Do Betta Fish Need a Heater?

betta fish

If you have a betta fish, then you know that they can be feisty and fun and colorful. However, when your betta is swimming in waters that are cooler than what they are used to, they might not be able to display their finest traits and brightest pigments.

Although many tanks designed for betta fish, also known as Siamese fighting fish, do not come with heaters, they thrive in warmer temperatures.

This raises the question: Do betta fish need a heater?

The short answer is yes. In order for betta fish to live longer, they need a heater. We’re going to go deeper into this to help you understand why a heater is important. We’ll even give you some tips about choosing the right heater.

Let’s dive in.

Do Betta Fish Need a Heater?

99 percent of the time, betta fish are seen in little cups at the pet store or in bowls. And 99 percent of the time, those fish are unhappy. Part of the reason is because betta fish need heated water.

Here’s why: Unlike us, fish are not warm-blooded. They’re cold-blooded. They cannot generate their own body heat, and they cannot cool themselves either. This means that their temperature is dependent on their surroundings.

For example, when a lizard needs to warm up, it will go sun itself on rocks then move back to the shade when it’s had enough.

For fish, they are at the mercy of the water they live in. Although they can swim to different locations to help regulate their body temperature in the wild, fish in tanks are not as lucky.

This is why you need a heater.

How Important Is a Heater For Betta Fish?

So, you might be thinking, “But I’ve kept betta fish in bowls before, and they were fine! Do betta fish need a heater that much?”

Again, yes.

Betta fish are native to Cambodia, Malaysia, and Thailand, where they live in rice paddies and ponds. These countries are used to long, humid days with intense heat. This means that betta fish are used to living in hot water.

In fact, the typical temperature during breeding season runs around 86 degrees F (30 degrees C). Male bettas will start building bubble nests once the water temperature reaches 80 degrees F (27.7 degrees C).

Even betta fry need warm conditions to hatch and grow into adults. If there is a sudden dip in temperature, they will die.

Now, imagine keeping your betta in a bowl where the water temperature isn’t regulated. Imagine what that is like for them. While rises and falls in temperature are a nuisance to humans, constant fluctuations are fatal to fish.

In conclusion, heaters are very important to betta fish.

What Is The Best Temperature For Bettas?

Best temperature for betta fish is between 76-81 degrees F.
Ideally, you want around 78-80 degrees F for optimal health 80%

76 degrees is still considered a little low. Ideally, you want around 78-80 degrees F for optimal health.

Although 72 degrees is considered outside of the healthy range, betta can tolerate that temperature. Anything below 69 degrees F, however, will stress your fish, weaken their immunity, and may even kill them slowly.

Even the temperature is too low to be fatal, illnesses can occur, such as:

  • Bacterial infections, like fur coat syndrome, which is fatal
  • Dormant ich—white spots on scales—that suddenly appear
  • Fin rot
  • Mouth fungus

If you notice your fish displaying signs of illness, consider checking the temperature of the water.

What Happens When Bettas Get Too Cold?

Bettas are considered tropical fish, meaning they need warm water. They don’t have the same abilities as cold water fish, like common goldfish, to survive in frigid temperatures.

This means that, while a betta can survive slightly cooler water for a short period of time, they don’t have internal regulators to induce hibernation. That is why an excess of cold can kill a betta fish in a matter of minutes or hours.

Here are some signs that your betta is too cold:

  • Slow, lethargic swimming
  • Loss of color and dulled appearance
  • Increased infections and illness
  • Will sit closer to a heater or anywhere the water might be warmer

What Happens When Bettas Get Too Hot?

Now, what happens if your betta is in water that is hotter than average? Well, as with anything else that is too hot for too long, they cook.

If the water is too hot for your betta, you will first notice that they are swimming around frantically. Added heat gives them more energy, yes, but prolonged periods will tax their bodies and over-stress their immune system.

In the event your tank is too hot, you can move it to a ventilated room, place it somewhere in the shade, or have a fan blow across the surface of the water. All these will reduce the temperature.

How Long Will Betta Fish Survive Without a Heater?

Betta living in a heated tank
5 Years 100%
Betta living without a heated tank
1-2 years 25%

Many different factors go into your fish’s survival, but one thing is for certain: water temperature plays a major role in your betta’s health. If you are trying to decide whether to buy a heater or not, then consider the following:

  • What is the ambient temperature of the room where the tank is placed? If it is a constant 78 degrees F, then you probably won’t need a heater.
  • What is the climate where you live? Colder climates mean that temperatures can drop rapidly, affecting the temperature of the water.
  • Do you have the tank near a sunny window? Or a heater?
  • Is there a draft nearby? 

