Angelfish Swimming Sideways: 5 Effective Solutions

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I’ll never forget how worried I was when I saw my angelfish swimming sideways in the tank a few years back. I really thought I was going to lose my fish friend.

So, I started looking everywhere online to figure out what to do. But it was tough because I couldn’t find one place that had all the info I needed.

That’s why I decided to write this article. In this piece, I’m going to talk about swim bladder disease, which is usually why angelfish end up swimming on their side.

Why Is My Angelfish Swimming Sideways?

When angelfish swim sideways, it’s often due to a swim bladder disorder.

This condition can be influenced by various factors, including overfeeding or improper diet, bacterial infections, and parasitic infestations.

Here’s what you should know:

Overfeeding or Improper DietLook for a distended abdomen and swimming difficulty.Modify diet: reduce feeding frequency, include fiber-rich foods, control portion sizes, and introduce fasting periods.
Bacterial InfectionsNotice unusual swimming, lethargy, or appetite loss.Use appropriate antibiotics, consult a vet, and ensure clean water conditions.
Parasitic InfestationsWatch for ‘flashing’ behavior, weight loss, or lethargy.Employ anti-parasitic medications, identify the parasite type, and monitor regularly.
Physical TraumaObserve for signs of injury or abnormal swimming.Create a stress-free tank environment with minimal disturbance and adequate hiding spaces.
Rapid Changes in Water ConditionsMonitor for erratic swimming or floating problems after environmental changes.Maintain stable water parameters with regular water testing, consistent temperatures, and frequent water changes.

Also Read: Angelfish Swim Bladder Disorder

1. Overfeeding or Improper Diet

Angelfish are susceptible to swim bladder disorders due to poor dietary practices. Overfeeding and an imbalanced diet are common culprits.

  • Bloating and Pressure: Overeating leads to bloating, exerting pressure on the swim bladder and disrupting its function.
  • Constipation and Imbalance: A diet high in protein but low in fiber can cause constipation, impacting the swim bladder’s buoyancy control.
  • Recognition Tip: Observe for a distended abdomen and difficulty in swimming, which can indicate dietary issues affecting the swim bladder.

2. Bacterial Infections

Bacterial infections can severely impact the swim bladder, resulting in disorders that affect the angelfish’s swimming.

  • Inflammation and Damage: Harmful bacteria can cause inflammation or damage to the swim bladder, leading to buoyancy problems.
  • Systemic Impact: Bacterial infections may not only affect the swim bladder but can also cause systemic health issues in angelfish.
  • Recognition Tip: Unusual swimming patterns, lethargy, and loss of appetite are key indicators of a bacterial infection affecting the swim bladder.

3. Parasitic Infestations

Parasites can infiltrate and damage the swim bladder, causing disorders in angelfish.

  • Physical Damage: Parasites can physically harm the swim bladder, leading to blockages or impairing its function.
  • Secondary Effects: Apart from direct damage, parasites can cause stress and immune responses that further affect the swim bladder’s health.
  • Recognition Tip: Look for ‘flashing’ behavior, where the fish scratches against objects, along with weight loss or lethargy, which can indicate parasitic infestation affecting the swim bladder.

4. Physical Trauma or Injury

Physical trauma or injury can directly affect the swim bladder of angelfish, leading to disorders in their swimming ability.

  • Direct Impact: Injuries near the swim bladder can cause swelling or damage, hindering its function in maintaining buoyancy.
  • Stress Response: Physical trauma often leads to stress, which can negatively impact the swim bladder’s normal operation.
  • Recognition Tip: Observe for signs of injury or abnormal swimming behavior, which might indicate trauma affecting the swim bladder.

5. Rapid Changes in Water Pressure or Temperature

Sudden shifts in water conditions, like pressure or temperature, can cause swim bladder disorders in angelfish.

