The bubble-blowing behavior of betta fish is mainly related to the following reasons, and different situations may correspond to different physiological or environmental needs:
Breeding Behavior
Nest Building for Courtship: During the mating season (when water temperature is 25–28°C), male bettas blow bubbles to build a bubble nest on the water’s surface. This nest serves to attract females for spawning and protect fertilized eggs. The bubbles are small, dense, and uniform (1–2 mm in diameter), making this a normal breeding behavior.
Behavior Without Females: Even in the absence of females, male bettas may blow bubbles due to their breeding instinct. No intervention is needed, but it’s important to keep their environment quiet.
Water Quality or Health Issues
Oxygen Deprivation or Poor Water Quality: If a betta blows bubbles while also gasping at the surface or breathing rapidly, it may be due to low dissolved oxygen in the water, excessive ammonia levels (>0.2 mg/L), or significant pH fluctuations (>0.5).
Signs of Illness: With gill infections (e.g., fungal or parasitic), bubble-blowing becomes abnormally frequent (over 50 times per hour) or produces unusually large bubbles (>3 mm). These may be accompanied by symptoms like swollen gill covers or white spots on the body.
Environmental Stress
Sudden Temperature Changes: A rapid drop in water temperature (e.g., from 32°C to 24°C) can irritate the gills, triggering abnormal bubble-blowing.
Stress Reactions: Intense light, noisy surroundings, or housing with aggressive fish may cause stress-related bubble-blowing.
How to Respond?
Breeding-Related Bubbles: Leave the bubble nest intact and avoid cleaning it. If breeding is not desired, reduce light exposure and lower the water level to ease the behavior.
Pathological Bubbles: Test water quality (ammonia, pH, oxygen levels), isolate the sick fish, and use medication if necessary.
Environmental Adjustments: Maintain stable water temperatures, increase aquatic plant coverage (>40%), and avoid drastic water changes.