The suitable water temperatures for bettas vary by species. Below are the main classifications and temperature recommendations:
Chinese Betta Species (e.g., Round-tailed Betta, Paradise Fish)
Optimal Water Temperature: 24–28°C, with 25–26°C being ideal. At this range, their metabolism is active, and their colors appear most vibrant.
Temperature Tolerance Range: They can withstand short-term cold spells down to 6°C (Round-tailed Betta) or even 3°C (some varieties). However, prolonged exposure to temperatures below 20°C may cause reduced appetite, dormancy, or illness.
Breeding Temperature: Should be adjusted to 26–28°C to enhance nest-building and hatching success.
Siamese Fighting Fish (e.g., Halfmoon Betta)
Optimal Water Temperature: 22–28°C, with slightly acidic water (pH 6.5–7.2) being preferable.
Sensitivity to Cold: Their activity drops significantly below 20°C, and temperatures below 18°C can be fatal. A thermostat is necessary to maintain stable conditions.
Risks of High Temperatures: Exceeding 30°C may lead to oxygen depletion or "tail burn" disease.
Other Considerations
Temperature Difference Control: When changing water, the temperature difference between new and old water should not exceed 2°C. Daily fluctuations should be kept below 5°C.
Seasonal Management: Heaters are required in winter (especially for Siamese Fighting Fish), and direct sunlight should be avoided in summer to prevent overheating.
Special Varieties: For example, West African bettas (such as Parachela oxygastroides) adapt well to temperatures ranging from 20–28°C.
Summary of Recommendations
Chinese bettas: Highly adaptable to a wide temperature range; a stable environment of 24–28°C is recommended.
Siamese fighting fish: Tropical by nature; strictly maintain temperatures between 22–28°C.
General principle: Temperature stability is more critical than absolute values; avoid extreme fluctuations.