Swim Bladder Disorder in Aquarium Fish: Causes, Symptoms, and Treatment

 

If you've noticed one of your fish swimming erratically, floating upside down, or sinking to the bottom of the tank, it could be a sign of swim bladder disorder. While alarming to witness, swim bladder issues are common and often treatable, especially with early intervention.

In this guide, we’ll explain what swim bladder disorder is, what causes it, how to spot the signs, and how to effectively treat and prevent it in your aquarium.

 

What Is Swim Bladder Disorder?

The swim bladder is an internal gas-filled organ that helps fish control their buoyancy. It allows them to maintain their position in the water column without constantly swimming. A healthy swim bladder inflates and deflates to regulate the fish’s ability to float or sink.

Swim bladder disorder occurs when this organ is compromised, causing balance and buoyancy issues.

 

What Does Swim Bladder Disorder Look Like?

Swim bladder issues often appear as a fish’s inability to control its buoyancy. You might see them struggling to swim properly, floating upside down, or sinking to the bottom of the aquarium. While it may look unusual, it’s also a clear sign that something is wrong and should be addressed promptly.

 

Signs of Swim Bladder Disorder

Symptoms can vary by species, but here are the most common signs that a fish may be suffering from swim bladder issues:

• Floating upside down or on its side

• Sinking to the bottom and struggling to rise

• Staying vertical with the head pointing down or up

• Difficulty swimming or maintaining position in the water.

• Distended belly or bloating

• Lethargy or lack of appetite

These symptoms are often more noticeable in species with rounder bodies or long fins. The affected fish may also show a swollen or distended abdomen. Unfortunately, other tank mates may start to bully the fish, seeing it as weak or vulnerable.

It’s important to identify the underlying cause and begin treatment as soon as possible to prevent the condition from worsening.

 

What Causes Swim Bladder Disorder?

Swim bladder problems can stem from a variety of factors:

• Overfeeding or constipation – One of the most common causes; uneaten food or excessive intake can compress the swim bladder.

• Excessive air intake – Fish that gulp air at the water’s surface, especially while feeding, can accidentally swallow air, leading to overinflation of the swim bladder. This added air pressure can disrupt their buoyancy and swimming behaviour.

• Poor water quality – High levels of ammonia, nitrites, or low oxygen levels can cause inflammation or stress.

• Bacterial infections – Internal infections can cause inflammation or damage to the swim bladder.

• Physical injury – A fish injured during transport or by tank mates can suffer swim bladder trauma.

• Birth defects – Some fish are born with malformed swim bladders. While this may affect their appearance or swimming style, as long as their quality of life isn’t significantly impacted, many can still live long, healthy lives.

 

Fish Species More Prone to Swim Bladder Issues

Whilst any type fish may develop a swim bladder issue certain species are more susceptible due to their body shape or genetic traits:

• Fancy goldfish (like Orandas, Ryukins, and Fantails)

• Betta fish

• Mollies and guppies

• Angelfish

• Balloon mollies and platies

Fish with compact body shapes often have limited space for internal organs, making them more prone to swim bladder issues. If you keep these species in your aquarium, taking preventative steps can help reduce the risk of problems developing.

 

Prevention Starts with Good Habits

Ensuring your aquarium has clean, stable water and keeping stress levels low are fundamental to preventing disease and supporting the overall health and vitality of your fish. Stress weakens the immune system, making fish more susceptible to illness, while unstable or poor water quality can create an environment where harmful bacteria and parasites thrive.

You can create a balanced ecosystem that encourages healthy, vibrant aquatic life by consistently practicing these simple yet effective habits:

Feeding A Suitable Diet

Opt for high-quality sinking or slow-sinking pellets instead of flake foods to help reduce air intake during feeding. Flakes can expand in the fish’s stomach after being eaten, which may lead to unintentional overeating and digestive issues.

A pellet-based diet offers better control over portion sizes and is typically more nutritionally dense than flake food, ensuring your fish receive the essential nutrients they need to stay healthy.

 

Avoiding Overfeeding

Avoid overfeeding by sticking to small, measured portions. While it’s tempting to feed often, excess food can lead to stomach overexpansion, which may put pressure on the swim bladder and cause buoyancy issues.

Feeding just once a day helps minimize the amount of food in the digestive tract at any given time, making digestion easier and reducing the risk of related health problems.

 

Regular Water Testing

Use a reliable test kit to keep track of water parameters and ensure they remain stable. Poor water quality places unnecessary stress on fish and significantly increases their vulnerability to illness and other health problems.

For more detailed information on water quality and how to maintain optimal conditions, explore our guide, "Understanding Your Aquarium Water." It offers an in-depth look at what’s really happening in your tank and how to keep your water parameters in check.

 

Adjust Filter Flow for Fish Comfort

Make sure your filter’s output isn’t too strong, particularly for delicate or slow-swimming fish. Constantly swimming against a strong current can drain their energy, leading to stress and even exhaustion. A gentler, slower flow allows fish to swim comfortably, rest, and relax.

 

Maintain a Consistent Cleaning Routine

Carry out small, weekly water changes and regular tank maintenance to minimize stress and promote overall fish health. Frequent, smaller water changes are far less stressful for fish than occasional large ones, helping to avoid sudden temperature shifts and fluctuations in water parameters.

This steady approach creates a more stable environment, reducing the risk of stress-related issues, including swim bladder problems, thus supporting long-term fish well-being.

 

How to Treat Swim Bladder

Even with the best care and a well-maintained tank, some fish may still develop swim bladder issues, especially those prone due to their body shape or genetics. The key is not to panic. What matters most is acting quickly and calmly to give your fish the best chance of recovery.

