Ideal Guppy Water Temperature (Min, Max, What Can Go Wrong)

Maintaining the right water temperature for your Guppies is crucial for their health and happiness. Guppies thrive in warm water, making them ideal for tropical fish tanks.

But before you can keep your aquarium heated to the appropriate temperature, you have to know the right parameters. So, in this article, we’ll learn everything about Guppies’ water temperature and more! Keep reading!

Key Takeaways:

  • Ideal Guppy Water Temperature Range: 74 to 82 F (23 to 28 C)
  • Guppies can tolerate lower temperatures, down to the lower 60s, but prolonged exposure can lead to stress and weakened immune systems.
  • Maximum survivable temperature for guppies is 90 F (32 C), beyond which they may experience stress, disease susceptibility, and oxygen deficiency.
  • Effects of Hot Water on Guppies: Increased metabolism, stress, weakened immune system, potential lack of oxygen, and problems with beneficial bacteria.
  • Minimum Temperature Guppies Can Survive: Should not be kept in water lower than 60 F (16 C).

What Is The Ideal Guppy Water Temperature Range?

If you’re wondering what the ideal temperature range for guppies is then wonder no more!

The ideal temperature range for a guppy’s water is between 74 and 82 F (23 to 28 C). Which is also the ideal temperature range for most fish tanks.

This is part of the reason why they can easily cohabitate with other fish. When temperatures drop, they can withstand water in the lower 60s.

What’s The Maximum Temperature Guppies Can Survive In?

The maximum temperature that a guppy can survive in is 90 F (32 C). When the water reaches this temperature, they can only stay in it for a short time period. 

What Will Happen If Guppies Stay In A Tank That’s Too Hot?

When the water in a guppy’s tank becomes too hot, its metabolism begins to speed up, which causes the Guppy to become more hyperactive. All that extra movement can cause guppy stress, and stress is one of the biggest killers of aquarium fish. This is because all of that additional stress from movement can weaken their immune system.

Your Guppy doesn’t have to be exposed to temperature shifts for long to be affected by disease or even parasites. This is why it’s a good idea to keep an eye on your thermometer to make sure their water stays within the ideal range. A fish that is stressed due to temperature is at higher risk of being a target for diseases and parasites.

Another scary thing that could happen if temperatures become too hot is a lack of oxygen. Fish breathe oxygen that’s drawn from the water, and hot water isn’t able to hold as much oxygen. If the temperature gets too high, there might not be enough oxygen to go around the aquarium. This could cause your guppies to suffocate. 

To make matters even worse, every fish tank has beneficial bacteria in the water. If the water temperature is too high, the bacteria won’t get the oxygen needed to break down ammonia in the tank. When ammonia builds up in the tank, it can cause all sorts of problems, including burning the Guppy’s gills. 

What’s The Minimum Temperature Guppies Can Survive In? (Can Guppies Live In Cold Water?)

Temperature RangeEffects on Guppies
74 – 82 F (23 – 28 C)Ideal range for health and happiness; suitable for most fish tanks.
Below 60 F (16 C)Prolonged exposure can lead to stress, weakened immune systems.
90 F (32 C)Maximum survivable temperature; beyond this, stress, disease susceptibility, and oxygen deficiency may occur.

Guppies are tropical fish that are used to warmer climates. This means that they should never be kept in water that’s lower than 60 F (16 C). That being said, guppies can survive if temperatures drop that low and are not meant to live in cold water.

What Will Happen If Guppies Stay In A Tank That’s Too Cold?

You should never keep your guppies in a tank that’s too cold because that’s an open invitation for many problems. Coldwater will lower their activity level, and from there, more issues arise. One of the biggest problems with cold tanks is that they will experience breeding problems or even stop breeding altogether. 

Guppies need warmer temperature ranges to survive, which means staying in a cold tank puts them at a higher risk of catching diseases. Some of the diseases they are susceptible to could lead to their death. How guppies feel in a cold tank is how you would feel if you went outside in the winter without a jacket, hat, or mittens.

Now that you have an idea of how a guppy will feel once it’s in a cold tank, you’ll have a better perspective of why they need a certain temperature range. In the wild, when the water temperatures drop, the fish has the option to swim to warmer waters. They are unable to do that in an aquarium, so you will need to keep their temperature in the ideal range.

Can You Keep Guppies In The Outside Pond?

