Swim Bladder Disorder in Fish
A condition affecting buoyancy control. Fish may float uncontrollably, sink to the bottom, or swim at odd angles. Most common in fancy goldfish and bettas. Can be temporary or chronic.
Last updated: 2026-05-06
Severity
mild
When to Act
See Vet Soon
Symptoms & Signs
Floating at the surface
Fish cannot descend and floats at the water surface, often on its side.
Sinking to the bottom
Fish cannot maintain buoyancy and sits on the bottom, struggling to rise.
Swimming at an angle
Fish swims with head up, head down, or tilted to one side.
Distended abdomen
Swollen belly may be visible (constipation or organ enlargement pressing on the swim bladder).
Behavioral Changes to Watch For
Pets can't tell us what's wrong. These behavioral changes are often the first clues that something is wrong.
ðū Struggling to swim normally
Fish expends significant energy trying to maintain position in the water.
What You May Notice:
Your fish is constantly swimming just to stay in one place, or cannot leave the surface.
Causes & Risk Factors
Causes
- âĒConstipation or overfeeding (especially dry food that expands in the stomach)
- âĒBacterial or parasitic infection of the swim bladder
- âĒPhysical trauma or injury
- âĒPoor water quality causing stress and secondary infection
- âĒCongenital deformity (especially in fancy goldfish â their compressed body shape predisposes to swim bladder issues)
- âĒTumor or cyst pressing on the swim bladder
- âĒRapid temperature changes
Risk Factors
- â Fancy goldfish breeds (Oranda, Ranchu, Ryukin â compressed body shape)
- â Bettas in small, unfiltered tanks
- â Overfeeding (especially dry pellets/flakes)
- â Poor water quality
- â Sudden temperature drops
How It's Diagnosed
- 1Observation of buoyancy abnormality
- 2Rule out constipation (fast and observe for improvement)
- 3Water quality testing
- 4Radiographs for goldfish (at a specialized aquatic vet)
- 5Ultrasound if available
Treatment Options
Fasting and Dietary Adjustment
Most cases (especially constipation-related) respond to fasting and diet change.
Steps
- 1.Fast the fish for 2-3 days (do not feed at all)
- 2.After fasting, feed a deshelled, cooked pea (for goldfish) â acts as a natural laxative
- 3.Soak dry pellets in tank water for 5 minutes before feeding to prevent expansion in the stomach
- 4.Switch to sinking pellets instead of floating flakes (reduces air ingestion)
- 5.Feed high-quality, varied diet: gel food, frozen food, vegetables for goldfish
Expected Outcome
Constipation-related swim bladder issues often resolve within 3-5 days.
Precautions
- !Only fast for 2-3 days maximum
- !Not appropriate for very small or young fish
Antibiotic Treatment (if infection suspected)
If fasting doesn't help, a bacterial infection may be the cause.
Steps
- 1.Move fish to a hospital tank
- 2.Broad-spectrum antibiotic (kanamycin or erythromycin in fish formulations)
- 3.Treat for 7-10 days
- 4.Maintain excellent water quality throughout
Expected Outcome
Improvement within 5-7 days if bacterial infection is the cause.
Precautions
- !Antibiotics will not help if the cause is physical (constipation, deformity, tumor)
Physical Support
Helping fish with severe buoyancy problems.
Steps
- 1.Lower water level so the fish can more easily reach the surface for air
- 2.Provide resting spots near the surface (broad-leaf plants, betta hammock)
- 3.Reduce filter current â strong flow exhausts fish struggling to swim
- 4.In severe floating cases, some aquarists use a "sling" or floating container to keep the fish submerged
Expected Outcome
Reduced stress and energy expenditure while underlying cause is addressed.
Precautions
- !These are supportive measures â they don't cure the underlying problem
Common Medications Used
| Medication | Usage | Important Notes |
|---|---|---|
| Kanamycin | Broad-spectrum antibiotic for gram-negative swim bladder infections | Available in fish-specific formulations (Kanaplex). Treat in hospital tank. |
Prevention
- âSoak dry food before feeding
- âFeed a varied diet â not just dry pellets
- âAvoid overfeeding â small amounts 1-2x daily
- âMaintain consistent water temperature
- âRegular water changes
- âFor fancy goldfish: sinking pellets, gel food, and vegetables are best
When to See a Veterinarian
- â ïļFish cannot right itself
- â ïļFloating at surface with skin exposed to air (risk of sores)
- â ïļNo improvement after 5 days of fasting and diet change
- â ïļMultiple fish showing symptoms
Frequently Asked Questions
Can swim bladder disease cure itself?
Prognosis
Good for constipation-related cases. Variable for bacterial causes â dependent on early treatment. Chronic/congenital swim bladder deformity (especially fancy goldfish) may be manageable lifelong with supportive care.
References
- [1] Noga â Fish Disease
- [2] AVMA â Aquatic Medicine
- [3] The Goldfish Council
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