Do Betta Fish Need a Heater? The Cost Of Fatal Mistakes

If you’ve just bought an aquarium you may be wondering do betta fish need a heater?

If you’re on the fence about buying a heater then after reading this article you’re going to find out:

  • The optimal temperature your betta fish thrive in.
  • Why temperature fluctuations are so dangerous.
  • The fatal consequences of water that is too cold.
  • How you can keep your tank warm if your heater breaks.

You can skip to any information you want using the links below!

Do Betta Fish Need A Heater?

You may have seen the pictures of bettas in tiny fish bowls or sometimes cups. And you may be questioning whether bettas need a heater or not. Well, bettas come from a tropical climate, so you can probably guess the answer yourself.

It’s essential to make sure your betta fish has a heater. Not only will it keep the temperature in the tank warm enough, it will also keep it warm CONSISTENTLY. Which is vital for avoiding temperature shock which can become fatal fast.

In fact, one study found that the best way to increase your bettas lifespan is to not only make sure they’re in a big enough tank, to also ensure that the tank is being heated enough!

How Important Is A Heater For Bettas?

If you don’t have a heater for your betta then you should buy one ASAP. All fish are extremely sensitive to the temperature in their tank, and in particular, constant fluctuations. While a cold wind or draft may be a nuisance to you, over time they can prove fatal to your betta. In fact, avoiding temperature shock is one of the best things you can do to keep your fish healthy.

The only time you can get by without a heater is if the room your tank is in remains at a constant temperature. You may think your room does this. But have you taken into consideration that the temperature of your house drops at night, and in the winter?

Heaters for your fish tank aren’t expensive and they’re well worth the investment to keep your betta healthy.

(Here’s a helpful article explaining the dangers of temperature shock as well as the symptoms and how to treat it.)

do bettas need a heater infographic

What’s The Ideal Temperature For Bettas?

The ideal temperature range in a betta tank is 78-80°F. This is the temperature that is going to help keep your betta in optimum health. However, bettas will remain healthy anywhere between 76-82°F. The danger comes when your temperature becomes too low or too high.

If the temperature of your tank drops below 74°F or goes above 85°F then it’s going to severely impact your betta’s health.

Most tropical fish are going to fit somewhere nicely in between these two wider temperatures as well.

(Find out more about the ideal temperature for bettas, such as what happens when it fluctuates, becomes too hot or too cold.)

What Will Happen If Your Betta Gets Too Cold?

When your betta is in water that is below 74°F you’re going to cause them serious distress and eventually they will die.

The first thing you will notice when your tanks temperature begins to drop is your betta becoming sluggish. This is because his metabolism is slowing down as he tries to conserve energy.

As your betta increasingly becomes more stressed you’ll notice him stop eating. The whole time this is happening his immune system is also weakening because of the added stress on his body.

You’ll begin to notice the color fading from his skin and scales.

He may try to stay near the bottom of the tank or where any heat is.

But, it won’t help. Now that his immune system is low he’ll be more prone to a bacterial or fungal infection.

Some of the diseases and bacterial infections such as fin rot will be relatively easy to cure if you get the temperature back up and follow a proper care guide, like the one you can find here. Or they could get a disease which is more serious like dropsy.

As you can see, leaving your betta in a tank that full of cold water is extremely cruel. And if your not 100% certain you can maintain a constant water temperature without a heater then you need to get one.

betta fish

What Will Happen If A Betta Gets Too Hot?

If you’re curious about what will happen when a betta gets too hot, then the truth is over 85°F your betta will slowly begin to start overheating.

The first signs you’ll notice is your fish swimming erratically. Fish are cold-blooded animals and can only stay at the same temperature as their surroundings. The added heat will give them more energy. This sounds like a positive but actually, it will cause your fish massive stress weakening their immune system.

If you’re tank is getting too hot there are solutions. One thing you can do is let a fan blow over the top of the water. This is going to cause evaporation to happen at a faster rate keeping your tank colder.

And remember, in smaller tanks, it won’t take much for the tank to overheat. In fact, even direct sunlight, on a small tank can heat it up rapidly.

What Size Heater Should You Get For Your Betta’s Tank?