Guppies love pond water and can do very well in it, especially if you live in a warmer climate. If the pond water doesn’t drop below 68 F (20 C) during the coldest point of the year, then it is a safe spot for your guppies to live. However, if it gets colder than that, you can still allow them in the pond under certain guidelines. 

If the temperatures get colder than that, then your guppies can only go outside during the warmer seasons. You will have to wait until the water is consistently above 64 F (18 C) before you bring the fish outside. As long as the water temperature doesn’t drop below that at any point in the day, then it’s safe to bring your guppies to the pond.

In most climates, it’s safe to leave the guppies outside from late spring throughout the summer. Even though the temperature in the air may drop at night, the sun heats up the water enough during the day to keep it consistently warm all night. However, you will need to bring the Guppy back inside to controlled temperatures once autumn arrives. 

What To Do If The Water Is Too Cold In The Guppy Tank?

Always keep a thermometer in your aquarium so you can keep an eye on the temperature range. If the temperature in your Guppy’s tank starts to drop below 74 F, then you will need to take action, so the guppies don’t get sick. Your aquarium will need a heater to control the temperature, but you must have the right size of heater for your tank.

If your heater doesn’t have the correct watts for your tank size, then it may not be heating the water up enough. These are the ideal heaters for each tank size:

  • 25 Watts for 5 gallons (20L)
  • 50 W for 10 gallons (40L)
  • 100 W for 20 gallons (80L)
  • 125 W for 25 gallons (95L)
  • 200 W for 40 gallons (150L)
  • 250 W for 50 gallons (190L)
  • Use two 200 W heaters for 65 gallons (250L)
  • Use two 300 W heaters for 75 gallons (285L)

With the right wattage, you should have no trouble making sure your guppies have the right water temperature range. Remember, controlled temperature is the key to keeping your guppies happy and healthy.  

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What To Do If The Water Is Too Hot In The Guppy Tank?

If the water gets too hot, then your guppies might not be able to breathe. This is a situation you’ll want to fix as soon as you notice it. Sometimes the summer heat can be unfriendly, and if the temperature inside your home is too hot, there’s a good chance your fish tank will be uncomfortably warm.

When the water starts to get higher than 82 F, it’s time to take action. If you have controlled heating and cooling in your home, turn the air conditioning on so things cool down inside. The sun that’s beaming in through your windows may seem nice, but it’s also heating up the water in your tank. Try to cover all the windows with blinds to keep the sun out.

Lights actually provide a fair amount of heat themselves, so it’s a good idea to temporarily turn off the aquarium lights, as well as the lights inside the room your tank is in. Try to keep things as dark as possible until the water cools down. 

So the heat doesn’t stay trapped in the tank, it’s a good idea to remove the lid. You will have to be careful if any of your fish have a tendency to jump. If you have a cat, make sure they are kept in a separate room. This will help release some of the heat so the water can carry oxygen again.

Now that you have the lid off, there are a few things you can do to help cool the water down quicker for your guppies. Do you have a fan that blows cool air? Set it up, so it’s facing the top of your fish tank, and turn it on to cool things off. You may have to set it on a chair or stool to get the right height.  

Another thing you can do to cool the water down is put some floating ice packs on top of the water and let them set. You don’t want to shock the fish by making things too cold, so don’t add ice cubes directly into the water. Only choose ice packs that float.

Check out this video b Guppy Channel on everything you need to know about Guppies’ ideal temperature!

Is It Dangerous To Cool Down A Guppy’s Water?

When you’re changing the temperature of a guppy’s water, it’s important to do it slowly. Rapid temperature changes could actually do more harm than good for the fish. In order to keep things as safe as possible, you should only change the water’s temperature by 2 degrees F (1C) every 8 or 10 hours. 

This is why it’s very important to monitor the temperature in your aquarium, especially when temperatures start to change. If you aren’t prepared for a heatwave, then your guppies could suffer. 

Should You Keep A Guppy’s Tank By The Window?

Guppies will love it if you keep their tank near a window, especially if you live in a colder climate. The only time this poses a risk is during a summer heatwave, and even then, you can prevent overheating by using blinds or curtains. In the cooler months, your guppies will love the extra heat and most likely be more active. 

Should You Keep A Guppy’s Tank By A Radiator?

We don’t recommend placing your Guppy’s tank beside a radiator. Although this will keep them nice and warm in the winter, it poses a threat because of constant temperature changes. Guppies don’t react well to constant changes in temperature, so if their water’s temperature keeps going up and then cooling off, they could become ill. 

