It costs a lot to have fish tanks, When I had Fifteen tanks running my power bill was almost 4 times what it is now with none.The house has a gas heater I don't use it though the house has been remodeled very recently so is insolated well I just got my power bill and it skyrocketed and the fish room is the only thing I could think of because of the weather and I was thinking it might be cheaper to heat the room instead