To ensure there is warm water in your bettas tank at all times, you should choose a heater that has 5 watts of power per gallon of water. For example, a 10 gallon tank will need a 50 watt heater, a 15 gallon tank will need a 75 watt heater and so on.

I’ve found that when you get to much larger tanks, a good idea is to simply add more than one filter to the tank. They won’t overheat the tank, as once the desired temperature is reached, they’ll just turn off.

Why You Should Consider Getting A Bigger Tank

If you had a cup of boiling water or a bath of boiling water, what one would cool down first?

Obviously, the temperature of the cup would drop a lot quicker than the baths. And that’s the exact same reason you should consider a good size tank.

Even though the recommended minimum for bettas is 2.5 gallons, a smaller tank is more susceptible to faster, drastic temperature changes. (And they also need to be cleaned more regularly.) I personally would never go any lower than 5 gallons for a betta.

Once you start to get tanks that are 5 gallons or higher, it’s a lot easier for the tank water to stay at a constant temperature. Even if you have an aquarium heater in a 2.5-gallon tank a sudden drop in room temperature is still going to have a big effect on it.

(Check out the best tanks for betta fish.)

What Are The Different Heaters For Your Aquarium?

Before you go out and buy a heater for your aquarium, there are a number of different heater types you can choose from. Here are the four types of aquarium heaters:

Type of HeaterDescriptionAttachment MethodProsCons
Immersible HeatersHeating element in a glass tube, partially submerged. Control knob above water.Mounted at the top with a bracket.Easy to control temperature.Affected by room temperature. Temperamental.
Submersible HeatersFully submerged in the aquarium.Suction cups to aquarium glass.Consistent heating. Unaffected by room temperature.Risk of breaking if left out of water.
Substrate HeatersLocated under the substrate, ideal for planted aquariums.N/AEncourages plant root growth.Not commonly used for betta tanks.
Filter (In-line) HeatersAttached to the external filtration system.N/AEven heat distribution. Good for large tanks.Stops working if the filter stops.

Immersion Heaters

Immersible heaters, sometimes referred to as “hang-on” heaters have a heating element encased in a glass tube, which remains partially submerged in the aquarium water. The control knob, however, allowing you to change the temperature easily.

Immersible heaters need to be mounted at the top of the aquarium with the help of a bracket. However, a key point to remember is that temperature fluctuations within your room can affect their efficiency, similar to the case where your betta tank is left without a heater. These heaters do not typically use suction cups for attachment.

Immersion heater’s aren’t the most popular choice, because they can be a bit temperamental. In fact, I’d recommend avoiding immersible heaters, and sticking to the following:

Submersible Heaters

Submersible heaters, as the name suggests, can be completely submerged in your aquarium. They use suction cups to stick to the aquarium glass and can be positioned either horizontally or vertically depending on your preference.

Submersible heaters provide more consistent heating as they are not affected by room temperature changes, however, if you leave the out of water while they’re on, it’s possible they’ll break. So keep an eye on the tanks water level!

They are a reliable solution for maintaining stable water temperatures and preventing harmful temperature shocks to your betta fish.

I personally use a submersible heater, with great results. If you’re interested in my top choice, then it has to be the Fluval M Series. I have a 10 gallon tank, so I use the M50.

Fluval M50 Ultra-Slim Submersible Aquarium Heater – 50W Underwater Heater for Aquariums up to 15 Gal.
  • Modern Aesthetic: M-Series heaters combine modern aesthetics with reliable Italian construction. Employing an ultra-slim profile, these heaters are a welcome departure from traditional, bulkier designs.

Substrate Heaters

Substrate heaters, often used in planted aquariums, as you can guess, go under the substrate. By heating the substrate, they encourage plant root growth by circulating water in the substrate, improving nutrient uptake.

While these heaters aren’t typically used in betta tanks, if you have a planted setup, they’re still a great choice.

Filter Heaters

Lastly, filter or in-line heaters are attached to the external filtration system of the aquarium.

With in-line heaters the water is heated as it flows through the filter and returns to the tank, ensuring an even distribution of heat. This type of heater is especially beneficial if you have a large aquarium or one with multiple fish.

However, one thing to note about in-line heaters is that they only work while the filter is working. If the filter stops, then the in-line heater won’t work at all. This double whammy could prove fatal fast if something goes wrong.