In order to keep a guppy happy and healthy, they need to be in a warm environment, but it has to stay at a consistent temperature. If a guppy’s water needs to increase by 3 degrees, then that needs to happen gradually. They can’t have you heating their water up an additional 3 degrees in a few minutes. 

Make sure you place your aquarium in an area where the radiator won’t affect it. 

Regulate The Temperature In Your Home

Heating can be pricey, especially in the wintertime. This is why so many people like to turn their central heat off when they go to bed or when they leave for work. While this may save you money on your heating bill, it makes things difficult for the fish. While keeping your Guppy’s water within proper range is important, making sure the temperature is consistent is more important. 

Some people have made the mistake of turning off the heat when they went away for a few days. They thought everything would be fine, only to come back home and find out their guppies didn’t do so well with the temperature change. While it’s okay to turn down the temperature a little bit when you leave, you should avoid turning your heat off in winter.

How Many Guppies Can Fit In A Tank?

The number of guppies that are suitable for a tank depends on how many gallons of water it holds. Too many guppies in the tank could affect the water quality, and also raise the temperature of the water. The rule of thumb is 1 gallon of water for every 1 inch of fish.

On average, guppies grow to be anywhere from half an inch to just over 2 inches. Many people find that a 5-gallon tank provides just enough room for 3 or 4 guppies. However, this will all depend on how big they are. 

What Type Of Water Do Guppies Like?

While we know the preferred temperature range, it’s also helpful to know what type of water guppies live in. Guppies do better in hard water with a pH balance of 6.8 to 7.8. This makes things easier for a lot of people because most towns’ tap water has a pH balance of 7.6. That is the perfect balance for guppies to thrive.

Will Changing The Guppy’s Water Effect The Temperature?

It’s really important to keep your Guppy’s water clean, so they aren’t swimming around in their own waste.

If your Guppy is swimming upside down, however, It can be a sign of something else. Find out what it means here!. However, you’ll want to do this carefully because you won’t be able to guarantee the clean water you add to the tank will be the same temperature as the water you remove. 

In order to keep the Guppy’s water temperature consistent, we recommend only changing 30 percent of the water at a time. Do this once a week to keep things clean for the fish. Changing out a small amount each time allows you to keep the water clean without disrupting the guppies.

Since tap water is known to have traces of chlorine in it, we recommend pouring the amount you want to add to the tank into an open container and letting it sit for 24 hours. This will give enough time for the chlorine to evaporate, so it doesn’t affect the Guppy’s water. The water will also warm up to room temperature during this period, making it safer to add.

How Will I Know If I Need A Heater?

Unless you live in a tropical environment, it’s necessary to have a heater on your fish tank. Guppies are native to the Amazon, where the temperature never drops below 73 F. They cannot survive in the cold temperatures that people face in North American and the UK. 

In order to make your guppies feel like they are at home, you need to have a heater for your guppies. If you don’t keep their water warm enough, they will be at risk for many diseases. They also benefit from bright light during the day, for at least 8 hours. This is especially crucial if you have plants in the tank for your guppies. 


At What Temperature Do Guppies Die?

Guppies usually get sick or die when the temperature drops below 70°F. Some guppy keepers have experimented with cooler water, around 60°F, but it’s not recommended. When the water gets below 68°F, your guppies may become sluggish, eat less, and stop breeding. If the water is 60°F or lower, it’s time for a change.

Conclusion: Ideal Guppy Water Temperature

Guppies are such easy-going fish, and they really don’t require much to be happy. However, if their water isn’t in the right temperature range, then they could be at risk of many problems, including diseases. Guppies always thrive when they are living in water that’s similar to where they originate from.

Since guppies come from tropical environments, their ideal water range is between 74 F and 82 F. This is a pretty wide range. The most important thing to remember is that guppies need a consistent temperature to stay healthy. Don’t change their temperature to more than 2 degrees within a day.



About the author

Hey there! I'm Antonio, the passionate owner and chief editor of Betta Care Fish Guide. With over half a decade of hands-on experience, I've become your go-to expert for all things betta and tropical fish.

Over the past 5 years, I've not only kept bettas and other tropical fish but also connected with a diverse network of hobbyists, seasoned fishkeepers, and even veterinarians.

Now, I want to help other beginner fish keepers who had the same questions as me when they were just starting out! So they can save themselves a ton of time and keep their fish happy and healthy!