Is 70 degrees too cold for a betta?
Is 70 degrees too cold for a betta? Lowering Water Temperature for Longevity To extend betta fish longevity by 6 months to a year, I recommend keeping the betta fish temperature range below 75°, but no lower than 70°. Start out at 75° and lower the temperature 1 degree at a time using an adjustable thermostat 20-gallon aquarium heater.