Betta fish prefer to live in water that is kept at a temperature range of 78-80°F (25.5-26.5°C) . Although they can tolerate temperatures ranging between 72-86°F (22-30°C), if the water is outside of their ideal range, they may not thrive and can become stressed or susceptible to disease. It is important to maintain a consistent temperature in the tank, as fish tend to be very sensitive to rapid temperature changes, and bettas are no exception. If the water temperature in the tank becomes too high or too low, it is recommended to change the water temperature slowly, which may take several days to reach the desired temperature. A heater is necessary to maintain the ideal temperature range, and it is important to use a thermometer to check the water temperature regularly.