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Your Easy Guide to Betta Fish Water Temperature

Betta fish are some of the hardiest and most adaptable aquarium fish in the world. This makes them super popular with new fish keepers because they will shrug off changes that can harm or kill less hardy fish species.

betta fish water temperature

However, there is something that not many fish keepers realize. Betta water temperature is very important to keep track of. And while they are very flexible, if you keep the water too warm or too cool for a long time you run the risk of your betta becoming very sick.

So what is the right betta fish water temperature? Let’s take a closer look at this topic together!

Choosing the Right Betta Fish Water Temperature 

Bettas are tropical fish by nature. In the wild, they are found exclusively in Southeast Asia, in countries like Thailand, Myanmar, and Vietnam.

All of these places are very close to the equator, which means that the seasons don’t vary as much as they do in countries that are further north.

Cold spells can still pass through these counties but they are both rare and minor compared to places like the United States in winter. The average water temperature in the lowland, warm regions that betta prefer is anywhere between 70-85℉. Meanwhile, the average room temperature in many places up north is around 65-68℉. 

This betta fish temperature range is not fatal to them, because they are hardy and adaptable

. In the wild they are found in shallow ponds, pools, and streams where sudden shifts in temperature happen all the time. But prolonged cold periods are not natural for them, nor are they healthy in the long term.

Why Pet Store Temperatures are Bad for Betta Fish

Why Pet Store Temperatures are Bad for Betta Fish

“But wait,” you are probably thinking. “What about all of the unheated betta bowls I see in the pet store every time I go in? Those stores keep their bettas at room temperature and they all look fine!”

Well, that’s not entirely true. Yes, they do keep their fish at room temperature but they are hardly “fine.” These bettas are very prone to disease in these conditions. Look closely and you’ll easily find fish with ich, body or fin fungus, clamped fins, excess mucus, and a listless demeanor. 

All of these become more prevalent when keeping bettas cold because they are ectothermic animals. As ectotherms their metabolism is regulated by their environment. Meaning the colder your betta water temperature the slower their metabolism becomes.

As their metabolic processes slow they eat less and their immune systems slow down. Their cells divide more slowly and they have a harder time fighting off infections.

Infections which are found in higher concentrations in the dirty, unfiltered water that betta bowls hold.

Do Betta Fish Need a Heater?

So all of this is a long-winded way of saying that bettas do need a heater. There is no good way of increasing betta water temperature without using one. Not unless you live in especially warm parts of the world like South Florida, Hawaii, or Southeast Asia, where the yearly temperatures rarely get below 70-75℉. 

Funnily enough, betta fish and other tropical fish have become invasive in these parts of the United States, including Puerto Rico. Since the year-round temperatures are so mild people can raise tropical fish in outdoor ponds, which are much cheaper than building a heated warehouse up north.

But when a storm comes by, fish can be blown from the ponds into nearby streams and ponds. So keep a close eye on your next island vacation; you might see a hearty betta swimming around alongside you!

Many betta fish diseases are partially caused by not having a heater as well. As I said earlier, betta fish metabolisms are slowed in cold conditions.

So you are much more likely to see opportunistic infections arise if your betta is kept constantly cold. A heater is not just a matter of comfort; it is also a cheap piece of insurance against possible fish diseases!

How Big of a Heater Does My Betta Need?

Choosing a heater for your betta is very easy to do. Any aquarium heater should output around 3 to 5 watts per gallon of water. If you live in a colder part of the world or have a lower room temperature then go with 5 watts of power per gallon to ensure sudden temperature swings don’t cause disease in your betta fish.

Nowadays you have many small submersible heating options for even the smallest of betta fish bowls and aquariums. These tiny heaters use next to no power. And as a benefit they keep your betta’s metabolism right where it should be to digest properly and fight off infections. So there is little reason not to keep the fish tank temperature warm using a mini-heater for your betta!

Can Betta Fish Water be Too Hot?

It is possible to increase your betta fish water temperature into readings that are too hot but that isn’t very easy to do! In fact, providing extra warm water stimulates betta to breed! Water temperatures of around 82-85℉ are ideal for this, which is the upper range of most heaters if you are using the 3 to 5 watts per gallon rule.

The only way you will overheat a betta fish aquarium is by using a heater that is too powerful and setting it to the maximum output. Nearly all modern aquarium heaters will sense when the water temperature has reached the range it has been set to and shut itself off. Once the water cools down a little the heater will kick itself back on to keep the betta fish water temperature stable.

Sometimes a heater might also short circuit, setting itself to maximum output continually. But this is very rare and more dangerous if the heater is already rated beyond the size of your betta’s aquarium.

Temperatures beyond 85℉ should be avoided as you’re getting into the stressful zone for bettas. Still, their heat tolerance is also good and even exposure to temperatures of 90℉ aren’t fatal to them.

Remember, they are found in shallow, stagnant bodies of water in tropical Asia where the direct sun can easily heat the water to this point daily. 

If you come home one day to find a malfunctioning heater has set the betta water temperature to 90℉ or more you should be quick to unplug the heater and cool the water down. I don’t recommend doing an immediate water change because we don’t want to shock the betta with cold water. 

Instead, simply unplug the heater and allow the aquarium to naturally cool. And find a new heater in the meantime so the water temperature stays in the ideal 75-85℉ range!

Should I Add a Filter to My Betta Tank?

Should I Add a Filter to My Betta Tank?

Besides a heater you should also consider adding a filter to your betta fish tank. It is unfortunate but people are often told that betta fish don’t need either when setting up a tank.

Since they are so hardy and cheap, people avoid buying a heater or filter. This usually results in a dead betta weeks or months down the line.

No animal should have to live in dirty conditions, even if they are able to tolerate them. By not providing a filter the ammonia, nitrite, and nitrate levels all rise to dangerous levels. Filters are what house the beneficial bacteria that break down these waste products safely for fish!

By using a filter you also provide much-needed aeration into your tank. Bettas are partial air-breathers thanks to their labyrinth organ. But stagnant water will result in anaerobic bacteria taking hold, which emit a sulfurous, rotten egg smell when decaying leftover food and betta fish poop.


Using a heater to keep your betta fish water temperature nice and warm is a no-brainer! Bettas are very tough and resistant to cold temperatures. But remember that they are still tropical fish at heart and do much better when kept warm.

Cold temperatures can be tolerated for a long time. But you’re slowing their metabolisms down, which will result in diseases, intestinal bloating, and other disorders.

Plus it’s just unpleasant for your fish. Who wants to be cold 24/7? Betta fish aquarium heaters are inexpensive and easy to use. So keep your betta fish healthy and happy by giving it the best situation you possibly can rather than just enough to keep it alive!

Frequently Asked Questions about Betta Fish Water Temperature

Do Betta Fish Need a Heater?

Bettas do need a heater. They are very resistant to long-term cold but should not be subjected to it for their entire lives. Without a heater keeping the water warm betta fish are much more susceptible to diseases like ich, intestinal bloat, swim bladder disorders, and fin rot. They also eat less, which further heightens their chances of getting sick.

What is the Best Betta Fish Temperature?

Betta fish water temperature should be set to between 75-85℉. A few degrees colder or warmer isn’t too big of a deal but this is the best range for them! 82-85℉ is the best temperature if you are looking to breed your betta fish!

Where are Betta Fish From?

Betta fish are from tropical Southeast Asia. Betta splendens (the Common Betta) is specifically from Thailand and they have cousin species found in neighboring countries like Myannmar, Vietnam, and Cambodia!

Jason Roberts
About Jason Roberts
Jason is an aquarium fanatic that has been a fish hobbyist for almost three decades.

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