physical or bacterial · freshwater tank

Swim Bladder Disease

Swim bladder disease is a malfunction of the air-filled organ that controls fish buoyancy. Affected fish float at the top, sink to the bottom, or swim sideways/upside down.

Reviewed by Fast Aquatics husbandry team · Updated May 2026
Severity: Moderate - usually treatable except in genetic-deformity goldfish

Symptoms

What causes it

Constipation (most common), bacterial infection, physical injury, water temperature shock, or genetic deformity (common in fancy goldfish).

Treatment options

Always treat in a separate quarantine tank.

Fasting + peas. Skip feeding for 2-3 days. Then offer skinned cooked peas (deshelled). Resolves 70%+ of cases (constipation-related).
Water temperature increase. Raise to 78-82°F slowly for 5-7 days. Speeds metabolism + healing.
Kanamycin (bacterial cases). If fasting + peas don't work in 5-7 days, suspect bacterial. Treat in hospital tank.

Prevention

Pre-soak dry pellets to prevent expansion in the gut. Feed varied diet. Don't overfeed.

Frequently asked questions

What does Swim Bladder Disease look like?

Floating sideways or upside down. Sinking and unable to swim up. Difficulty maintaining position.

What causes Swim Bladder Disease?

Constipation (most common), bacterial infection, physical injury, water temperature shock, or genetic deformity (common in fancy goldfish).

How is Swim Bladder Disease treated?

Fasting + peas: Skip feeding for 2-3 days. Then offer skinned cooked peas (deshelled). Resolves 70%+ of cases (constipation-related).

Can Swim Bladder Disease be prevented?

Pre-soak dry pellets to prevent expansion in the gut. Feed varied diet. Don't overfeed.

How fatal is Swim Bladder Disease?

Moderate - usually treatable except in genetic-deformity goldfish

Related

Browse the full disease database for 45 aquarium conditions with treatment protocols, or check the care library for prevention-focused husbandry guides. Use our symptom matcher to rank likely diseases from observed signs, the water parameter checker to diagnose related water-quality issues, or the QT timeline calculator to plan a treatment schedule.