I understand that the water temperature should be 78-82 degrees and not below 76. I understand that the lid to the tank will hold some heat in the air between the top of the water and the tank lid. It seems that a thermometer in the air space between the water and the tank lid would tell me the temperature of the air that my betta is breathing. What is the lowest air temperature a betta can breath without causing a health concern? I want to make sure I don't cause a problem by turning down the room temperature at night. I am wondering what other owners do about night time room temperatures and what is the safe temperature range of the air my betta is actually breathing.