Neon Tetra Constipation: Causes, Symptoms & Treatments

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Neon tetras that become constipated are the real deal. When this happened to my fish, I immediately panicked.

The fish looked bloated and was unable to swim. Fortunately, after this happened, I gained a lot of experience and knowledge on the topic.

I was also able to save my fish from a cruel fate.

In this article, I will discuss the symptoms, causes, and treatment options you can offer for a neon tetra suffering from constipation. Let’s get into it.

What Causes Constipation In Neon Tetras?

Constipation in neon tetras can be caused by various factors:

1. Inadequate Nutrition

Neon tetras are omnivorous, meaning they eat both plant and animal matter. They need a balanced diet with enough fiber to promote proper digestion.

A diet deficient in fiber or lacking in vital nutrients can potentially cause constipation in neon tetras.

Offering a balanced diet with a mix of high-quality flake food, live foods, and freeze-dried foods can help prevent this issue.

Also Read: 17 Neon Tetra Diseases & Their Treatments

2. Overfeeding

Overfeeding is a common cause of constipation in many fish, including neon tetras.

If neon tetras consume an excessive amount of food, it can overload their digestive system, leading to constipation.

It is recommended to feed neon tetras modest quantities of food once or twice a day, limiting portions to what they can fully consume within a span of one to two minutes.

3. Insufficient Activity

While less common than the previous two causes, a lack of physical activity can also contribute to constipation in neon tetras.

These fish are generally active swimmers and a lack of movement may suggest that they are not well. Regular exercise helps to promote healthy digestion and prevent constipation. 

Keeping them in an adequately sized aquarium with plenty of room to swim, and providing environmental enrichment such as plants and hiding spots can encourage activity.

4. Cold Temperature

Neon tetras are tropical fish that thrive in warm water temperatures between 70 and 81 degrees Fahrenheit (21-27 degrees Celsius).

Lower temperatures can slow down their metabolism and, consequently, their digestion. Continuous exposure to lower temperatures could result in constipation in neon tetras. 

Maintaining a stable, suitable temperature in the aquarium is crucial for their health and well-being.

5. Surface Feeding

Neon tetras are mid to lower-level feeders in an aquarium.

If they regularly feed at the surface, they can ingest air, which can contribute to digestive problems including bloating and constipation.

Try to use slow-sinking food to encourage the fish to feed at their natural level in the tank. 

Furthermore, refrain from giving them substantial food chunks that could be difficult for them to eat, as this could also instigate digestive problems.

What Are The Symptoms Of Constipation In Neon Tetras?

Fortunately, there are symptoms of constipation in neon tetras that can help you identify the problem pretty fast:

1. Enlarged Abdomen

One of the common signs of constipation in neon tetras is an enlarged abdomen.

If you notice that your neon tetra’s belly appears swollen or distended compared to its normal size, it could indicate constipation.

2. Failure to Excrete/Stringy Waste

Constipated neon tetras may have difficulty passing waste or produce stringy feces. Instead of normal feces, you may observe long, white, or clear strands hanging from the fish’s vent.

This can be a result of the accumulation of undigested food in their digestive system.

3. Inactivity/Reduced Swimming

Constipated neon tetras often exhibit signs of inactivity or reduced swimming.

They may spend more time hiding, resting at the bottom of the tank, or displaying sluggish behavior.

If you notice a sudden change in their activity level and they seem less energetic, it could be a sign of constipation.

4. Difficulty Swimming

Constipated neon tetras may experience difficulty in swimming properly. They may struggle to maintain their balance or have an altered swimming pattern.

This can be due to the discomfort caused by the accumulated waste in their digestive tract.

Also Read: Black Spots On Neon Tetras

5. Swim Bladder Disorder

When neon tetras experience constipation, it can lead to the buildup of fecal matter within their digestive system.

The buildup of waste from constipation can place pressure on the swim bladder, impeding its normal functioning.

Consequently, the disturbed swim bladder may cause buoyancy problems, leading to swim bladder disorder symptoms such as difficulty swimming, abnormal floating, or sinking.

Also Read: Neon Tetra Swim Bladder Disease

How To Manage Neon Tetra Constipation

Fortunately, there are several straightforward methods to treat constipation in neon tetras:

1. Fasting Your Neon Tetra

  • Stop feeding your neon tetras for 24 to 48 hours.
  • This allows their digestive system to rest and helps clear any blockages.

