Hi,

I am turning down the heat this winter to 68 or even 65. I have two bettas. Right now the heat is 68 degrees with evenings at 38 to 45 outside. I have one betta in a ten gallon tank and even with the lower heat his tank stays at 74 to 75 degrees. The larger the body of water the higher the water temp. This tank has no heater. The water will be higher than the room temp. I have a 125 gallon pond in our Florida room, and the pond water was 70 degrees this morning the room was 62 degrees. I have a betta in a 1 1/2 gallon bowl. His bowl has a aquatic themometer in it and it is telling me his water is 62 degrees. He is active and eating making bubble nests like crazy, so far am not concerned he seems to be handling the temperature change just fine. He is real healthy lots of food variety and perfect water conditions. A cycled bowl with 0 ammonia, 0 nitrite, and 5 ppm of nitrate. As you can see, the smaller bowl suffers a real loss of heat. Little water lot of temperature change. I recommend a ten gallon tank to winter bettas. Less heat loss. I have mine alone in a ten gallon tank with pretty decorations and sea scape. He looks just fine all by himself. Flares real pretty at a fake fish I have in the tank.