Here’s an analysis of the survival time for betta fish without a filter and relevant recommendations:
I. Short-Term Survival (1–6 Months)
Basic Survival
Experiments show that betta fish can survive normally in an unfiltered tank for 3–6 months, but regular water changes (20%–30% weekly) are necessary. Chinese bettas have survived 20 days without filtration or feeding, while Siamese fighting fish (Betta splendens) require more frequent maintenance.
Key Limitations
Ammonia and nitrogen accumulate rapidly. Nitrifying bacteria start to die after 12 hours, so water quality should be tested every 3 days.
II. Long-Term Survival (Over 6 Months)
Environmental Alternatives
Using aquatic plants (such as water lettuce) and low-density stocking can extend survival beyond six months. Maintain strict temperature control (24–28°C) and avoid algae blooms from intense light.
Risk Warnings
Without filtration, a betta’s lifespan may shorten from 3 years to 1–2 years, and fin rot is more likely to occur.
III. Optimization Recommendations
Water Change Strategies
Small tanks (under 5 liters): Change 1/3 of the water every 3 days.
Large tanks: Change 1/4 of the water weekly.
Emergency Treatment
Add nitrifying bacteria capsules if the water suddenly turns cloudy.
Note: The labyrinth organ allows bettas to tolerate low oxygen, but water quality degradation remains the primary cause of death.