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?

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 live with other fish. As well as their extremely friendly temperament.

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. 

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.

Do Your Guppies Need A Heater?

Because guppies need a temperatures between 74-82F I’d HIGHLY recommend using a heater in their tank. This way you can ensure that it’s always going to be the right temperature, and you don’t need to worry about fluctuations.

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

  • Increased Metabolism and Activity: When a guppy’s tank water gets too hot, its metabolism speeds up, leading to hyperactivity. This extra movement increases stress, which is a significant health threat to all fish.
  • Stress and Immunity: The increased stress from constant movement weakens the guppy’s immune system, making them more susceptible to diseases and parasites, even from short-term exposure to temperature fluctuations.
  • Oxygen Depletion: Hot water holds less oxygen. If the water becomes too hot, there might not be enough oxygen, making it harder for your guppies to breathe.
  • Ammonia and Beneficial Bacteria: Beneficial bacteria in the tank require oxygen to break down ammonia. High temperatures can deprive these bacteria of oxygen, causing ammonia to build up, which can harm the guppies by burning their gills.

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

  • Reduced Activity and Breeding Issues: Keeping guppies in a tank that’s too cold decreases their activity levels and can lead to significant breeding problems, including a complete halt in reproduction.
  • Increased Disease Risk: Cold water puts guppies at a higher risk of catching diseases, some of which can be fatal, as they will become weaker and weaker due to the poor conditions.
  • Extreme Discomfort: Guppies in cold water experience discomfort similar to a person being outside in winter without proper clothing; it’s harsh and potentially harmful.
  • Wild vs. Aquarium Temperature: In the wild, guppies can move to warmer waters when temperatures drop. However, in an aquarium, they rely entirely on you to maintain their water within the ideal temperature range for their well-being.

Can You Keep Guppies In A 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 68F 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 keep them in a pond with certain conditions.

If the temperature does drop below 68F, then you’ll need to keep your guppies inside until it increases again. 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 and 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.

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 74F, 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.

  • Reducing Heat Sources: Turn off aquarium and room lights, as they contribute to heat. Keeping the area dark helps lower the temperature until the water cools down sufficiently.
  • Remove The Lid: Remove the tank lid to allow heat to escape, but be cautious with fish that jump or if you have pets like cats that might be curious about the open tank.
  • Use A Fan: Set up a fan to blow cool air over the top of the tank, positioning it on a chair or stool if necessary, to help cool the water more quickly.
  • Floating Ice Packs: Place floating ice packs on the water surface to gradually reduce the temperature without shocking the fish. Avoid using direct ice cubes as they can cause a sudden temperature drop.
  • Top Up With Cold Water: Lastly you can remove some of the water from the tank and replace it with cold water to help cool it down.
  • Move It Away From Windows: Remember sunlight can heat aquariums up quite quickly. Especially smaller ones. So make sure you’re keeping the tank away from sunlight as best you can.

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 A Radiator?

I definitely wouldn’t recommend keeping a guppies tank near a radiator. The constant fluctuation of it turning on and off will be extremely harmful to your fish, especially if you have no other way of heating the tank.

Will Changing The Guppy’s Water Effect The Temperature?

Changing the water in your tank will definitely affect the temperature if you haven’t matched it. I normally try and get the new water im adding as close to the tanks water as I can. That way if I’m a little bit off, it’s not going to matter.

On top of this, in order to keep the Guppy’s water temperature consistent, I’d only recommend changing 10-20% of the water at a time.


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! I'm Antonio!

Betta fish keeper for over 6 years now! Since owning a betta I've also housed all kinds of tropical fish, and have seen all manner of problems and how to look after them!

If you need any advice you can always message me or better yet join the Facebook group where a community can answer your questions!