I Recently decided to get a heater to keep the water temperatures higher for my betta. This heater will overheat my tank if I am not watching so I only turn it on during the day.
One night I had left my window open and I woke up to my betta laying on the bottom because the temperature had dropped to 19 degrees Celsius. I quickly turned on the heater and the water temperatures have now been fine however he is still laying on the bottom. I do not see any physical signs of disease or sickness and he will not eat his pelleted food. I am worried that when the temperature dropped he was shocked by it.
He is currently in a 2 gallon tank.