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Stress In Neon Tetras: 15 Symptoms And Solutions

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Neon tetras are beautiful and peaceful, which is why many fish owners choose to raise and breed them in their tanks.

However, like any other fish, they can become stressed for various reasons. Unfortunately, identifying the underlying cause can be challenging.

That’s why I decided to write this article.

Here, I will discuss 15 common symptoms of stressed neon tetras and provide detailed instructions on how to address each one. Let’s dive right in.

Also Read: Neon Tetra Care Guide

1. Gasping Near the Water Surface

Neon tetras gasping at the water’s surface indicates a lack of oxygen.

Pollutants like ammonia or nitrite can impair gill function, similar to humans struggling to breathe in smoky or noxious environments.

pH crashes and Acidosis can also cause similar symptoms.

Checking water quality and temperature, increasing aeration, and reviewing stocking levels are essential to address the issue.

How To Treat

  • Assess the water quality: First, test your aquarium water for high levels of ammonia, nitrite, and nitrate. These substances, when present in excess, can cause distress in fish, leading them to gasp for air at the surface.
  • Increase the oxygen level: Introduce an air stone or increase the water flow from the filter to improve oxygenation. A lack of oxygen can cause neon tetras to gasp for air near the water surface.
  • Lower the temperature: Consider lowering the temperature in the tank slightly, as cooler water holds more oxygen. Neon tetras prefer a temperature range between 70°F and 81°F (21°C-27°C).
  • Review stocking levels: Overcrowding in an aquarium can cause stress and reduce oxygen levels. Ensure that your aquarium is not overstocked.

Also Read: Why Is My Neon Tetra Gasping For Air?

2. Loss of Appetite

Neon tetras may lose their appetite due to various reasons.

Pregnancy can cause reduced appetite in egg-carrying fish, while illness can lead to a loss of interest in food.

Stress from tank changes or the addition of new tank mates can also affect their eating habits.

How To Treat

  • Check water parameters: Again, start by checking your water quality. Fluctuations in pH, temperature, and chemical levels can lead to stress and appetite loss.
  • Change the diet: Try to vary the diet of your tetras. Incorporating a range of flake foods, freeze-dried foods, and live or frozen foods can help stimulate appetite.
  • Reduce stress: Keep the aquarium in a calm and quiet place to minimize stress from external factors. Excess noise and vibrations can cause stress and result in a loss of appetite.

Also Read: Why Is My Neon Tetra Not Eating?

3. Engaging in Glass Surfing

Neon tetras may swim up and down the glass of their aquarium, a behavior known as glass surfing, due to stress.

Factors such as poor water conditions, overstocking, incompatible tank mates, and inadequate tank size can contribute to neon tetras feeling stressed in their environment.

How To Treat

  • Check for reflections: Neon tetras can sometimes be agitated by their reflections in the glass. Consider reducing tank lighting or adding a background to the aquarium to minimize reflections.
  • Modify the environment: Add plants, caves, or other forms of enrichment to the aquarium. A lack of environmental complexity can lead to boredom and resultant glass-surfing behavior.
  • Evaluate companions: Glass surfing can also be a sign of bullying or harassment from other fish. Ensure that your tetras are kept with compatible tank mates.

4. Twitching and Shivering

Neon tetras may twitch or shake due to various reasons, including courtship behavior, underlying health issues, incorrect water chemistry, cold temperatures, and stress.

Proper diagnosis and treatment are essential to address the specific cause of the twitching behavior and ensure the well-being of the fish.

How To Treat

  • Examine for disease: Twitching and shivering can indicate an underlying illness. Look for other signs of disease, such as discoloration, clamped fins, or white spots.
  • Isolate if necessary: If you suspect a disease, quarantine the affected tetras immediately to prevent the spread of the disease.
  • Consult a vet: Seek professional advice if you can’t identify the cause of the twitching and shivering. Your fish may require medication.

Also Read: Why Do Neon Tetras Twitch?

5. Seeking Refuge and Hiding

Neon tetras may hide due to their natural prey instincts as smaller fish. They seek hiding places when uncertain, stressed, or uncomfortable.

Reasons for hiding include newcomers in the tank, bullying by aggressive fish, loneliness, lack of hiding spaces, environmental changes, and overcrowding.

