fish swimming sideways, upside down, or having difficulty rising or sinking in the water column.

How to Treat Swim Bladder Disorder

Identify the Problem: Signs of swim bladder disorder include irregular swimming, difficulty maintaining equilibrium, floating upside down, sinking to the bottom of the tank, or struggling to rise to the top.
Quarantine the Affected Fish: If possible, move the sick fish to a separate tank to prevent any potential spread of disease, even though swim bladder disorder is typically not contagious.
Fasting: Give the fish a short period of fasting for about 24-48 hours. This can help to clear its digestive system, which might be impacting the swim bladder.
Feeding: After the fasting period, feed the fish a diet of easy-to-digest foods, like daphnia or cooked and peeled peas, which can help relieve constipation, a common cause of swim bladder disorder.
Water Change: Conduct a partial water change to ensure clean and stress-free conditions. Stress and poor water quality can exacerbate swim bladder disorder symptoms.
Monitor: Keep a close eye on the affected fish and its progress. If there’s no improvement or if the condition worsens, consult a vet specializing in fish diseases.

Also Read: Neon Tetra Swim Bladder Disease

5. Columnaris & Mouth Fungus

Columnaris, also known as cotton wool, mouth fungus, or saddleback, is a common bacterial disease in aquarium fish, including neon tetras.

Despite its common name, mouth fungus, it’s not a fungal infection but is caused by the bacterium Flavobacterium columnare.

How To Treat Columnaris & Mouth Fungus

Early detection is crucial for effective treatment. Consider the following options:

Identify the Problem: Look for signs such as white or grayish patches on the body, gills, or mouth, frayed fins, ulcers, loss of appetite, rapid gill movement, and lethargy.
Quarantine the Affected Fish: If possible, isolate the sick fish in a hospital tank to prevent the spread of the disease to other tank mates.
Water Quality Check: Test the water parameters. Columnaris often occurs in tanks with poor water quality, especially those with high nitrate levels and excessively warm temperatures.
Water Change: Perform a significant water change to improve water conditions. The new water should be dechlorinated and match the existing water’s temperature.
Medication: Treat the disease using a broad-spectrum antibiotic like Kanamycin or treatments specifically designed for columnaris, following the manufacturer’s instructions. My recommendation: API MELAFIX (link to Amazon).
Monitor and Repeat: Monitor the affected fish, continue to change the water, and administer medication as directed until the condition improves. If the fish’s condition worsens or does not improve, consult a vet specializing in fish diseases.

How To Prevent Columnaris & Mouth Fungus

Prevention of columnaris disease is largely about maintaining good water quality and reducing stress for your fish. Regularly monitor and maintain optimal water parameters.

Also Read: Growth On Neon Tetra’s Mouth

6. Velvet (Oodinium)

Velvet, also known as gold dust disease, is a common parasitic disease in aquarium fish, including neon tetras.

It’s caused by the dinoflagellate parasite, typically Oodinium pilularis in freshwater species.

How To Treat Velvet

To treat velvet:

Identify the Problem: Look for signs such as a gold or rust-colored dust on the fish’s body, rubbing against objects, clamped fins, rapid gill movement, loss of appetite, and lethargy.
Quarantine the Affected Fish: If possible, move the sick fish to a quarantine tank. Velvet is highly contagious, so separating the affected fish can help prevent the disease from spreading.
Dim Lighting: The parasites causing velvet are photosynthetic, so reducing light levels can inhibit their growth.
Medication: Treat with a copper-based medication or other antiparasitic treatment designed for velvet, following the manufacturer’s instructions. My recommendation: Fritz Mardel (link to Amazon).
Raise the Water Temperature: Slightly raising the water temperature (without exceeding the safe range for your species of fish) can speed up the lifecycle of the parasite and enhance the effectiveness of the treatment.
Monitor and Repeat: Monitor the affected fish, and continue to change the water and administer medication as directed until the condition improves. If the fish’s condition worsens or does not improve, consult a vet specializing in fish diseases.

How To Prevent Velvet

Preventing velvet disease primarily involves maintaining a clean and stress-free environment for your fish.

Regularly check and adjust water conditions to ensure they are within optimal parameters for your fish species.

