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Beginners Guide

Guppy Water Temperature - All Things About Temp For Your Guppy’s Tank

by Nguyễn Hoàng Anh Tuấn 15 Apr 2023 0 Comments


Guppies are among the most popular tropical fish people keep in their home aquariums. These fish are well-suited for their friendly personalities, and they won't disturb the other fish in your community tank. These little fish will thrive if your aquarium has the ideal water temperature for guppies. They are brightly coloured fish that are often active in the tank. Many hobbyists consider them a great pet choice because they are easy to keep.

As long as you feed them and keep the water at the right temperature, they will live happily. We often call them rainbow fish because no two guppies are alike. Another reason for this name is their colourful scales.

What is the maximum temperature guppies can survive?

Since these tropical fish do not do well in colder waters, the optimal temperature range for guppy water is from 74℉ to 82℉. That's also the ideal temperature range for most aquariums. When the temperature drops, they can withstand water at 60℉. This is part of why they can quickly get along with other fish.

The maximum temperature that guppies can survive is 90℉. When the water reaches this temperature, it can only stay in briefly.

What happens if the guppies in the tank are too hot?


When the water in a guppies tank becomes too hot, its metabolism accelerates, causing the guppies to become more hyperactive. All those extra movements can cause stress for guppies. This is because all the additional stress caused by exercise can weaken their immune system.

Fish breathe oxygen from water; hot water cannot hold much oxygen. If the temperature becomes too hot, it will lead to a lack of oxygen in the water. If the temperature is too high, there may not be enough oxygen to get around the aquarium. This can cause your guppies to suffocate.

Every aquarium has beneficial bacteria in the water; if the water temperature is too high, the bacteria won't get the oxygen it needs to break down the ammonia in the tank. If you leave the water temperature high for too long, you put guppies at risk of fin and tail rot from ammonia burns. When ammonia builds up in the tank, it can cause many problems, including burning guppies' gills.

What is the minimum temperature guppies can survive?

Guppies are tropical fish that are used to warm climates. Do not keep them in the water below 60 F (16 C). With that said, guppies can survive if the temperature drops down and are not meant to live in cold water.

Guppies can survive in water temperatures below the optimal temperature range of 72°F-82°F for more than 48 hours. But your guppies will be at risk of hypothermia.

Hypothermia is a health condition that occurs due to cold water temperatures. It means extremely cold. Guppies are tropical fish. If you let them have hypothermia for too long, they will die.

What happens if the guppies in the tank are too cold?


It would be best if you never kept guppies in a tank that is too cold, as that can lead to many problems. Cold water will reduce their activity level, thereby creating more problems. One of the biggest problems with cold tanks is that they will have issues spawning or even stop generating altogether.

The feeling of guppies in a cold tank is similar to how you would feel if you were out in the winter without a coat, hat or gloves. Guppies need warmer temperatures to survive, so being in a cold tank puts them at greater risk of disease. Some diseases they are susceptible to can kill them.

Now that you know how guppies will feel in a cold tank, you will better understand why they need a specific temperature range. Guppies can swim to warmer waters when the water temperature drops. They can't do that in an aquarium, so you must keep their temperature ideal.

When to order a heater for a coloured aquarium?

Unless you live in a tropical environment, having a heater in your aquarium is essential. Guppies are native to the Amazon, where temperatures never drop below 73℉. They cannot survive in the cold temperatures inhabited by humans in North America and the United Kingdom.

It would help to have a heater to make your guppies feel at home. If you do not keep them warm enough, they will be at risk of many diseases. They also benefit from light during the day for at least 8 hours. This is especially important if you grow plants in a guppies tank.

Keep guppies in an outside pond

Guppies love pond water and can do very well in it, especially if you live in a tropical climate. If the pond water doesn't drop below 68℉ during the coldest part of the year, it's a safe place for your guppies to live. However, if it's colder than that, you can still release them into the pond according to specific guidelines.

If the temperature is colder than that, your guppies can only go outdoors during warmer seasons. In most climates, you can leave your guppies outside from late spring through the summer. Although the temperature in the air may drop at night, the sun still heats the water during the day to keep it warm. However, you must return the guppies to indoor temperature when fall arrives.

Most aquariums have hanging heaters. But bright lights also contribute to the amount of heat the water receives. So factoring in hanging lamps and fireplaces is essential. Please ensure that the water temperature is neither higher than the maximum temperature nor below the minimum temperature.

