Is this too hot?

[Alpaca]

I just got a new betta, and along with him I bought a heater since it's been getting colder lately. But with the light on in the tank, the temperature is hovering around 86 degrees! The heater I bought isn't adjustable so I'm a bit worried. I'm unsure if I should take it out, or keep the light off, or just leave it. My thermometer is one of those things you stick on the side of the tank so I'm not even sure if it's accurate.

He seems perfectly fine, probably one of the most active and healthy bettas I've ever seen, but I don't want him to get sick or die or anything....

[Viva]

How many gallons is your tank? I believe I have the same thermometer as you and it works well. Is it this one?

[Alpaca]

Oh, It's a 5 gallon tank, and the heater is 7.5 watts...

The thermometer isn't exactly that one, but it is actually something very very similar!

[Viva]

I've heard a lot of the smaller un-adjustable heaters can fluctuate temps of smaller tanks (like 2 -3 gals) and get them to 8-10 degrees above room temp, but it shouldn't raise it too high in a 5g I wouldn't think. How hot is it in your house, lol? 86 is pretty warm is probably at the threshold of being dangerous.

[paloverde]

How about just turning the light on while you are watching the betta. The light doesn't really need to be on unless you have live plants.