  • Pressure Fluctuations: Rapid changes in water pressure can disturb the gas balance in the swim bladder, causing buoyancy issues.
  • Temperature Shock: Extreme temperature changes can stress the fish, leading to a malfunctioning swim bladder.
  • Recognition Tip: Monitor for erratic swimming or floating issues following significant changes in tank conditions, which could signal swim bladder distress.

Also Read: Angelfish Swimming Vertically

What to Do If Your Angelfish Swims Sideways

Here are a few steps you can follow if your angelfish suffers from swim bladder disorder and swims sideways as a consequence:

1. Modify Feeding Practices and Diet

Altering the feeding routine and diet is vital for angelfish with swim bladder issues. This approach helps to alleviate digestive strain and restore normal swim bladder function.

  • Reduce Feeding Frequency: Cut down feeding to once every other day, offering only as much food as the fish can consume in about two to three minutes.
  • Incorporate Fiber-Rich Foods: Include boiled, shelled peas in the diet, known for their high fiber content, which aids in easing digestion and preventing constipation.
  • Control Portion Sizes: Serve small portions, roughly the size of the fish’s eye, to prevent overfeeding and reduce digestive stress.
  • Implement Fasting Periods: A short fasting period, lasting 24 to 48 hours, can give the digestive system a break, followed by reintroducing a balanced diet in controlled portions.

2. Administer Appropriate Antibiotics for Infections

Using antibiotics is critical for treating bacterial infections in angelfish. Over-the-counter antibiotics can be effective if used correctly.

  • Veterinary Consultation: Although over-the-counter antibiotics are available, consulting a veterinarian ensures the correct diagnosis and treatment.
  • Use Over-the-Counter Antibiotics: Products like API FIN & BODY CURE (link to Amazon) or Maracyn are available without prescription and can be effective against common bacterial infections.
  • Follow Instructions Carefully: Adhere to the dosage instructions on the product label, typically based on the aquarium’s volume.
  • Maintain Water Quality: Keep the aquarium clean and stable during treatment, as poor water conditions can exacerbate health issues.

3. Treat Parasitic Infestations

Addressing parasitic infections in angelfish is crucial for their health and requires specific treatments.

  • Identify the Parasite: Look for signs of parasites, such as visible spots or abnormal behavior, to choose the appropriate treatment.
  • Choose Over-the-Counter Medication: Select a broad-spectrum anti-parasitic medication available in pet stores, like Prazipro (link to Amazon) or API General Cure (link to Amazon).
  • Apply Treatment as Directed: Follow the treatment instructions precisely, usually involving adding the medication directly to the tank water.
  • Regular Monitoring: Keep a close eye on the fish during treatment and watch for any changes in behavior or appearance to gauge the effectiveness of the treatment.

4. Ensure Stable Water Conditions

Maintaining stable water conditions is crucial for the health of an angelfish with swim bladder issues. Consistent water quality helps reduce stress and prevent further complications.

  • Regular Water Testing: Test the water regularly, aiming for ammonia and nitrite levels at 0 ppm, and nitrates below 20 ppm for optimal health. Use a reliable kit like the API Freshwater Master Test Kit (link to Amazon).
  • Consistent Temperature: Keep the water temperature stable, ideally between 76-80°F (24-27°C), as drastic temperature changes can stress the fish.
  • Frequent Water Changes: Perform partial water changes, about 20-25% weekly, to keep the water clean and reduce the buildup of harmful substances.
  • Proper Filtration: Ensure the tank has an efficient filtration system to maintain clear and healthy water, reducing the risk of swim bladder problems.

5. Provide a Calm and Stress-Free Tank Environment

Creating a stress-free environment in the tank is essential for the recovery of an angelfish with swim bladder disorder. A serene setting promotes healing and overall well-being.

  • Minimize Noise and Disturbance: Keep the tank in a quiet area away from loud noises and frequent disturbances to minimize stress for the fish.
  • Adequate Hiding Spaces: Arrange the tank with plants and decorations to provide hiding places, offering a sense of security for the angelfish.
  • Gentle Lighting: Use soft, non-glaring lighting in the aquarium to create a calming atmosphere and reduce stress for the fish.
  • Limit Handling: Avoid unnecessary handling or netting of the fish, as this can cause additional stress and exacerbate swim bladder issues.

