Angelfish Swimming In Circles: 7 Effective Solutions

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A few months back, I woke up to find one of my angelfish swimming in circles. At first, I thought it was merely playing with its tank mates.

However, when this behavior persisted for a couple of days, I knew something was wrong. That was when I started investigating thoroughly online.

What causes angelfish to swim in circles? Is this a life-threatening case? How do you diagnose the issue and treat it appropriately?

Here, I’ll discuss all these and more. Let’s get started.

Why Is My Angelfish Swimming In Circles?

Angelfish swimming in circles can be a sign of several issues. Here’s an in-depth look at some potential causes:

1. Stress or Anxiety

Angelfish are sensitive to environmental changes, with stress or anxiety often leading to unusual behaviors like swimming in circles.

  • Change in Water Conditions: Shifts in pH, temperature, or ammonia can stress angelfish, causing them to swim erratically as a stress response.
  • Overcrowding or Aggression: Too many fish or aggressive tank mates can lead to stress, reflected in repetitive swimming patterns like circling.
  • Recognition Tip: Look for rapid gill movement and attempts to hide or escape, indicating stress or anxiety in your angelfish.

2. Boredom or Lack of Stimulation

A lack of environmental enrichment can lead to boredom in angelfish, resulting in repetitive swimming behaviors such as circling.

  • Insufficient Environmental Enrichment: A bare or unstimulating tank can cause boredom, leading to repetitive swimming patterns like circling.
  • Limited Space to Explore: A small or clutter-free tank limits exploration, potentially causing boredom and repetitive swimming.
  • Recognition Tip: Observe if the fish swims in circles mainly in an unenriched or small tank, which can indicate boredom.

3. Territorial Behavior

Angelfish are naturally territorial, and circling can be a way of patrolling or defending their territory in the aquarium.

  • Defending Territory: Circling can be a way for angelfish to patrol and defend their chosen area within the aquarium.
  • Presence of New Fish: Introduction of new fish can trigger territorial behavior, resulting in circling as a display of dominance.
  • Recognition Tip: Notice if the circling occurs around specific tank areas or towards certain fish, indicating territorial behavior.

4. Whirling Disease

Whirling Disease is a parasitic infection that can affect angelfish, leading to disoriented swimming patterns like circling.

  • Parasitic Infection: Caused by a parasite, Whirling Disease disrupts the fish’s nervous system, causing erratic swimming.
  • Spinal or Neurological Damage: This disease can cause spinal deformities or neurological issues, leading to circling behavior.
  • Recognition Tip: Look for physical deformities or loss of balance, which are common indicators of Whirling Disease in angelfish.

5. Water Quality Issues

Poor water quality is a major stressor for angelfish, often leading to abnormal behaviors like swimming in circles.

  • Toxic Buildup: Accumulation of nitrites, nitrates, or ammonia in the water can stress angelfish, causing unusual swimming patterns.
  • Poor Filtration or Maintenance: Inadequate filtration or irregular tank maintenance can lead to poor water quality, affecting the angelfish’s behavior.
  • Recognition Tip: Check for cloudy water, foul odor, or visible waste, which are signs of poor water quality in the aquarium.

6. Swim Bladder Disorder

Swim bladder disorder affects the fish’s buoyancy, often resulting in disoriented swimming patterns such as circling.

  • Buoyancy Issues: A malfunctioning swim bladder can cause difficulty in maintaining buoyancy, leading to erratic swimming.
  • Dietary Causes: Overfeeding or improper diet can lead to swim bladder problems, affecting the fish’s swimming behavior.
  • Recognition Tip: Look for difficulties in maintaining a stable position in the water, which is a clear sign of swim bladder disorder.

Also Read: Angelfish Swim Bladder Disorder

7. Overcrowding in the Tank

Overcrowding can cause significant stress and territorial disputes among angelfish, leading to abnormal swimming behaviors.

  • Limited Space: Insufficient space can increase stress and aggression, causing angelfish to swim in circles as a stress response.
  • Competition for Resources: Overcrowding leads to competition for food and territory, resulting in erratic swimming behaviors.
  • Recognition Tip: Observe if the circling behavior coincides with an overly populated tank, indicating stress due to overcrowding.

What to Do If Your Angelfish Swims in Circles

There are a few steps you can take if your angelfish keeps swimming in circles. Consider the following:

1. Managing Stress and Anxiety

Creating a stress-free environment is vital for an angelfish exhibiting circling behavior due to stress or anxiety.

  • Stabilize Water Parameters: Regularly test water quality; maintain pH between 6.8-7.8 and temperature around 76-82°F. Consistent ammonia and nitrite levels at 0 ppm are crucial.
  • Reduce Tank Traffic: Place the aquarium in a quiet area, away from high foot traffic and loud noises, to reduce external stress factors.
  • Provide Hiding Places: Incorporate live plants like Java fern or decorations to create hiding spots, helping your angelfish feel more secure and less stressed.
Lace Java Fern

2. Combating Boredom

Preventing boredom in angelfish requires enriching their environment to stimulate their natural behaviors.

