Hey everyone, I've had this 10 gallon since Christmas and the temp outside was dropping past -30*c and when this happened, the tank thermometer was fluctuating. Even now half way through summer it still fluctuates quite a bit when I have the light on or off. I read a bit through Google, but would like to hear some opinions. I currently have a female Betta in the tank which may be moved to a different tank,as it doesn't get along with guppies. Then I was thinking of putting in 4-5 guppies. Thoughts?