Will My Angelfish Heal from Swim Bladder Disorder?

The prognosis for angelfish recovering from swim bladder disorder varies depending on the cause and the timeliness of treatment.

In cases where the disorder is caused by dietary issues or environmental factors, and if addressed promptly, the recovery rate can be quite high, with up to 70-80% of fish showing improvement within a few days to a week.

However, in more severe cases, such as those resulting from chronic infections or physical trauma, the recovery chances might be lower, with successful treatment rates dropping to around 30-50%.

How Can I Prevent Swim Bladder Disorder in the Future?

Preventing swim bladder disorder in angelfish involves careful attention to their diet, environment, and overall health.

Establishing and maintaining the right conditions in your aquarium can significantly reduce the risk of this disorder.

  • Balanced Diet: Feed your angelfish a varied diet that includes both high-quality dry food and fresh or frozen foods like bloodworms, to ensure nutritional balance.
  • Controlled Feeding: Limit feeding to twice a day, giving only as much as the fish can eat in two to three minutes to prevent overeating and digestive issues.
  • Regular Water Checks: Perform weekly water tests, aiming to keep ammonia and nitrite levels at 0 ppm, and nitrates below 20 ppm for optimal health.
  • Stable Environment: Maintain a consistent water temperature between 76-80°F (24-27°C) and provide a calm environment with minimal stress factors.

Less Common Reasons for an Angelfish Swimming on Its Side

Angelfish swimming on their side can sometimes be due to less common reasons like congenital abnormalities, neurological disorders, or exposure to toxins.

Consider the following:

1. Congenital Abnormalities

Some angelfish may have congenital issues affecting their swim bladder or body structure, leading to unusual swimming patterns.

  • Structural Issues: These abnormalities are often related to genetic factors and can include irregular swim bladder development or body deformities.
  • Recognition: Look for signs from a young age, such as persistent abnormal swimming or body shape differences compared to other fish.
  • Treatment: While there’s no cure for congenital abnormalities, providing a stress-free environment and careful handling can improve quality of life.

2. Neurological Disorders

Neurological issues in angelfish can result in loss of balance or coordination, affecting their swimming ability.

  • Brain Function Impact: These disorders can be due to genetic factors, injury, or disease, affecting the fish’s brain and nervous system.
  • Recognition: Symptoms include erratic swimming, difficulty in maintaining upright position, or unusual reactions to stimuli.
  • Treatment: Treatment varies based on the cause but may include maintaining optimal water conditions and minimizing stressors in the environment.

Also Read: Angelfish Swimming In Circles

3. Exposure to Toxins or Chemical Imbalances in Water

Chemical imbalances or toxins in the aquarium can adversely affect the health of angelfish, including their swimming behavior.

  • Water Quality Issues: Harmful chemicals, such as high levels of ammonia, nitrites, or heavy metals, can disrupt normal swim bladder function.
  • Recognition: Signs include sudden onset of sideways swimming, gasping at the surface, or other fish showing similar symptoms.
  • Treatment: Immediate water testing and correction of any imbalances or removal of toxins, followed by partial water changes, are essential steps.


For quick readers, here’s a short summary:

  • Angelfish swimming sideways is often due to swim bladder disorder, commonly triggered by dietary issues, infections, or environmental factors.
  • Overfeeding and poor diet contribute significantly to swim bladder problems in angelfish, leading to bloating and constipation.
  • Bacterial infections and parasitic infestations can cause inflammation or damage to the swim bladder, leading to swimming difficulties.
  • Physical trauma and rapid changes in water pressure or temperature can adversely affect the swim bladder, impacting the fish’s buoyancy.
  • Preventative measures for swim bladder disorder include a balanced diet, stable water conditions, and minimizing stress in the tank environment.