Also Read: Stress In Neon Tetras

7. Neon Tetra Disease (NTD)

Neon Tetra Disease (NTD) is a serious, often fatal condition specifically affecting neon tetras and closely related species.

It’s caused by a microsporidian parasite, Pleistophora hyphessobryconis.

How To Treat Neon Tetra Disease

Identify the Problem: Symptoms of NTD include faded or patchy coloration, lumps or cysts on the body, an uneven swimming pattern, a bent spine, lethargy, and a refusal to eat.
Quarantine the Affected Fish: Neon Tetra Disease is contagious and can quickly spread through your tank. If you suspect a fish has NTD, remove it from the main tank and place it in a separate quarantine tank immediately.
Euthanasia: Unfortunately, there is no known cure for NTD. If a fish is severely suffering and shows advanced symptoms of the disease, humane euthanasia may be the kindest option.

Also Read: Neon Tetra Disease

8. Popped Eyes

Popped eyes, also known as exophthalmia or pop-eye, is a condition in which one or both eyes of the fish bulge outwards.

This often indicates an underlying condition such as a bacterial infection, parasitic infestation, or poor water quality.

How To Treat Popped Eyes

Follow these steps to treat pooped eyes disease:

Identify the Problem: Look for signs such as bulging or protruding eyes. There might also be other accompanying signs like lethargy, loss of appetite, or changes in swimming behavior.
Quarantine the Affected Fish: If possible, isolate the sick fish in a hospital tank. This can prevent the spread of potential infectious diseases and also allow for more effective treatment.
Water Quality Check: Test the water parameters in your aquarium. Poor water quality is often a significant cause of popped eyes.
Water Change: Perform a significant water change in the affected fish’s tank. Improving the water quality can often help in the recovery process.
Medication: Depending on the cause of the popped eyes, treatment may include antibiotics or anti-inflammatory medications. My recommendation: API MELAFIX (link to Amazon).
Monitor and Repeat: Continuously monitor the affected fish, and continue to change the water and administer medication as directed until the condition improves. If the fish’s condition does not improve or worsens, consult a vet specializing in fish diseases.

9. Camallanus Internal Worm

Camallanus worms are internal parasites that affect fish, including neon tetras.

They are a type of nematode worm that resides in the intestines of fish, causing damage and potentially severe illness.

How To Treat Camallanus Internal Worm

To treat this condition:

Identify the Problem: Watch for symptoms such as weight loss, reduced activity, lack of appetite, and red worms visibly protruding from the fish’s anus.
Quarantine the Affected Fish: Move the affected fish to a quarantine tank to prevent the spread of the parasites.
Medication: Administer an anti-parasitic medication that is effective against nematodes, like Levamisole or Fenbendazole, following the manufacturer’s instructions. My recommendation: Hikari Prazipro (link to Amazon).
Water Change: After treatment, perform a thorough water change and clean the substrate to remove any remaining eggs or larvae. Repeat this process several times to ensure all parasites are eliminated.
Retreatment: Repeat the treatment after a few weeks to ensure that all parasites, including those that may have hatched from eggs post-treatment, are eliminated.
Monitor: Continuously monitor the affected fish, and if the fish’s condition does not improve or worsens, consult a vet specializing in fish diseases.

10. Viral Hemorrhagic Septicemia (VHS)

Viral Hemorrhagic Septicemia (VHS) is a highly contagious and deadly viral disease that affects fish, including neon tetras.

It is caused by the VHS virus, which can result in significant fish losses in freshwater and marine environments.

How To Treat Viral Hemorrhagic Septicemia

To deal with this condition follow these steps:

Identify the Problem: Look for symptoms such as abnormal swimming, hemorrhages, bloated body, pale gills, and rapid, unexplained deaths among your fish.
Quarantine the Affected Fish: As VHS is highly contagious, it’s essential to isolate sick fish in a separate hospital tank immediately.
No Known Cure: Unfortunately, there is no known cure for VHS. Treatment generally focuses on maintaining water quality and reducing stress on fish, which can help to slow the spread and impact of the virus.
Euthanasia: In severe cases, where fish are suffering significantly, euthanasia may be the most compassionate course of action.

11. Black Spot Disease

Black spot disease, also known as diplopstomiasis or fluke disease, is a parasitic disease that affects fish, including neon tetras. It’s caused by a type of digenetic fluke.

