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Do Betta Fish Need a Heater? Temperature Requirements

Something that I always had trouble maintaining in the beginning was the right temperature for my betta fish. It made me wonder: do betta fish need a heater?

Quick Answer

Ideally, the temperature for a betta fish should be between 75 and 80 degrees Fahrenheit, or about 23 to 27 degrees Celsius. Therefore, unless you live in a tropical location, you will most likely need a small heater for your betta fish aquarium. There are also other ways to maintain temperatures.

Keep reading to find out everything there is to know about betta fish aquarium water temperature, whether or not you need a heater, and how to maintain the ideal level.

Ideal Temperature for Betta Fish

The ideal temperature for a betta fish is anywhere between 75 degrees Fahrenheit and 80 degrees Fahrenheit, or just over 23 degrees Celsius and just under 27 degrees Celsius.

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With that being said, a betta fish can become accustomed to and survive in waters that are slightly lower or higher, anywhere between 72 degrees Fahrenheit and 82 degrees Fahrenheit. Generally speaking, the perfect water temperature for a betta fish is going to be somewhere around 78 degrees Fahrenheit.

As you’ll see further below, if a betta fish is not housed in the proper water temperatures, there can be some pretty major repercussions.

Do Betta Fish Need a Heater?

As you can probably tell from the temperature requirements that a betta fish has, you will most likely need a heater. 78 degrees Fahrenheit is well above room temperature, and if you live in a location where it gets cold at night, or it’s just cold in general, such as somewhere in the north, you will need a heater.

The simple reality is that betta fish require the water to be at least 72 degrees Fahrenheit, and if it’s not, you’ll start running into some really major issues.

Although having the water be too hot is not as bad as being too cold, this is an issue as well. If the water is either too hot or too cold for your betta fish, it can cause serious health issues, which we’re about to take a look at below.

What Happens If Betta Water is Too Hot or Cold

As mentioned above, there can be some pretty serious consequences if the water for your betta fish is either too hot or too cold. Let’s take a look at what might happen in either case.

Too Hot

  • If the water for your betta fish is far too hot, it can result in an increased metabolic rate. If your betta fish’s metabolic rate is far too high, it will start eating more food and digesting it more quickly too. However, if you start over feeding betta fish because it thinks it needs more food, then it will start running into a variety of digestive issues. Bloating, constipation, and others are all possible here.
  • If the water is way too hot for your betta fish, it also starts to affect its immune system. All of the stress caused by the hot water will start to weaken the immune system of the betta fish, therefore making it far more susceptible to a variety of infectious diseases and other ailments. Living in poorwater conditions makes a betta fish more susceptible to developing disease.
  • At the very least, living in conditions that are far too hot will cause heat stress for your betta fish. Eventually, heat stress can result in death.
  • Something worth noting is that hot water holds on to much less dissolved oxygen and cool water. Therefore, if you notice that your betta fish seems to be having trouble breathing and is always going to the top of the water to breathe oxygen from the air, this might be due to the water being too hot. If the water starts exceeding 82 degrees Fahrenheit from other levels of dissolved oxygen in it will be very low.
  • Living in conditions that are too hot can greatly reduce the overall lifespan of your betta fish.

Too Cold

  • If the water is too cold for your betta fish, it could make them very sluggish and much less active. You might notice that they swim slowly, spend a lot of time near the surface of the water, and just move around a lot less in general. You’ll also notice that they start becoming very lethargic, they’ll probably be less interested in eating, and they will be much less responsive to a variety of stimuli.
  • If the water is too cold, you might also notice that your fish is having digestive issues. This is because fish are ectothermic, and this means that their metabolic rates are influenced by the water temperature surrounding them. If the water is too cold , the fish’s metabolism slows down, which ultimately results in a difficulty digesting food. This can lead to a variety of digestive problems, such as constipation and bloating. At the very least, your betta fish probably won’t want to eat very much.
  • At the very least, cold water can also cause extreme stress for your betta fish. This is known as cold stress, and it generally makes them much more susceptible to a variety of health issues, especially infectious diseases. If you didn’t know, stress in itself can kill fish, so this is something to watch out for.
  • As mentioned above, cold water can lead to stress and a diminished immune system. If the immune system of your betta fish is not functioning properly, it becomes much more susceptible to a variety of fungal pathogens, bacterial pathogens, infections, parasites, diseases, and much more.
  • If the water for your betta fish becomes far too cold, it may start suffering from what is effectively hypothermia, and will quite likely die.

How to Maintain Ideal Water Temperatures for Betta Fish

Now that we know what the ideal temperature range for your betta fish is, and what can happen if the water is either too hot or too cold, let’s go over some tips on how you can easily maintain the ideal water temperature in your betta fish aquarium.

A Heater Helps

The simple reality here is that maintaining the ideal temperature for your betta fish, especially if you live in a cold environment, is nearly impossible if you don’t have a good aquarium heater. 

Therefore, we strongly recommend investing in a good aquarium heater, so your betta fish can be happy and healthy. 

Even better is if you get a heater that has a built-in thermostat, so it will be able to automatically monitor the temperature of the water, and therefore make its own adjustments as needed.

Use Aquarium Thermometers

Although any good aquarium heater worth its money should already come with a built-in thermostat, they aren’t always 100% reliable. Therefore, you may want to get yourself an aquarium thermometer as a backup, so you can separately monitor the temperature of the water without having to rely on the heater.

There are different types of aquarium thermometers out there, including those that have probes that go right inside of the tank, as well as those that measure the temperature through the tank glass. We recommend doing a bit of research into both of them to see which one is ideal for you.

The Location Makes a Difference

The other factor to consider here is location. Finding the right location for your aquarium will help prevent temperature fluctuations from occurring. For instance, you never want to keep your aquarium in direct sunlight.

Not only does direct sunlight cause algae to occur, but it also causes great temperature increases and decreases when it comes and goes. Furthermore, you also don’t want to keep your aquarium in an area that is very windy, as this can have the same effect as the sun. Remember that maintaining a constant temperature is necessary for fish, and constant fluctuations are not ideal in the least.


The bottom line here is that you do need a heater for your betta fish aquarium, and as long as you maintain the proper temperature for your betta fish, it should be just fine.

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