Do Betta Fish Need a Heater? Read To Find Out!




Do Betta Fish Need a Heater

Sharing is caring!

Bettas are well sought after for being hardy, beautiful, tropical aquarium fish. You can ensure that your betta has a long lifespan by making sure they have the proper tank setup with a heating system. Your bettas will not only live longer but they will be healthier in the long run.

How Important Is a Heater?

Just like other fish, bettas are sensitive to temperature swings. These temperature swings can even be fatal for your fish. Avoiding temperature shock is important for keeping your fish healthy.

The only case in which you don’t need a heater is if the room you are housing your fish tank in remains at a constant temperature, but this is very rare. Heaters are well worth it to keep your betta healthy and they are also often inexpensive.

What Is the Proper Water Temperature?

The water temperature range for bettas is between 76 and 81 degrees Fahrenheit. This fish species can survive in temperatures lower than this, but this will cause them stress and weaken their immune system. A weakened immune system can cause illnesses to occur, including:

  • Bacterial infections like “Fur Coat Syndrome”
  • Ich
  • Mouth fungus and fin rot

They can also handle warm temperatures up to 82 degrees. A high temperature is sometimes needed in a hospital tank when treating an infection, but this temperature is not best for them in the long term.

What Happens When Fish Get Cold?

Bettas do not have a cold-water fish’s ability to survive the cold because they are tropical fish. They can only survive cool temperatures for a short time.

Bettas are cold-blooded animals, meaning their body temperature matches the water that they live in. Colder temperatures can bring death in just minutes.

Signs Your Fish Is Too Cold:

  • Slow swimming
  • Staying close to the heater or a warm part of the tank
  • Loss of color
  • Increased illness

What Is the Lowest Temperature a Betta Fish Can Live In?

The lowest temperature betta fish can survive in is 72 degrees. Any lower than this will increase their chances of illness and then death for bettas can occur within hours.

How Long Can My Betta Live in Cold Water?

The answer to this depends on how cold the water is. If the water is at room temperature it can survive between 3 and 6 months. The colder the water the less time your betta can survive in that environment. It could be minutes or hours.

What Will Happen If Your Fish Gets Too Hot?

This might sound like common knowledge, but when your fish get too hot, they start to overheat. The first sign your fish is overheating is erratic swimming.

Just like when the water is too cold, hot water will cause them lots of stress and weaken their immune system. If your water gets too hot, you can let a fan blow over the top of the water to cause evaporation and lower the tank temperature.

A Constant Temperature Is Ideal

Besides keeping the temperature in the correct range, bettas do well when the temperature is consistent. If the temperature swings a couple of degrees during the course of the day or the change in seasons, this shouldn’t cause any harm. However, an eight-degree swing in a day is worse for your fish than a constant temperature outside of the ideal range.

Consider a Bigger Tank

The recommended minimum betta fish tank size is 2.5 gallons. However, the smaller the tank the more it is likely to experience quick, drastic temperature changes.

If you instead keep a tank of 5 gallons or larger it is easier to maintain a constant water temperature and it will also need less cleaning. Larger tanks will take longer for the water temperature to fluctuate.

Do Betta Fish Need a Heater

How To Choose the Best Heater

There are so many different aquarium heaters out there, it can be hard to know what to choose. Here are some tips on choosing the right heater for your betta.

Heaters With a Thermostat

It’s easy to overheat the aquarium water if you buy a fish tank heater without a thermostat. It’s also easy to do if you have a small tank.

The thermostat will turn off the heater once it reaches the optimal temperature and prevent the tank from overheating and causing your fish to become stressed and sick.

Fully Submersible Heaters

A fully submersible heater is more efficient than other heaters. Also, if you buy a heater that isn’t fully submersible you run the risk of accidentally dropping it into the tank, which can lead to electric shock among other things.

Glass vs Plastic

Glass thermometers are typically more efficient heaters and are easier to clean. Plastic can become discolored over time and look clunky.

Other Important Considerations

When choosing a heater for your aquarium tank, other things to consider include:

  • Choose a heater that gives off 3–5 watts of power per gallon of water
  • Make sure it will fit comfortably in the tank
  • Ensure the heater is strong enough to heat the tank if placed in one corner
  • If you choose a heater that isn’t fully submersible, make sure it is attached to the tank with a screw to prevent it from falling into the water.

Safe Operation

There are a few rules for safe heater operation to keep you and your aquarium fish safe.

  • Install a thermometer or possibly more than one in a large tank
  • Monitor the fish tank water temperature every few hours. Heaters can be faulty, and you will want to catch them as soon as possible.
  • Allow the heater to set up for an hour in the water before plugging it in. This will prevent possible cracking of the glass. For more info on how to set up a heater, watch this video.
  • Read the manual to find out how your thermostat works. If an adjustment is made too high and it isn’t monitored, the heater can increase the temperature in the aquarium and kill your fish.
  • If you are using a semi-submersible heater, check the waterline marking based on the water level in the aquarium and make sure the water doesn’t go above or below the marker. If the water level is above the line, it can lead to electric shock, and below the line can cause the heater to explode by overheating.

How To Heat Your Tank in an Emergency

If you’re using a heater to maintain a stable temperature in your tank, at some point there is bound to be an emergency. Your heater could break, or the power could go out. Until the power outage is over or you can get a new heater, you may be wondering how to keep your tank supplied with warm water.

Some common solutions include:

  • Having a bigger tank. If you have a bigger tank, it will take the water longer to cool down and give you more time to work out a solution.
  • Turn up the heat in your house. If you can stop the room temperature from lowering your tank may be able to maintain the water temperature for a short time.
  • Move your tank away from windows so it doesn’t lose heat depending on the temperature. If it is a warm day, moving your tank towards a window can help maintain the water temperature. Make sure your tank water doesn’t get too hot, however.
  • Place hot water in a bag or water bottle. Ensure that the water isn’t boiling but is warm. Let the bag or water bottle float in your tank.
  • If you have an open-top tank you can put a towel over the top to hold in the heat. This can also work for a tank with a lid.
  • You can also wrap towels around your tank.
  • You can move a lamp near your tank for heat.
  • You can wrap your tank in an electric blanket, but you’ll have to monitor the temperature closely.
  • Use candles around your tank. The heat from the flames may be enough to keep the water warm. Make sure to use a candle that doesn’t release much soot or odor. Tea lights are a good option if you’re using this method.

While these methods aren’t 100 percent perfect, they can help to reduce the chance of stress to your fish and keep your fish alive until heat can be provided.

How Long Can Betta Fish Survive Without a Heater?

There are several aspects that affect how long a betta can live without a heater.

If the temperature of the room is above 78 degrees and is stable, it could last a long while without a heater. If the temperature is too low and your betta is already sick, it may only survive a few days.

To decide how long they can truly live without a heater, you have to take into account how quickly the water temperature will drop, the health of your betta, betta age, room temperature, etc.


The bottom line is that your betta fish need a heater. Maintaining the proper water temperature range for your betta fish is crucial.

Temperature fluctuations can make your betta fish sick and if the fluctuation is drastic enough it can cause death within hours.

A heater is a simple and inexpensive option to keep your betta fish warm, happy, and healthy.

Sharing is caring!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.