How To Treat Black Spot Disease

To treat black spot disease, follow these steps:

Identify the Problem: Look for signs such as tiny black or dark grey spots on the fish’s body, flashing, and rubbing against objects.
Quarantine the Affected Fish: If possible, isolate the sick fish in a separate tank to prevent the parasites from spreading to other fish.
Medication: Treat the disease with a medication specifically designed to eliminate flatworms. My recommendation: Hikari Prazipro (link to Amazon).
Water Change: After the treatment, conduct a significant water change and clean the substrate to remove any remaining parasites or eggs.
Retreatment: Repeat the treatment after a week to ensure that all parasites, including those that may have hatched from eggs post-treatment, are eliminated.
Monitor: Continuously monitor the affected fish. If the fish’s condition does not improve or worsens, consult a vet specializing in fish diseases.

Also Read: Black Spots On Neon Tetras

12. Scoliosis (Bent Spine)

Scoliosis is a rare condition that can affect neon tetras. It can be attributed to genetics or environmental factors. Fortunately, this disease is not contagious but inherited from parents.

How To Treat Scoliosis

Follow these steps to deal with Scoliosis in neon tetras:

Identify the Problem: Look for symptoms such as a visibly curved or bent spine and changes in swimming behavior.
Quarantine the Affected Fish: If possible, isolate the sick fish in a hospital tank to monitor its condition closely and prevent potential spread of any underlying diseases.
Nutritional Adjustment: If the scoliosis is due to nutritional deficiency, provide a balanced diet rich in vitamins, especially vitamin C.
Medication: If the scoliosis is due to an underlying disease or infection, treat the disease accordingly with appropriate medication.
Supportive Care: Provide a stress-free environment and ensure optimal water conditions to support the fish’s overall health.
Veterinary Consultation: If the condition does not improve, consider consulting with a veterinarian specializing in fish diseases.

13. Fish Tuberculosis

Fish Tuberculosis (TB) or Mycobacteriosis is a chronic, often fatal disease affecting fish, including neon tetras. It’s caused by bacteria from the Mycobacterium genus.

How To Treat Tuberculosis

Follow these steps to deal with tuberculosis in neon tetras:

Identify the Problem: Watch for signs such as loss of appetite, weight loss, loss of color and scales, ulcers, and abnormal behavior.
Quarantine the Affected Fish: Fish TB is contagious and can quickly spread throughout your tank. If you suspect a fish has Fish TB, it should be isolated immediately.
Consult a Veterinarian: As Fish TB is a zoonotic disease (can be transmitted to humans), it’s essential to handle infected fish with care and consult a vet for appropriate diagnosis and treatment options.
Treatment: Medications like kanamycin combined with Vitamin B6, or anti-tubercular drugs can be used under the supervision of a vet. However, treatment is often unsuccessful if the disease is advanced.

14. Hexamitiasis

Hexamitiasis is a parasitic disease that commonly affects freshwater fish, including neon tetras. It’s caused by the flagellate protozoan parasite, Hexamita.

How To Treat Hexamitiasis

Follow these steps if you think that your neon tetra caught Hexamitiasis:

Identify the Problem: Symptoms to look out for include loss of appetite, lethargy, white and stringy feces, emaciation, and, in some cases, lesions on the head.
Quarantine the Affected Fish: If possible, isolate the sick fish in a separate quarantine tank to prevent the spread of the parasites.
Medication: Treat the infected fish with an anti-protozoal medication, such as Metronidazole, following the manufacturer’s instructions.
Water Change: After the treatment, perform a significant water change and clean the substrate to remove any remaining parasites or eggs.
Retreatment: Repeat the treatment after a week to ensure that all parasites, including those that may have hatched from eggs post-treatment, are eliminated.
Monitor: Continuously monitor the affected fish. If the fish’s condition does not improve or worsens, consult a vet specializing in fish diseases.

15. Constipation

Constipation in fish, including neon tetras, is a common issue often caused by a diet that’s low in fiber or too much dried food.

