Compiled from multiple reliable sources, the following are the detailed steps and precautions for changing the water in a betta fish tank:
I. Preparation Before Water Change
1. Water Aging Treatment
Tap water must be left to stand for 1–3 days (or treated with a chlorine remover) to allow chlorine to evaporate. This prevents damage to the betta’s gills.
2. Water Temperature Control
The temperature difference between the new water and the old tank water must be ≤ 2°C. Use a thermometer to monitor temperatures and a heater to adjust the new water’s temperature if needed.
3. Tool Preparation
It is recommended to use a siphon tube or gravel vacuum to clean fish waste from the tank bottom. Avoid manually scooping water, as this can easily cause large temperature fluctuations.
II. Water Change Steps
1. Clean the Tank
Use the siphon tube to suck out feces and leftover food from the tank bottom. The amount of water to replace is recommended to be 1/3 to 1/2 of the total tank volume.
For smaller tanks (e.g., cube-shaped nano tanks), you can directly pour out a portion of the old water and gently rinse the tank walls (avoid using soap or chemicals).
2. Slow Water Refilling
Pour the aged (or dechlorinated) new water slowly along the tank wall. This avoids strong water flow from startling or harming the betta.
3. Supplementary Measures
You can add Indian almond leaves (sterilized with boiling water first) or a water conditioner (e.g., products to stabilize water parameters) to adjust and improve water quality.
After refilling, observe the betta’s behavior closely for signs of stress (e.g., erratic swimming, loss of appetite) and address any issues promptly.
III. Water Change Frequency and Water Quality Management
1. Recommended Frequency
For a single betta: Change 1/3 of the water weekly, or replace a small amount of water every 3 days.
During breeding periods or in tanks with high fish density: More frequent water changes are required to maintain clean water.
2. Water Quality Parameters
Maintain a pH level between 6.5–7.2 (slightly acidic to neutral), which is optimal for bettas.
Avoid frequent full-tank water changes, as this can disrupt and collapse the tank’s nitrification system (critical for breaking down harmful ammonia and nitrites).
IV. Common Mistakes to Avoid
Using tap water directly: Failure to remove chlorine can lead to chlorine poisoning in bettas.
Excessive temperature difference: A temperature gap exceeding 2°C may cause fin rot or even death.
Over-changing water: Full-tank water changes easily destroy the tank’s water quality balance and harm the betta’s living environment.
For a more visual guide on specific operations, you can refer to the following video demonstrations: