Thank you for your reply. I understand that the size of the tank is, well, almost ludicrous. It was a garage sale item and about 25 years ago I had a few tanks and kept some fish and I figured this was an opportunity to get my daughters (5 and 7) involved. A larger tank is not an option right now, but I can see possibly getting a 10 to 20 gal tank later in the year. Possibly.

I also understand the temp fluctuation issue… or, rather, I understand how it can fluctuate at temperatures HIGHER than the heater would be set for, since if the heater is set for, say, 78F and the ambient air temp is 82, the air temp will drive the water temp to that level relatively quickly. I don't understand, however, how the temp would fluctuate BELOW the temp set by the heater. The heater would come on whenever the temp tried to dip below that level. That's how a thermostat works, is it not?

My main question is about that mini-tank heater being "too hot" for a 1 gallon tank. I don't understand, given that the heater has a thermostat, how this is possible.

I have water in the tank right now, obviously unheated, and the temp varies between 82F during the day to 74F at night. But of course this is summer. In the winter, the air temp in the house is not likely to exceed 68F. So between now and then I need to find a solution for heating this tank unless I end up getting a larger tank at some point.

As for fish, I'd appreciate your recommendations. I'm not particularly fond of goldfish, to put it mildly. 25 years ago I kept dwarf gouramis, opaline gouramis, paradise fish, a betta, angelfish, plecostomus and guppies in a couple of different tanks and I thought it was pretty neat.

Thanks much.