Swim bladder disease is the catch-all term for any disorder affecting a fish's buoyancy organ. Symptoms range from floating sideways at the surface to sinking to the substrate to swimming upside-down. The cause is often diet-related (constipation), sometimes bacterial, occasionally genetic.
Fast the fish for 3-5 days. Then feed daphnia or peeled cooked pea (1/4 pea per fish) to clear digestive blockage. If no improvement in 7 days, dose API General Cure (metronidazole + praziquantel) for 5 days. Add aquarium salt at 1 tbsp per 5 gallons - reduces osmotic stress.
Less common in marine fish. When seen, usually bacterial. Move to hospital tank, dose Erythromycin or kanamycin per package directions for 7-10 days. Lower flow + add air stone for oxygen.
Avoid overfeeding. Soak dry pellets 30 seconds before feeding to prevent expansion in the gut. Vary the diet - pellet + frozen + occasional veggie matter. Maintain stable water parameters - swim bladder issues often appear after pH or temperature swings.
Estimated cost: $15-30.
Constipation-induced cases recover within 7-10 days with fasting + pea diet. Bacterial cases respond to antibiotics within 14 days. Genetic cases (especially in fancy goldfish) are usually permanent and require management rather than cure.
Constipation-related swim bladder is not contagious. Bacterial swim bladder (less common) can spread within a tank - quarantine sick fish until you identify the cause.
The single most important disease-prevention step: a 4-6 week quarantine of every new fish before adding to your display. See the complete quarantine protocol.