Now you know all the heater choices, I’d still recommend a submersible heater, however, you should decide based on your own individual needs.

How to Heat a Betta Fish Tank in an Emergency

If you have a heater for your fish tank, at some point there may be an emergency. The heater might break or there could be a power cut. Whatever it is, when the times come you may be wondering how you can keep your tank warm.

Once again having a bigger tank will benefit you in this situation. The water will take longer to cool down, giving you more time to come up with a solution. Some common solutions are:

  1. Turning up the heating in your house. This can work if you know it won’t be long before you can heat your tank again, or if you’re using a small tank. By heating your house, you’re going to stop the room temperature lowering the water temperature.
  2. Make sure you move your tank away from any windows and get it closer to the center of your house. Heat is lost through windows, so areas of your house near windows can often be cooler.
  3. However, if it’s a sunny day, and quite warm outside you might consider doing the opposite. Leaving your tank in the sun is going to heat the water up. Just make sure it doesn’t get too hot.
  4. Get some hot water and place it in a bag. (10% of the size of your tank should be enough). Make sure the bag is warm but not boiling. Take 10% of the water out of your aquarium and place the bag in. Then just let the bag float on the top of your tank.
  5. If your tank is open topped then you can place a towel over the top to help keep the heat in. This can also keep heat in when you do have a lid. Heat rises, and putting a towel over your tank is going to keep the heat in.
  6. On the subject of towels, you can also wrap towels around your tank to keep the heat in as well. While the sudden light change may stress your betta a little, it’s still not going to be as stressful as a water temperature drop.
  7. Try using other household items that create heat. For example, you could move a lamp near your tank and focus light on it, or you could aim a hairdryer at your tank. Obviously, these are short term solutions but they can be useful while you’re looking for a more permanent solution.
  8. Another great choice if your heater has broken is to wrap your tank in an electric blanket. Just make sure you’re monitoring the temperature of your tank carefully.
  9. Set up candles around your tank. Tea lights work best. If you put enough around your tank, the heat from the flames is going to be enough to keep the water in your tank warm.

These are just some of the ideas I’ve come up with off the top of my head. If you have any ideas you should try them too. The most important thing is to make sure you’re monitoring the temperature of your tank and making sure that it’s not rising or falling to significantly.

How Long Will A Betta Survive Without A Heater?

There are so many different factors that go into whether a betta can survive without a heater. For example, if the temperature of your room is above 78°F then your betta is probably going to last a long time. But if it’s too cold or your betta is already sick then it can be a matter of days before your betta becomes extremely unhealthy. But once again there are so many factors that should be taken into consideration such as room temperature, the age of your betta, how healthy your betta is, how quickly the water temperature is dropping etc.

To master the art of betta fish care, you need a comprehensive guide. Click here to read one!

What Else Should Your Betta’s Tank Have?

As well as a heater, filters and thermometers are also essential for your bettas health.

A thermometer will simply allow you to check that the water is the temperature it should be so you know everything is alright. A filter, however, is much more essential.

Filters are going to create a place for beneficial bacteria to live. This bacteria will keep the ammonia, nitrite, and nitrate levels in the aquarium water low, improving the water quality.

Do You Have A Better Understanding Now?

So, do betta fish need a heater?

After reading this article you should have a better understanding of why it’s so important for your betta fish to have a heater. Just as a quick reminder here are the most important things you need to know.

  • The ideal temperature for betta fish is between 78-80°F. This is the temperature in which they will really thrive. However, if your tanks temperature is between 74-85°F they will still stay healthy.
  • When the temperature of your tank drops below 74°F then your fish will start to suffer. His immune system will weaken and the most likely outcome will be a disease and then death.
  • If your tank goes over 85°F then your fish will start overheating, causing stress and eventually death.
  • One of the best ways you can keep your fish tank at a stable temperature is to get a bigger one (minimum of 5 gallons). When there’s more water in a tank it’s harder for the temperature to fluctuate as much.
  • If your heater breaks there are a number of things you can do to keep it warm. Such as floating a bag of hot water in it, wrapping it in an electric blanket and moving it somewhere warmer.
  • If your heater does break it doesn’t mean your betta will get sick straight away. There are a lot of factors that will also contribute such as age and the current strength of your bettas immune system.
Do Betta Fish Need a Heater

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