I. Basic Size Requirements
Minimum Recommended Size
A single betta fish needs at least a 15cm × 15cm square tank (approximately 3-5 liters of water). A 10cm tank is too small, risking injury from bumping and water quality issues.
For better mobility, many suggest a 20cm × 20cm square tank (about 8 liters).
Ideal Size Range
Tanks measuring 20-30cm in length (e.g., a 20cm square tank or 22×16×17cm rectangle) offer more stable water quality and activity space.
For community betta setups, use a larger container (e.g., a 40×30cm tank can house 15+ bettas to reduce aggression).
II. Key Considerations
Water Quality Stability
Larger water volumes (e.g., 5 gallons/20 liters) make it easier to maintain balanced water parameters.
Behavioral Needs
Bettas swim quickly and need to surface for air, so keep water depth under 20cm and leave anti-jump space at the top.
Filter Selection
For small tanks, use a low-power hang-on-back filter (e.g., 3W Ancai 250), but avoid strong water currents.
III. Special Scenario Tips
Desktop Setups
A 15×15×20cm ultra-clear glass tank balances aesthetics and practicality for desktop use.
Multi-Fish Coexistence
Expand the tank proportionally and add hiding spots (e.g., aquatic plants) to minimize conflicts.
Pro Tip: Avoid round or novelty "block" tanks. Square tanks better support betta health.