Causes
Constipation: overfeeding, dry pellets that expand in the gut, or low-fiber diet. The expanded gut presses on the swim bladder.
Temperature: cold water slows digestion and worsens swim bladder problems.
Genetic: some lines (double-tails especially) have underdeveloped swim bladders. No cure — manage symptoms.
The Pea Diet
Fast the fish for 2-3 days. Then feed one cooked, deshelled pea (green pea, blanched) — the fiber clears the gut.
Most swim bladder issues resolve within 48 hours of the pea diet. Repeat monthly if the fish is prone.
Chronic Cases
If pea diet fails and fish remains tilted long-term, try daphnia (natural laxative) and epsom salt bath (1 tbsp per 5 gal).
Lower water level to reduce effort to reach the surface. Affected bettas can live normal lives with adjusted care.
Prevention
Soak pellets for 10 minutes before feeding. Feed smaller portions. Fast one day per week.
Maintain temperature at 79-80°F for optimal digestion.