Depending on the answers to these questions, you might be able to go without a heater, especially if you live somewhere without a change of seasons. However, the only way to truly tell if the water for your betta is warm enough is to measure the temperature.

Keep in mind that a single betta living in a heated tank with enough space to swim can live well over 5 years. If that same fish is stuck in a tank without a heater, however, that life expectancy can fall to 1-2 years.

Aquarium Location

One thing a lot of novice aquarists do that isn’t always the safest practice is placing a bowl or tank in front of a sunny window. It is misinformed thinking to assume warm sunlight is going to warm the water.

Most of the time, this isn’t adequate enough, especially in well ventilated rooms. Plus, if the HVAC unit turns on and the tank is directly in the path of that current, it could result in temperature swings, which are just as dangerous as overheated or cold water for your betta.

Aquarium lights alone are also not enough to heat water. Therefore, while location does play a role in the ambient temperature, it is not always safe to rely on that alone. You need to buy a heater.

Tips For Choosing a Great Tank Heater For Betta Fish

So, now that you know that betta fish need a heater, how do you go about choosing one? First, there is a lot of bad, misinformed advice throughout the internet. Because of this, finding a decent tank heater for betta fish is not always simple.

That is why we are going to give you some pointers.

Get a Heater With a Thermostat

What is the point of having a heater if you can’t gauge the water’s temperature? How would you know when the water is heated enough? A thermostat is a particularly nifty feature, particularly for smaller tanks, since those heat much faster than larger ones.

Some thermostats can even be programmed to turn off the heater once the pre-set temperature is reached. This eliminates the chances of killing you fish by overheating them. The good news is that most models these days do come with a thermostat. Just make sure that the heater is a worthwhile investment before buying.

Choose a Fully Submersible Heater

Heaters that can be completely immersed in water will be more efficient than other types. Also, if a heater isn’t designed to be submersed all the way, it can lead to problems that may affect your fish.

Opt For Glass, Not Plastic

Tank heaters are usually tube-like in shape, with the heating elements wrapped in either glass or plastic. However, if you are going to choose one, choose glass. The heat transfer is better, and the glass is easier to clean. Meanwhile, plastic is less efficient at warming water and will get discolored over time.

Other Things To Consider

Here are a few other things to think about when selecting a heater for your betta’s tank:

  • Aim for 3-5 watts per 1 gallon of water. Therefore, if you have a 20 gallon tank, you will need a 60-100 watt heater.
  • The heater should fit in the tank without touching anything—decorations, substrate, or plants.
  • Place the heater in one corner where there is a current. This allows for better circulation.
  • If you don’t have a fully submersible heater, choose a heater that has a screw to attach it to the tank instead of just suction cups. Betta have a tendency to swim between the suction cups, and this can cause the heater to detach from the wall. Most models will have an emergency shut-off switch if this does happen, but you don’t want to test it. 

Emergency Heat Options

What happens when it is wintertime and there is a power failure? What if the heater fails? Aside from losing filtration, your fish also have to worry about rapidly dropping water temperature. Remember, this can be a life or death situation for your betta fish.

In the event there is such an emergency, there are some methods for keeping water within the safe zone. While these emergency heating options are not 100 percent reliable, they will help keep your fish alive for the time being.

betta fish

Hot Water Bottles

For the first method, you will need to remove 1 gallon of water from the aquarium (it will be returned later). Next, grab a few empty plastic bottles or something that will float, and fill them halfway with hot water from the faucet. You don’t want to use boiling water. It should just be hot enough that it will warm the waters of the tank.

Make sure you have a thermometer to check the water once in a while. Change the bottles out once they start to cool.


As long as you have a clean burning candle (one that doesn’t release smoke, soot, or a strong smell), you can place it near the tank to help warm the water. The best candles are either votives or freestanding tapers. Glass-encased candles release far less heat. If it is a heater failure and not a power outage, you can swap candles for a space heater.

Final Thoughts

It is important to think about the wellness of all pets, your fish included. This means that your betta fish also need to be taken care of and comfortable. Aside from having a big enough tank and nutritious food, you need to ensure your betta can enjoy stable water temperatures.

This will help your fish live a longer, healthier life and bring out their both beautiful colors and personality.

Heated water will encourage your betta to swim, play, and eat. It also reduces the risk of diseases. Therefore, if you are not currently using a heat for your betta fish’s tank, then you need to get one as soon as possible.

Interested in learning more about betta fish? Check out our other blogs!

Share on facebook
Share on twitter
Share on pinterest
Share on email
Share on print

Leave a Comment

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