The water volume requirements for keeping betta fish should be determined based on tank size, betta species, and stocking density. Here are specific recommendations:
I. Minimum Water Volume for a Single Betta
Basic standard: Each betta requires at least 5 liters of water; 10+ liters (approximately a 20cm³ cube tank) is recommended.
Species differences:
Sensitive species like halfmoon bettas and crown tail bettas need 500+ milliliters of water.
Chinese bettas can adapt to 3 liters, but 5+ liters is suggested for long-term care.
II. Tank Size and Water Volume Calculation
Ideal specifications:
A 20×20×20cm cube tank (about 8 liters) is suitable for one adult betta.
A 40cm-long tank (30-40 liters) can house 10-15 Chinese bettas (requiring 2-3 liters per fish).
Calculation formula:
Basic method: Length (cm) × Width (cm) × Water depth (cm) ÷ 1000 = Water volume (L).
When accounting for glass thickness, subtract the volume occupied by the tank walls.
III. Water Level and Species Compatibility
General water level: 15-20cm deep, ensuring bettas can easily reach the surface to breathe.
Special species:
Plakat bettas and veiltail bettas can adapt to 30cm water depth (requires surface cover).
Breeding pairs during the spawning period need 20-30cm water depth, paired with a sponge filter for aeration.
IV. Key Water Quality Indicators
pH level: 6.5-7.2 (slightly acidic to neutral).
Ammonia: <0.2ppm; Nitrite: <0.1ppm.
TDS level: 50-150ppm; Dissolved oxygen: ≥3mg/L (at night).
Note: For deep-water setups (>50cm), a thermostat system is required to keep temperature fluctuations ≤3℃.