How To Treat

  • Assess the light levels: Excessive lighting can lead neon tetras to seek refuge in shaded areas. Ensure that your aquarium lighting replicates a natural day-night cycle.
  • Provide adequate hiding spots: Add plants, rocks, and caves to provide more hiding spots. This can make your tetras feel more secure and less likely to hide persistently.
  • Monitor the behavior of other fish: Persistent hiding can be a sign of harassment from other fish. Observe the interactions of your fish to ensure there are no signs of aggression.

Also Read: Why Do My Neon Tetras Keep Hiding?

6. Fading of Colors

Neon tetras may lose their color due to factors such as poor water quality, inadequate oxygenation, temperature fluctuations, stress, improper diet, and illness.

How To Treat

  • Inspect for illness: Fading colors can be a symptom of stress or disease. Look for other signs of illness such as lethargy, changes in eating habits, or abnormal behavior.
  • Optimize diet: Ensure that your tetras are getting a balanced diet, rich in vitamins and minerals. Diet directly impacts the vibrancy of a fish’s colors.
  • Ensure suitable environment: Make sure the tank conditions, including temperature, pH, and hardness, are optimal for neon tetras. Unsuitable conditions can lead to stress and color loss.

Also Read: Why Is My Neon Tetra Turning White?

7. Chasing and Harassing Other Fish

Neon tetras may chase other fish for various reasons, including defending their territory, establishing dominance, competing for food and mates, and experiencing constant stress.

Factors such as incompatible tank mates, poor water conditions, and overcrowding can contribute to this behavior.

How To Treat

  • Check tank size and companions: Make sure your tank is big enough for the number and species of fish you have. Also, ensure that all species are compatible.
  • Increase the number of tetras: Neon tetras are schooling fish. They can display aggressive behaviors if they are in a group of fewer than 6. Increasing the school size can alleviate this behavior.
  • Create territories: Use rocks, plants, and decorations to create separate territories. This can help reduce aggression between fish.

8. Deterioration and Degradation of Fins

Neon tetras’ fins can deteriorate due to various factors. One common cause is poor water conditions, which weaken their immune system and make them more susceptible to fin rot.

Stressful conditions, such as overcrowding or being chased by aggressive fish, can also contribute to fin deterioration.

How To Treat

  • Look for signs of fin rot: Fin rot is a common disease in aquarium fish that causes the fins to degrade. If you see signs of fin rot, begin treatment immediately with an over-the-counter antibiotic.
  • Check for aggressive tank mates: Some fish species are known for fin nipping. If you notice this behavior, separate the aggressor immediately.
  • Maintain water quality: Good water quality is key to fin health. Regular water changes, testing, and maintaining proper parameters can prevent many fin issues.

Also Read: Neon Tetra Diseases

9. Rubbing Against Gravel or Decorations

Neon tetras may rub against rocks and other objects in the aquarium for several reasons. It can be a natural behavior as they establish dominance or prepare to mate.

Additionally, the fish may be trying to relieve itching caused by parasites, fungal infections, or stress.

How To Treat

  • Inspect for external parasites: This behavior, also known as “flashing,” is often a sign of irritation caused by external parasites. If suspected, treat your fish and aquarium with an anti-parasite medication.
  • Check water parameters: Abrupt changes in water conditions can cause discomfort, leading fish to scratch themselves against objects.
  • Ensure appropriate decor: Make sure the decorations in your tank don’t have sharp edges that could potentially hurt your fish.

Also Read: 15 Things You Should Know About Neon Tetras

10. Turning Black

Neon tetras turning black is usually a sign of poor health or stress. High ammonia levels and subsequent ammonia poisoning can cause black patches to develop.

Other reasons include nitrite poisoning, fin rot, and black spot disease.

How To Treat

  • Assess for black neon tetra disease: If your fish are turning black, they may have contracted this disease. Quarantine affected fish immediately, and consider consulting a vet for treatment options.
  • Check water quality: Poor water conditions can lead to stress, which can cause color changes in neon tetras. Maintain a regular schedule of water changes and testing to ensure optimal water conditions.
  • Balance diet: A balanced and varied diet can help maintain the vibrant colors of your neon tetras. Include high-quality flake food, live, or frozen foods in their diet.

Also Read: Why Is My Neon Tetra Turning Black?