What to do if the water becomes too cold?

Your aquarium will need a heater to control the temperature and the right size heater for your tank. Always keep a thermometer in the aquarium to monitor the temperature range. If the temperature in your guppies starts to drop below 74℉, you need to take action to keep your guppies from getting sick.

If your heater has the correct wattage for your tank size, it may need to be heating the water more. These are ideal heaters for each tank size: 25 Watts for 5 gallons (20L); 50 W for 10 gallons (40L); 100 W for 20 gallons (80L); …

With the suitable capacity, you'll be sure your guppies have the proper water temperature. A controlled temperature is key to keeping your guppies happy and healthy.

What to do if the water becomes too hot?

Summer heat can be unfriendly sometimes, and if the temperature in your home is too hot, chances are your aquarium will warm up a few degrees. If the water is too hot, your guppies may be unable to breathe. You'll want to fix this situation as soon as you notice it.

When the water starts to get higher than 82℉, it's time to act. If you already have the heating and cooling under control in your home, turn on the air conditioning to keep things cooler inside. Cover all windows with blinds to prevent direct sunlight from entering the tank.

Another way to cool the water is to place some ice packs on top and let them freeze. You don't want the fish to go into heat shock by making things too cold, so don't add ice cubes directly to the water. Choose only floating ice packs.

Is cooling the water of guppies dangerous?

When you change the water temperature for your guppies, it's essential to do it slowly. Rapid temperature changes can do more harm than good to the fish. To keep things as safe as possible, you should only change the water temperature by 2℉ every 8 - 10 hours.

This is why monitoring the temperature in your aquarium is so important, especially when the temperature starts to change. If you're not prepared for a heatwave, your guppies could suffer.

Put the Guppy’s tank next to the radiator

We do not recommend placing your guppies next to a radiator. While this will keep them warm in winter, it poses a threat due to the constantly changing temperatures. Guppies don't respond well to constant temperature changes, so they can get sick if their water temperature increases.

To keep guppies happy and healthy, they need to be in a warm environment, and the temperature must be stable. If the guppy's water needs to increase by 3 degrees, it must happen slowly.

The temperature in your home

While keeping your guppies in the suitable range is important, ensuring the correct temperature is even more important.

Some people have mistakenly turned off the heater while away for a few days. They thought everything would be fine; they only discovered their guppies did not adapt to temperature changes when they returned home. While you can reduce the temperature when you must be away for a few days, you shouldn't turn off the heater in the winter.

How many guppies can fit in a tank?


The appropriate number of guppies for a tank depends on the water in the tank. Too many guppies in the tank can affect the water quality and increase the water's temperature.

On average, guppies grow from half an inch to over 2 inches. However, all of this will depend on how large they are. Many people find that a 5-gallon tank only has room for 3 or 4 guppies.

What kind of water do guppies like?

While we know the preferred temperature range, it is also helpful to know what type of water the guppies live in. Guppies do better in hard water, with a pH between 6.8 and 7.8. This makes it easier for many people because your local tap water has a balanced pH of 7.6. It is the perfect balance for guppies to thrive.

Does changing the water of guppies affect the temperature?

It is important to keep the water clean for guppies so they don't swim in their waste. However, if your guppies swim upside down, it could be a sign of something. Find out what it means now!

You'll want to do this carefully as you won't be able to guarantee the clean water you add to the tank will be the same temperature as the water you take out.

We recommend changing only 30% of the water at a time to keep your guppy's water temperature stable. Do this once a week to keep things clean for the fish. A small change at a time will help you keep the water clean without disrupting the guppies.

Since tap water contains chlorine, we recommend pouring the water 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 and not affect the guppies' water. The water will also warm to room temperature during this time, making it safer to add water.


Guppies are versatile fish with many ecological benefits, restoring balance to the ecosystem. Guppies eat malaria larvae. They eat eggs and larvae of mosquitoes, so the number of mosquitoes is significantly reduced to help prevent the dengue epidemic.

These fish are well-suited for their friendly personalities, and they won't disturb the other fish in your community tank. Hey, if you are worried about reproductive problems in guppies, or tips to help guppies reproduce quickly, read the article “How to tell if a guppy is pregnant” HERE.

Now you know quite a bit about the temperature in the guppies tank and how to handle when the temperature of the aquarium changes. Now is the time to choose for yourself a beautiful guppies aquarium. Contact us to buy healthy and active Guppy for your tank HERE. 

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