2. Offering Peas

  • Thaw frozen peas and remove the outer skin.
  • Cut the peas into small, bite-sized pieces.
  • Feed your neon tetras a small amount of pea once a day for three to four days.
  • Peas act as a natural laxative and can help relieve constipation.

3. Experiment With Epsom Salt

  • Dissolve 1 teaspoon of Epsom salt (link to Amazon) per 5 gallons of aquarium water.
  • Gradually add the dissolved Epsom salt mixture to the aquarium.
  • Monitor the fish closely for any signs of distress or adverse reactions.
  • Epsom salt can help alleviate constipation by promoting bowel movement.

4. Elevate The Water Temperature

  • Increase the water temperature by a few degrees (not exceeding 82°F or 28°C).
  • Warmer water can help stimulate the fish’s metabolism and digestion.
  • Avoid sudden temperature changes to prevent stressing the fish.

5. Replace 25% Of The Water

  • Perform a partial water change by replacing 25% of the aquarium water.
  • Use dechlorinated water that is at the same temperature as the tank.
  • Removing old water and adding fresh water helps maintain water quality.
  • Clean water can promote better overall health, including digestive health.

What Are Other Possible Causes of Swollen Stomach In Neon Tetras?

A distended stomach in neon tetras may also be:

1. Dropsy

Dropsy is a condition characterized by the accumulation of fluid in the fish’s body. It can cause the abdomen to appear swollen or bloated.

Other symptoms may include raised scales, pineconing (scales sticking out), lethargy, loss of appetite, and rapid breathing.

Dropsy is often caused by bacterial infections, organ failure, or poor water conditions. 

Treating dropsy can be challenging, and it’s important to address the underlying cause while providing supportive care.

Consult a veterinarian for appropriate diagnosis and treatment.

2. Egg Binding

Female neon tetras can develop egg binding, a condition where they are unable to release their eggs. This can result in a swollen abdomen.

Signs of egg binding may include a distended belly, inactivity, loss of appetite, and discomfort.

If you suspect egg binding, provide a well-maintained breeding tank with appropriate water parameters, plants, and a spawning site to encourage the release of eggs.

3. Tumors

Tumors, although rare in neon tetras, can cause a swollen stomach. These abnormal growths can be benign or malignant.

Tumors may appear as lumps or masses in various parts of the fish’s body, including the abdomen.

If you notice unusual growths or a persistent swollen stomach, it’s advisable to seek veterinary advice for proper diagnosis and treatment options.

How Can I Prevent Constipation In Neon Tetras?

While it’s possible to treat constipation in neon tetras, prevention is always preferable:

1. Provide A High-Quality Diet

  • Offer a varied diet that includes a mix of live, frozen, and quality dry foods. My recommendation: TetraMin Tropical Flakes (link to Amazon).
  • Avoid overfeeding and provide small portions that the fish can consume within a few minutes.
  • Include fiber-rich foods like daphnia or brine shrimp to promote healthy digestion.

2. Ensure A Spacious Tank

  • Neon tetras require adequate swimming space.
  • Provide a tank with sufficient horizontal swimming room to encourage exercise and natural movement.
  • Avoid overcrowding the tank, as it can lead to stress and poor water quality.

3. Maintain Optimal Water Temperature

  • Neon tetras thrive in tropical temperatures ranging from 75°F to 80°F (24°C to 27°C).
  • Fluctuations in temperature can affect digestion.
  • Use a reliable aquarium heater and monitor water temperature consistently.

Can Constipation Be Fatal For Neon Tetras?

Constipation can be potentially fatal to neon tetras if left untreated or if it leads to severe complications.

The accumulation of waste can cause swim bladder disorder, affecting their buoyancy and balance.

Also, chronic constipation may weaken the immune system, leading to susceptibility to infections and malnutrition.

Prompt attention and appropriate care are essential to prevent a potential fatality.

Can I Feed Neon Tetras Canned Peas?

Neon tetras are primarily insectivores and their digestive system is not well-suited for plant matter like canned peas.

It’s best to provide them with a varied diet of high-quality dry foods, live or frozen small invertebrates, and specially formulated fish flakes or pellets.

If constipation is a concern, other methods may be more effective than feeding canned peas.


Neon tetras with constipation can be relieved by taking the proper measures. The most crucial step is to allow the fish to fast and avoid overfeeding.

Additionally, it is essential to handle meals more appropriately to prevent future occurrences. 

If you are unsure about your fish’s condition or the treatment, I highly recommend consulting an aquatic vet.