How To Treat Constipation

To treat constipation in neon tetras, follow these steps:

Identify the Problem: Look for signs such as a bloated abdomen, difficulty swimming, and lack of fecal production.
Fasting: Start by not feeding your fish for a couple of days. This can often help to clear any blockage.
Dietary Change: Following the fasting period, feed your fish a diet high in fiber. Daphnia, peas (with shells removed), and brine shrimp are good choices that can act as a natural laxative.
Increased Temperature: Slightly increasing the water temperature (no more than a couple of degrees) can sometimes help speed up digestion.
Monitor: Monitor your fish closely during this time. If symptoms persist despite these steps, or if the fish’s condition worsens, consult with a vet specializing in fish diseases.

Also Read: Neon Tetra Constipation

16. Gill Flukes

Gill Flukes, caused by a parasitic flatworm (Dactylogyrus spp. in freshwater fish), is a common disease in fish including neon tetras.

These tiny parasites attach to the gills of the fish, causing irritation and breathing difficulties.

How To Treat Gill Flukes

Follow these steps to treat a neon tetra with gill flukes:

Identify the Problem: Watch for signs such as rapid gill movement, excessive mucus, loss of color, lethargy, and unusual behavior such as rubbing against objects.
Quarantine the Affected Fish: If possible, move the affected fish to a separate quarantine tank to prevent the spread of the parasites.
Medication: Treat the fish with a medication designed to eliminate gill flukes. My recommendation: Hikari Prazipro (link to Amazon).
Water Change: After the treatment, conduct a thorough water change and clean the substrate to remove any remaining parasites or eggs.
Retreatment: Repeat the treatment after a week to ensure that all parasites, including those that may have hatched from eggs post-treatment, are eliminated.
Monitor: Continuously monitor the affected fish. If the fish’s condition does not improve or worsens, consult a vet specializing in fish diseases.

17. Dropsy

Dropsy is a serious disease in fish, including neon tetras, often associated with a bacterial infection.

It causes fluid accumulation inside the fish, leading to a swollen, pinecone-like appearance.

How To Treat Dropsy

Follow these steps:

Identify the Problem: Look for symptoms such as a bloated body, scales sticking out (giving a pinecone-like appearance), loss of appetite, lethargy, and changes in color.
Quarantine the Affected Fish: If you notice a fish showing signs of dropsy, quarantine it in a separate tank to prevent potential spread of any underlying disease.
Antibacterial Treatment: Treat the fish with a broad-spectrum antibacterial medication such as Kanamycin or Maracyn-Two, following the manufacturer’s instructions.
Epsom Salt Bath: Epsom salt baths can sometimes help draw out some of the excess fluid in the fish. Dissolve 1-3 teaspoons of Epsom salt per gallon of water in a separate container. Allow the fish to soak there for 15-20 minutes.
Monitor: Keep a close watch on the affected fish.

How To Prevent Neon Tetra Diseases

Neon tetras are generally resilient fish, and most diseases can be prevented by following these guidelines:

Maintain Water Quality: Keep the tank’s pH between 6.0 and 7.0, the temperature between 72°F and 80°F, and ammonia and nitrite levels at 0 ppm. Regularly test your water to ensure these conditions.
Feed Appropriate Amounts: Provide a variety of high-quality fish food, enough that your neon tetras can consume within 2 minutes, typically once or twice a day. Overfeeding can lead to water contamination and obesity.
Practice Good Maintenance Habits: Perform regular water changes, typically 25-50% of the tank volume every week, to prevent buildup of harmful chemicals. Keep your tank equipment clean and functioning properly.
Inspect Your Fish: Regularly observe your fish for signs of illness such as lethargy, discoloration, bloating, or erratic swimming. Early detection can help prevent the spread of disease.
Quarantine New Fish And Decorations: Keep new additions in a separate tank for 2-4 weeks before introducing them to your main tank. This allows time to monitor for potential diseases or parasites.
Reduce Stress: Avoid rapid changes in water conditions, overcrowding, or aggressive tank mates. A stable, peaceful environment will boost your neon tetras’ immune systems and make them less susceptible to diseases.

Also Read: Neon Tetra Eggs 101

Conclusions

Maintaining optimal water conditions can prevent most of the diseases mentioned above, which is excellent news.

However, if you suspect that your neon tetra is ill, the first step is to quarantine the fish to prevent infection of others and perform a water change.

Following this, it is highly recommended to consult an aquatic vet for further guidelines.