We’ve developed a reliable, step-by-step treatment method based on experience and proven results. By following our guidance, you’ll be able to support your fish through this condition and greatly increase the likelihood of a full recovery.

 

Recommended Products to Treat Swim Bladder Disorder

Here are some trusted products we supply, that can help to aid in the recovery process of Swim Bladder issues:

• API Melafix – Natural antibacterial remedy for mild infections.

• eSHa 2000- Treats a wide range of bacterial issues, including early symptoms of dropsy.

• NT Labs Anti Internal Bacteria Treatment – Combats various internal bacteria that may be responsible for a range of symptoms in the fish.

• NT Labs Swimbladder Treatment - Specifially designed to target bacterias that can lead to Swim Bladder Disorder. Aids the fish in recovery from buoyancy and stability issues.

Important Note:

When treating your aquarium, keep in mind that not all medications are compatible. Some may cause adverse reactions when used together. Always read the instructions carefully and follow the manufacturer’s guidelines to ensure safe and effective treatment.

 

Step – By- Step Treatment Plan

Check out our step-by-step guide to help fish struggling with swim bladder issues. This reliable method has been proven to effectively treat swim bladder problems in your tank.

Follow each step closely to ensure the best outcome for your fish’s health and recovery.

1. Fasting

Begin by fasting your fish for 2–3 Days. Healthy fish can easily go without food for a few days. If the swim bladder issue is due to overfeeding or constipation, a short fasting period allows the digestive system to reset and helps relieve pressure on the swim bladder caused by a full or bloated stomach.

 

2. Improve Water Quality

Perform a partial water change (10–25%) and test water parameters. Keep ammonia and nitrite at 0 ppm and nitrates below 20 ppm. Ensure pH and KH are suitable for the species under treatment.

 

3. Reduced Water Flow and Increased Oxygenation

Reducing water flow helps fish with swim bladder issues by making it easier for them to stay balanced and swim. At the same time, increasing oxygen levels supports recovery by reducing stress and boosting overall health. Together, these adjustments create a calmer, more supportive environment for healing.

 

4. Increase Fibre

After the fasting period, offer your fish a boiled, deshelled green pea. For smaller fish, offer a reduced portion, typically, a quarter of a pea is enough.

Peas are rich in fibre and can help relieve constipation, a common cause of swim bladder issues. The added fibre helps clear any remaining food from the digestive tract.

 

5. Tonic Salt Bath

Tonic salt helps reduce swelling and ease constipation; it can be administered as an intensive bath treatment.

Salt Bath Treatment:

Dissolve aquarium salt in a small container filled with tank water (e.g., a 1L jug), using a dose of 25g per litre. Gently place the affected fish into the solution for up to 3 minutes, closely monitoring them throughout. After the bath, return the fish to the main aquarium.

 

6. Medications

If you suspect a bacterial infection, use an antibacterial treatment specifically designed for internal infections.

Choose one of the recommended treatments, previously mentioned, and begin the course as directed.

Be sure to follow the instructions provided on the packaging carefully. Depending on the medication, multiple courses may be required to achieve noticeable results. Repeat the treatment, as necessary.

7. Post-Treatment Recovery Tonic

After completing the medication course, add NT Labs Aquarium Tonic Salt to support your fish during recovery. This gentle tonic helps reduce swelling and stress while providing a general boost to overall health. It's safe and beneficial for all fish in the aquarium.

Full Tank Dosage:
To treat the entire aquarium, add tonic salt directly at a rate of up to 3g per litre. Pre-dissolving is not necessary—simply spread the salt evenly across the water surface and allow it to dissolve naturally.

 

8. Continue Monitoring and Gradually Reintroduce Food

Keep a close eye on your fish for the next one to two weeks, maintaining a minimal diet during this period. If no further symptoms appear, you can gradually increase their food intake or begin reintroducing treat foods into their diet, if you wish.

By the end of this treatment plan, your fish should be recovering well and showing signs of normal, healthy behaviour.

 

The Importance of Aeration During Treatment

When using medications to treat your aquarium, oxygen levels may drop. Elevated temperatures in tropical tanks can reduce dissolved oxygen, and certain treatments can add stress or negatively affect water quality.

Enhancing aeration ensures your fish get enough oxygen, helps maintain stable water parameters, and supports their immune system during recovery. Adding an air pump or increasing surface movement can greatly improve treatment outcomes and overall fish health.

 

Swim Bladder vs. Dropsy: What’s the Difference?

Although swim bladder disorder and dropsy may appear similar, they are distinct conditions that require different treatments. Many fish keepers mistake one for the other, but it’s important to know the difference.

Early diagnosis and treatment are key to improving the chances of recovery for both conditions. If left untreated, swim bladder issues can sometimes develop into dropsy, a far more serious and often fatal condition.

See the comparison below to help you identify which issue your fish may be facing and determine the best course of action.

 

If your fish is bloated with raised, pinecone-like scales, it’s likely suffering from dropsy—a more severe and difficult condition to treat. If you’re unsure whether your fish has swim bladder disorder or dropsy, feel free to contact us. We’re happy to help identify the issue and recommend the best treatment approach.

 

Take Action Early – Support Your Fish’s Recovery

Swim bladder disorder can be concerning, but with prompt care, most fish recover fully. Keep a close eye on their behaviour, maintain excellent water quality, and provide a well-balanced diet to help prevent future episodes.

Noticed signs of swim bladder issues? Don’t wait. Check your water parameters, fast your fish for a few days, and begin treatment right away to give them the best chance of recovery.

Need help identifying symptoms or choosing the right treatment? Visit us in-store or get in touch—our team is always here to support you.

Looking for more aquarium care advice? [Click Here] to explore our other blog articles for tips, guides, and expert insights to keep your fish happy and healthy.

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