A fish swimming sideways, upside down, or struggling to maintain its position in the water column is likely experiencing swim bladder disorder. The swim bladder is an internal gas-filled organ that controls buoyancy, and when it malfunctions, the fish cannot regulate its depth normally.

The most common cause in aquarium fish is constipation or overfeeding. Dry pellets and flakes expand in the gut and can compress the swim bladder, especially in round-bodied species like fancy goldfish and bettas. Fasting the fish for two to three days and then offering a blanched, deshelled pea can help clear the digestive tract and relieve pressure on the bladder.

Poor water quality contributes to swim bladder issues by causing inflammation and bacterial infections that affect the organ. Test your water and address any ammonia, nitrite, or nitrate problems with water changes.

Bacterial infections of the swim bladder are more serious and may require antibiotic treatment. If fasting and improving water quality do not resolve symptoms within a few days, the fish may need medicated food or a bath treatment. Consult an aquatic veterinarian for proper diagnosis.

Temperature shock can temporarily impair swim bladder function. Ensure your heater maintains a stable temperature appropriate for the species, and avoid rapid changes during water changes.

In fancy goldfish, selective breeding for round body shapes has compressed internal organs, making them genetically predisposed to swim bladder problems. Feeding sinking pellets instead of floating food, soaking dry food before offering it, and including fiber-rich foods like daphnia in their diet helps prevent recurring episodes.

If the fish is eating, active when able, and responds to treatment, the prognosis is usually good. Chronic cases in fancy goldfish may need ongoing dietary management.