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systemic internal

Swim bladder disorder

Loss of buoyancy control fish floats at the surface, sinks to the bottom, swims sideways, or struggles to maintain position. Can be caused by bacterial infection, constipation/overfeeding, physical injury, genetic defect (common in fancy goldfish), or internal parasites.

Medium prioritypattern match not diagnosis1 source note

Do first

  • Fast the fish for 2–3 days constipation is the most common and easily treated cause.
  • After fasting, offer a small piece of de-shelled, cooked pea (for herbivore/omnivore species) acts as a laxative.
  • Check and correct water temperature. Ensure it is within the species' optimal range.
  • Test water quality correct any ammonia or nitrite.
  • Avoid all floating foods; switch to sinking pellets if the issue recurs after feeding.

Escalate if

  • Swim bladder disorder combined with bloating, raised scales, or lethargy may indicate dropsy.
  • Progressive worsening over days despite fasting.
  • Fish unable to feed due to inability to reach food.
  • Multiple fish in the tank showing buoyancy issues simultaneously investigate water quality.

Water clues

These readings can push this pattern higher or lower in the triage result.

ammonia above zero+2

Ammonia-stressed fish may show swim bladder-like symptoms due to neurological effects test water first.

temp below species min+2

Cold temperatures slow digestion and can cause constipation-related swim bladder issues.

Care protocol

Follow only the steps that fit your species, tank inhabitants, and medication label.

Identifying the cause

  1. Constipation-related: fish floats at top after feeding; often resolves with fasting and pea feeding.
  2. Bacterial infection: fish has other symptoms such as lethargy, color changes, or abdominal swelling beyond buoyancy issues.
  3. Physical trauma: fish was involved in a collision, fell, or was caught/netted roughly.
  4. Congenital/genetic: common in fancy goldfish (ryukin, oranda, telescope eye) may be chronic.
  5. Internal mass or parasites: fish has progressive wasting alongside buoyancy loss.
Cautions
  • Do not treat with antibiotics for swim bladder unless bacterial origin is confirmed or strongly suspected.
  • Persistent swim bladder issues in fancy goldfish may be genetic and untreatable management, not cure, is the goal.

Management protocol

  1. Fast 2–3 days, then offer a de-shelled cooked pea (for omnivores/herbivores only).
  2. Reduce water level in the tank to 8–10 inches if the fish is struggling to reach surface or substrate.
  3. Ensure no aeration or flow is pushing the fish to one side.
  4. If constipation resolves and symptoms remain, consider an Epsom salt bath (1 tsp per gallon for 15–20 minutes) to help with internal pressure.
  5. For suspected bacterial swim bladder infection (often with other systemic signs): treat with a broad-spectrum antibiotic in a hospital tank.
Cautions
  • Never force a fish to swim reduce stress and let it rest near the surface or bottom as it prefers.
  • Epsom salt baths are stressful monitor the fish constantly during the bath.
  • Pea treatment is only appropriate for species that eat plant matter do not use for obligate carnivores.

Source notes

References and context notes used for this triage entry.

Swim Bladder Disorders VCA Animal HospitalsVeterinary consumer reference balanced overview.
Run Symptom CheckerCompare this pattern against water readings, affected count, and recent tank context.Ask AdvisorUse TankFlare Advisor to review this against your saved tank and recent logs.

Related patterns

Similar symptoms or risk factors worth comparing before treatment.

High priorityIntestinal prolapse (rectal prolapse)

A section of intestine protruding from the vent, appearing as a pink, red, or brownish tube-like structure. Often confused with Camallanus worms, but prolapsed tissue is wider, irregular, and does not move independently. Usually caused by severe constipation, straining, internal parasites, or bacterial infection of the gut.

MonitorBloat and constipation (digestive)

Mild-to-moderate abdominal swelling without raised scales, often linked to overfeeding, a diet too low in fiber, or dry food that expands after eating. Very common in bettas, goldfish, and other heavy eaters. Distinguished from dropsy by the absence of pinecone scales and by a more localized, often asymmetric swelling.

UrgentSpring viremia of carp (SVC / Rhabdovirus carpio)

A notifiable viral hemorrhagic disease affecting cyprinids (koi, goldfish, carp) primarily in spring at water temperatures of 11–17°C (52–63°F). Causes hemorrhaging, abdominal swelling, protruding eyes, and mass mortality. SVC is a regulated disease in many countries suspected outbreaks must be reported to animal health authorities.

MonitorOverfeeding and obesity

A fish that is visibly overweight rounded or bulging abdomen that has developed over weeks or months due to consistently feeding too much. Unlike dropsy or bloat from constipation, this is a chronic condition. Common in bettas, goldfish, and cichlids. Fat deposits around organs can cause liver disease, buoyancy problems, and shortened lifespan.