Do Guppies Need a Heater?

Guppies are the perfect fish for both beginners and long-time fish owners. However, to make sure the fish are happy and healthy, it’s important that a few things are attended to. This includes ensuring the tank’s water is the correct temperature. 

Guppies do need a heater because they are tropical fish. Because of this, their body needs to stay warm at all times. 

Below is more information about why guppies need a heater and how you can make sure their water stays at the correct temperature. 

Why Do Guppies Need Warm Water? Can Guppies Live in Cold Water?

Guppies need warm water because they are tropical fish. Guppies are native to South America and live in waterways near countries such as Barbados, Brazil, and Trinidad and Tobago. Because of this, their body needs warm water in order to survive. 

While guppies can sometimes live in cold water, it isn’t ideal. This is because it can stress their body and cause them to get hypothermia. 

Can Guppies Live Without a Heater?

So, can guppies live without a heater? No, guppies absolutely need a heater in order to survive. Otherwise, their body will get too cold which can cause them to get very ill. While guppies can sometimes live in water as low as 60 degrees Fahrenheit, this is not good to keep them in. The cold water will often cause them to become depressed.

What Temperature Can Guppies Survive In? What Temperature is Best for Guppies?

The right water temperature for guppies is about 78 degrees Fahrenheit. The water shouldn’t go beyond 82 degrees Fahrenheit as it could make your fish’s metabolism too fast, which shortens the fish’s lifespan. Because of this, you want to make sure to keep the temperature between 74-82 degrees Fahrenheit. On the other hand, increasing the temperature to 84 degrees Fahrenheit will help inspire guppies to breed.

What Temperature Do Guppies Need: Can Guppies Live in 85-Degree Water?

Some believe that because guppies are tropical fish they enjoy extremely hot water temperatures. While guppies do prefer warm water, 85 degrees can be a little too hot for them. While it might not be fatal for the guppies, it could make them feel a little sluggish. 

How Do I Know When the Temperature is Too Hot or Cold?

There are a few signs you can use to tell if the fish tank is too hot or cold. 

  • There is rapid gill movement with your fish (a sign they are gasping for air).
  • The fish are floating toward the surface of the water. 
  • They are acting sluggish and sleepy. 
  • The fish are acting extremely hyper. 
  • They aren’t eating. 

If you find that your guppies are showing these signs, their water temperature is probably incorrect. Due to this, you need to quickly fix it or could end up being deadly for them. 

Testing the Temperature of the Water

To ensure that the water temperature of the tank is right you need to test it. There are a few ways you can do this. 

Use a Thermometer

A simple way to test the water temperature of the tank is to use a thermometer. Simply put the thermometer into the water for a few minutes. This will give you a somewhat accurate reading of the water and tell you whether you need to increase or decrease the temperature. 

You can use two types of thermometers to help with this. One is a traditional thermometer which you stick into the water. The other is a thermometer with a suction cup that you can place on the side of the fish tank. This will allow you to quickly see the temperature of the tank at all times. 

Test it With Your Hand

Another method to test the temperature of the water is to use your hand. By dipping your hand into the water, you’ll be able to feel if it’s cold, lukewarm, or hot. If it feels like the temperature might be incorrect you’ll need to quickly change it. 

Types of Fish Tank Heaters

There are a handful of fish tank heaters you can choose from. 


This type of heater is to be put in the tank’s water. They can be attached to the tank with suction cups. This heater should be placed horizontally in the tank. 


An immersible fish tank heater can be placed on the top of the tank but isn’t able to be put into the water. This type is good for those who want easy access to the heater. 


This fish tank heater works as both a filter and heater. A filter heater is ideal if you want to ensure the tank’s water is clean and warm for your guppies. However, this type can be a little pricey. 


A substrate fish tank is put beneath the bottom layer of sand in the tank. The heater then sends warmth throughout the tank. This fish tank heater can also benefit any aquatic plants you have in the fish tank because it encourages the roots to grow. 

What Type of Heater is Good for My Fish Tank?

The right type of heater for your fish tank depends mainly on the size of your tank. For instance, if you have a small tank (around 15 gallons) a heater with lower wattage is good. On the other hand, if you have a large tank (about 150 gallons) a stronger wattage is best. 

If you’re still unsure as to what the right wattage is for your tank, you can use an online aquarium heater calculator. This calculator will determine the right type to get based on the dimensions and material of the tank. 

Installing a Fish Tank Heater

While the right way to install a fish tank heater depends on the model you buy, there are a few general tips you can keep in mind. 

Look for a Suitable Spot

The first step is to look for the right installation spot in the fish tank. This way, you can be sure the heater will work well for the tank and won’t disturb your guppies. 

Let it Sit in the Water for a Few Minutes

After you put the heater in you want to let it sit in the water for a bit. This will help the heater to get used to the water, something which can prevent it from breaking. 

Turn the Heater On

After you install the heater and let it sit you want to then turn it on. You should start at a low temperature and then gradually increase it. It’s important to constantly check the heater during the first 24 hours to ensure it’s working properly. This will also help you to prevent your fish from being stressed due to a new living environment. 

How Can I Keep My Tank Warm Without a Heater?

While a heater is ideal to use, if you don’t want to put one in your fish tank there are a few other options available. 

Put the Tank in a Warm Spot

For those who prefer not to use a heater, you could instead install the fish tank in a consistently warm area. By doing so, sunlight will heat the water to a comfortable temperature for your fish. However, it’s important to take care when doing this as sometimes the sun could end up warming up the water too much. If the water ends up getting too hot, it could make your fish very sick and could prove to be fatal. Because of this, it’s important to monitor the water temperature daily. 

Besides sunlight, you can also increase the temperature of the room the fish tank is in. This method can be especially helpful during the winter. 

Wrap the Tank in Towels

Another way to keep your fish tank warm is to wrap it in towels. While this isn’t a permanent solution, it can help to ensure your fish stay warm for a few hours. You can also wrap the tank in towels at night. This will keep the tank warm when you turn the lights off or if the room tends to be a little cold during the evening. Besides keeping the tank slightly warm, the towels will create a dark environment for your fish so they sleep easily. 

Install an Aquarium Light

Aquarium lights are meant to help illuminate the fish tank. It also encourages photosynthetic life to thrive in the tank. However, an aquarium light can be very helpful in keeping the fish tank warm. 

While this is a helpful way to keep the tank warm, it’s important to not run it often. This is because the light could overheat which could cause a fire. Because of this, it’s ideal to run the light for a few minutes so it slightly warms the water up. Afterward, turn it off. 

Guppies are easy fish to care for but it’s vital that their water is at the correct temperature. Otherwise, it could make them very sick and could even kill them. Because of this, it’s important to use a heater in their tank. However, in the case of emergencies, other heating methods can be used, like blankets.