It’s 5:00 in the morning, and you are awakened by a small sudden cold snap, be it your home’s heater has broken, your room mate won’t allow it to be on, or in my case, it’s a gas heater that’s been “summerized” and your family won’t get it ready for winter until later on in the fall months.

By instinct, you decide to check on your Betta and come to find out, your thermometer is reading in the mid 60’s and your Betta is thrashing around, freezing almost to death. And since it’s a 1 gallon tank, you can’t heat it with an aquarium heater without boiling your Betta.



You are now in a state of code red panic. What can you do? First, the best thing to do is, if you have a fan running, either turn it off completely, or turn it to its lowest setting. Also, if your air conditioner is on (because someone left it on) Turn that off as well. (Here in AZ, I have a swamp cooler, and it’s not uncommon that it’s left on during the night, as it gets hot in the day time.)

Now, heating your Betta’s 1 gallon tank. There are several ways you can do this, but the one I am most familiar with is the “hot water” method, as in hot water bottles or a soda bottle. The one I use most is the Hot Water Bottle Method, as it’s easier to maneuver than a soda bottle, even as a soda bottle stands up better.

Be prepared, as this may take anywhere from 1 to 3 hours. You must be patient during this time, as your Betta is in enough stress as it is.

For the Hot Water Bottle Method:

Note: Hot Water Bottles can be purchased at Amazon or drug stores for about $10.

Once you’ve turned the air conditioner and the room fan (if you have one) off, you will need to fill your hot water as hot as your tap water will allow (never use boiling water; the rubber will melt). This can get anywhere from 105 to 120 degrees F.

The best bet would be to get it around 105 to 110 degrees F. You’re probably thinking the temperature is too high. Yes, but we’re not finished. You will need some insulation now. You need to wrap your Hot water bottle in paper towels, enough to form 1 to 2 layers, depending on the thickness of the paper towels (since water bottles have their own insulation through the rubber naturally, 1 layer should actually be enough if you have thick towels).

Once this is done, place the hot water bottle on one of your tank’s walls. In a moment or two, you should see Your Betta swim toward the bottle and hover there. This is okay. He needs the warmth.

For the Soda Bottle Method:

Follow the same steps as above but, I would drop the hot water temp to about 105 degrees F max to keep the plastic from melting or warping.

Again, use a layer of insulation to keep the tank from becoming too hot, and place the bottle by the tank.

To circulate the heat:

Also, if you have an underwater filtration set up, make sure it’s working too. You will need the water circulating to get the temperature even. If you don’t, you might want to re-locate your Hot Water Bottle or soda bottle to another area of the tank once every 10 minutes to avoid a particular area from getting too hot for your Betta to handle.

What Is Happening:
By placing a water bottle about 30 to 35 degrees hotter than the “normal” temperature range with insulation by your tank, you are essentially creating a miniature heater system.

With circulation of the water, either by using your undergravel filtration or rotating the area of your bottle every 10 min. or so, you are warming your water slowly but evenly. As you watch your thermometer, you will notice it slowly rising a degree or two every 15 min. or so.

Yes, it’s slow, but your Betta’s life depends on you at this point in time and will also be seen more often than not around the hot water bottle keeping warm. Don’t give up.

Note: You can try to make the temperature go up faster by removing the insulation and placing it directly on the tank, but I only recommend that for the Hot Water Bottle, not the soda bottle. Hot water bottles tend to be generally thicker and in a sense, have their own “insulation”. However, if you decide to do this, exercise extreme caution and rotate the bottle more often, about every 7 minutes or so, as you will be putting more heat into the tank than you would if you had insulation.

Why so hot?

When you place a hot water bottle (or soda bottle) by the tank, it is also radiating heat to your room as well as the tank. On top of that, the heat must travel through the insulation and the wall of the tank to warm the water. All things considered, the temperature entering a tank is actually lower than what you started with.

By being a bit hotter, you are making sure that the tank is getting the heat it needs while compensating for the other elements around you.

Checking Your Progress:
*Check the temperature of the Hot Water Bottle or soda bottle every 30 minutes. If it starts to feel cool to the touch, dump the water out in your sink and refill it. *Continue to watch your Thermometer while you are using your bottle. Once it gets to at least 75 degrees F, you are out of danger.

As mentioned before, this will take a while. Patience is a must.

Note for those with an external (Liquid Crystal) thermometer:
A liquid crystal thermometer is very sensitive to external heat as well as the heat in the tank. It is highly recommended to avoid that particular spot while warming the tank to maintain an accurate temperature; however, if you use the hot water bottle in the area where the liquid crystal thermometer is, you will need to allow 5-10 minutes of “cooling time” -after you move the bottle to another area- so that the external thermometer can adjust to the proper tank temperature. Then, continue checking the temp as normal.

How To Prevent “Cold Snaps” in a 1 Gallon Tank:

There are several things you can do to prevent the water in your Betta’s tank from getting cold.

  1. First and Foremost, make sure you can keep a temperature of at least 75 degrees in your house. If you need to, turn off the Air Conditioner, Swamp Cooler, fans, what have you, to keep the temperature from falling at night.
  2. If you can’t keep the temperature regulated above 75 degrees, then there are several things you can use to heat your tank without the aquarium heaters:
    • Hot Water Bottles or Soda Bottles with insulation (as described above, but lower the temperature a little, to about 100 degrees F, or you may add an extra layer of insulation instead of lowering the temperature. This allows you to maintain, rather than raise, the temperature.)
    • Seedling Heater Mats
    • Heating pads w/waterproof coating and variable temperature settings. Note: The Hot Water Bottle tends to lose heat rather quickly. The Soda bottle, even though it’s two leaders, needs to be properly insulated or it will lose temperature rapidly as well. You can try wrapping the Soda bottle in aluminum foil to retain its temp (The hot water bottle, being rubber, already acts like a soda bottle with aluminum foil, thus adding foil will defeat its purpose by insulating it too much), but I would recommend the Seedling Heater mats and the Heater Pads, using the Hot Water Bottle or Soda Bottle as a last resort.
  3. If you can, always keep an eye on your Thermometer.

Why Can’t I use an Aquarium Heater?Marina Submersible Heater for Aquarium

Aquarium Heaters are designed for 5 gallon tanks and up, and it’s recommended you have 5 watts for every gallon. Since the lowest wattage that manufacturers make is 25 watts, you won’t find any heaters suitable for a 1 gallon tank.

If you do use a heater, even a 25 watt one, it is often uncontrollable and you have a very high risk of getting the temperature too high too fast, resulting in not only stress, but you could easily kill your Betta from too much heat.

I hope this will help you in heating your Betta’s 1 gallon tank properly without any nasty side effects.

happy betta fish

Post Rating
1 Star2 Stars3 Stars4 Stars5 Stars (1 votes, average: 5.00 out of 5)
Loading...

Reader Interactions

Leave a Reply

Your email address will not be published. Required fields are marked *