Here’s a comprehensive analysis of whether betta fish need a filter:
I. Core Functions of a Filter
Water Quality Maintenance
Filters continuously remove waste and leftover food, reducing the buildup of ammonia and nitrites. This lowers the frequency of water changes—ideally 1-2 times per week.
Support for the Nitrification System
Nitrifying bacteria in biological filter media break down organic matter. Filters must run 24/7 to keep these bacteria active.
II. Betta-Specific Solutions
Recommended Low-Flow Devices
Sponge filters: Use air bubbles to circulate water, allowing control over flow strength and easy coverage with a lid.
Buffered cotton waterfall filters: Pair with pre-filter cotton to slow water flow.
Alternatives for Still-Water Keeping
If no filter is used, the following must be done:
Test water parameters daily.
Replace 1/3 of the water weekly and add nitrifying bacteria.
Introduce freshwater snails or other biological cleaners.
III. Usage Tips
Long-Term Keeping
Opt for a sponge filter or mini external canister filter, running it 24/7.
Short-Term Emergencies
In small tanks (under 15 liters), replace 1/3 of the water daily and use almond leaves to regulate water quality.
Important Notes
Avoid direct strong light.
Adjust water flow so it doesn’t disturb the betta’s fins.
Choosing a filter depends on balancing water stability with the betta’s preference for still water, based on your specific keeping needs.