Betta fish dropsy is a highly fatal disease. Below is a breakdown of its symptom progression and key information:
1. Typical Symptom Progression
Early Stage (1–2 Days)
Mild swelling develops just behind and below the gills. However, the betta will still eat and swim normally, though its waste output may decrease.
Initial judgment can be made by monitoring the betta’s defecation: healthy bettas typically defecate within 5 minutes after feeding.
Middle Stage (3–7 Days)
The abdomen becomes noticeably distended, taking on a spherical shape. This is accompanied by behaviors like lying at the bottom of the tank, floating motionless on the water surface, and refusing food.
Complications may arise, such as pineconing (scales standing out from the body) and exophthalmia (bulging eyes).
Late Stage
The betta stops defecating entirely. Its abdominal circumference increases significantly, and it may roll onto its side or sink to the tank bottom. Death often occurs within 48 hours.
Visceral failure leads to an extremely low cure rate, earning dropsy the nickname “fish cancer.”
2. Causes and High-Risk Factors
Water Temperature Fluctuations: Unstable water temperatures during the transition from autumn to winter weaken the betta’s digestive system.
Poor Water Quality: Infrequent water changes or contaminated fish food can trigger bacterial or parasitic infections.
Overfeeding: Continuing to feed bettas normally during cold periods (when their metabolism slows down) often leads to indigestion.
3. Treatment and Prevention Recommendations
Early Intervention
Immediately stop feeding the betta. Raise the water temperature to 28°C (82.4°F) for quiet recovery, and administer a methylene blue bath (20 minutes per day for 4 consecutive days).
Monitor for the return of normal defecation, then gradually resume feeding in small amounts.
Preventive Measures
Maintain a stable water temperature (25–28°C / 77–82.4°F) to avoid sudden changes during seasonal transitions.
Regularly remove uneaten food residues and control feeding amounts—especially reducing portions during cold periods.
Note: Late-stage dropsy (e.g., cases involving organ failure) is usually incurable. If abnormal symptoms are detected, isolate the affected betta immediately.