Recommendations for Water Change Frequency for Betta Fish (Siamese Fighting Fish)
Regular Water Changes: Replace 1/3 of the tank water every 3–5 days (use water that has been left to sit and is at the same temperature as the tank water). Avoid full water changes, as they can cause drastic fluctuations in water quality.
Special Circumstances:
If the tank water becomes cloudy, develops an odor, or the fish shows abnormal behavior (e.g., gasping at the water surface, refusing food), immediately replace 1/2 of the water and check the filtration system.
During hot summer months or when feeding the fish more frequently, you can moderately increase the water change frequency.
Important Notes:
When changing water, retain some of the original tank water to maintain the balance of beneficial nitrifying bacteria.
Treat new water to remove chlorine—this can be done by letting the water sit for 24 hours or using a water conditioner.
It is recommended to use a small filter (with low water flow) and regularly clean algae off the tank walls. These steps can effectively extend the interval between water changes. How is your betta fish doing currently? Do you need more specific adjustment advice?