11. Lack of Movement

Neon tetras may not move due to various reasons. It could be because they are resting or sleeping, which is normal behavior.

If they are being chased or stressed by other fish, they may hide or stay still. Poor water quality, including high levels of ammonia or nitrite, can also cause stress and immobility.

Additionally, if a fish is sick or affected by a disease, it may become lethargic and stay at the bottom of the tank.

How To Treat

  • Check for disease: Lack of movement can be a sign of illness. Observe your fish for other symptoms such as loss of appetite, discoloration, or breathing difficulties.
  • Ensure optimal water parameters: Tetras may become lethargic if the water temperature, pH, or hardness is not within their preferred range.
  • Monitor feeding patterns: Overfeeding can lead to lethargy. Ensure that you’re not overfeeding your fish, and they’re getting a balanced diet.

Also Read: Why Is My Neon Tetra Not Moving?

12. Staying at the Bottom

Neon tetras may lay at the bottom of the tank for various reasons. It could be because they are bottom-dwelling fish, resting, or exploring the lower levels of the aquarium.

However, if accompanied by red flags such as lack of appetite, labored breathing, or loss of buoyancy control, it may indicate stress, illness, or poor water quality.

How To Treat

  • Check for swim bladder disease: Fish that spend most of their time at the bottom of the tank may have swim bladder disease. If suspected, consult a vet or pet professional for treatment options.
  • Monitor water quality: Poor water quality can lead to stress, causing fish to rest at the bottom. Regular water changes and testing can help maintain optimal water conditions.
  • Provide a varied diet: Some fish might stay at the bottom if their diet is not varied enough. Introduce a mix of foods to stimulate their interest.

Also Read: Why Do My Neon Tetras Stay At The Bottom Of The Tank?

13. Staying at the Top

Neon tetras may stay at the top of the tank due to various reasons. It could be a normal behavior such as sleeping, exploring, or responding to changes in the tank.

However, it could also indicate concerning issues like lack of oxygen, disease, stress, or extreme water temperature.

How To Treat

  • Increase oxygen levels: If your fish are staying at the top of the tank, they might be trying to access more oxygen. Introduce an air stone or increase the water flow from the filter to enhance oxygenation.
  • Check water parameters: Like with most problems, poor water conditions could be causing this behavior. Regularly check your water parameters to ensure they are suitable for neon tetras.
  • Check for diseases: Fish diseases can lead to unusual behaviors. If your tetras are spending a lot of time at the top, examine them for signs of illness.

Also Read: Neon Tetras Staying At The Top Of The Tank

14. Blowing Bubbles Persistently

Neon tetras may blow bubbles in the aquarium for various reasons.

Bubbles can be a normal occurrence, such as when using air-driven filters or air stones, or when aquatic plants undergo photosynthesis, producing oxygen.

However, excessive bubble production can indicate water quality issues, lack of oxygen, stress, or a need for cleaning.

How To Treat

  • Evaluate the water quality: Tetras might blow bubbles as a response to poor water quality. Make sure to conduct regular water tests to maintain optimal conditions.
  • Check oxygen levels: Low oxygen levels could trigger bubble blowing. Consider installing a water pump or an air stone to improve the oxygen level in your tank.
  • Monitor stress levels: High stress can lead to persistent bubble blowing. Identify and minimize potential stressors, such as inappropriate tank mates, bright lights, or loud noises.

Also Read: Why Are My Neon Tetras Blowing Bubbles?

15. Breathing Fast

Neon tetras may breathe fast due to a lack of oxygen in their tank. However, this is also seen in neon tetras which are under stress due to poor water conditions or aggressive tank mates.

How To Treat

  • Evaluate oxygen availability: Fast breathing can be a sign of oxygen deficiency. Improve the oxygen supply by adding a water pump or an air stone to the tank.
  • Check water conditions: High temperatures or poor water quality can lead to rapid breathing. Maintain the recommended temperature and water quality for neon tetras.
  • Look for signs of disease: Diseases like gill flukes can cause rapid breathing. If suspected, consult a vet for appropriate treatment.

Also Read: Why Are My Neon Tetras Breathing Fast?


If your neon tetra presents any of the signs mentioned above, don’t ignore it.

It usually suggests that your fish is suffering and needs your help.

If you’re unsure about what to do, consult an aquatic veterinarian. An expert is always the best choice for seeking assistance.