  • Enrich the Environment: Introduce varied decorations, such as driftwood or caves, and rearrange them periodically to keep the environment stimulating. My recommendation: Majoywoo Natural Driftwood (link to Amazon).
  • Introduce New Stimuli: Add items like floating toys or mirror briefly once a week to engage and stimulate the angelfish’s curiosity.
  • Varied Diet: Feed a diverse diet including flakes, frozen foods like brine shrimp, and occasional live foods to keep feeding time engaging and interesting.

3. Dealing with Territorial Behavior

Managing territorial behavior involves ensuring each angelfish has enough space and resources to coexist peacefully.

  • Sufficient Tank Size: Provide a minimum of 10 gallons per angelfish, allowing enough space for each fish to establish its territory.
  • Create Boundaries: Use tank decorations to naturally divide the tank, giving each fish its own area and reducing territorial disputes.
  • Regular Monitoring: Observe fish interactions, especially after introducing new fish, and rearrange the tank if aggressive behavior is noted.

4. Addressing Whirling Disease

Whirling Disease requires prompt attention, focusing on both treatment and preventing its spread.

  • Isolate Affected Fish: Immediately quarantine the affected angelfish to prevent spreading the disease to other tank inhabitants.
  • Consult a Veterinarian: Seek professional advice for appropriate treatments, which may include antibiotics or antiparasitic medications.
  • Improve Water Quality: Regularly change the water and maintain optimal conditions to support the fish’s immune system during treatment.

5. Improving Water Quality

Enhancing water quality is essential for the health of angelfish, especially if poor conditions are causing them to swim in circles.

  • Regular Water Changes: Perform 25-30% water changes weekly to keep the water clean and reduce the buildup of harmful substances.
  • Effective Filtration System: Use a high-quality filter appropriate for your tank size to maintain clean and well-oxygenated water. I personally installed this Fluval C4 Power Filter (link to Amazon).
  • Monitor Water Parameters: Regularly test for ammonia, nitrites, nitrates, pH, and temperature, aiming for ideal angelfish conditions.

6. Treating Swim Bladder Disorder

Addressing swim bladder disorder involves dietary adjustments and creating a stress-free environment for your angelfish.

  • Dietary Changes: Feed high-quality, easily digestible food; consider soaking flakes or pellets to prevent air swallowing and bloat.
  • Peas as a Remedy: Offer cooked, peeled peas which can help alleviate swim bladder issues by clearing digestive blockages.
  • Reduce Stress: Ensure a calm environment and gradually adjust water parameters to reduce stress, aiding in the recovery of the swim bladder function.

Also Read: Angelfish Swimming Sideways

7. Preventing Overcrowding

Managing the number of fish in your tank is crucial to prevent stress and territorial behavior that can lead to circling.

  • Appropriate Stocking Density: Follow the general rule of 1 inch of fish per gallon of water to avoid overcrowding your aquarium.
  • Regularly Assess Tank Size: Upgrade your tank or rehome fish as they grow to ensure adequate space for each individual.
  • Observation and Adjustment: Regularly monitor fish behavior and interactions; if signs of stress or aggression appear, consider reducing the number of fish.

How Fast Will My Angelfish Recover?

The recovery time for your angelfish largely depends on the cause of its distress and the promptness and effectiveness of the intervention.

Issues like stress, anxiety, or environmental factors such as water quality can often see improvement within a few days to a week, provided the conditions are corrected swiftly and maintained.

However, more complex health issues like swim bladder disorder or Whirling Disease may require a longer recovery period, ranging from several weeks to potentially longer, depending on the severity of the condition and the effectiveness of the treatment.

How to Prevent Your Angelfish from Swimming in Circles in the Future

Preventing your angelfish from swimming in circles in the future involves creating a stable, healthy environment and being attentive to their needs.

Here’s what you should do:

  • Regular Health Check-Ups: Schedule periodic check-ups for your angelfish with a vet experienced in fish health to catch and prevent potential health issues early.
  • Controlled Lighting and Sound: Maintain a consistent light cycle (about 12 hours of light and 12 hours of darkness) and keep the tank away from loud noises to minimize stress.
  • Social Compatibility: Carefully select tank mates for your angelfish, avoiding known aggressive species and ensuring compatible temperaments and sizes.
  • Varied Environmental Layout: Change the layout of the tank occasionally, adding new plants or rearranging decorations to provide mental stimulation and prevent boredom.


For quick readers, here’s a short summary:

  • Angelfish swimming in circles can indicate stress, boredom, territorial behavior, Whirling Disease, water quality issues, swim bladder disorder, or overcrowding.
  • Stressful conditions, such as environmental changes or aggressive tank mates, often lead to erratic swimming behaviors in angelfish.
  • Boredom in angelfish, resulting from a lack of environmental enrichment, can cause repetitive swimming patterns like circling.
  • Territorial behavior, often triggered by the presence of new fish, can lead angelfish to swim in circles to patrol or defend their territory.
  • Physical health issues like Whirling Disease or swim bladder disorder can significantly affect an angelfish’s swimming behavior, leading to disorientation and circling.