Guppies are the most common fish aquarists love to add to their aquarium. They will thrive when kept in an appropriate water condition.
Knowing and fulfilling all the needs of guppy fish is essential to make them live comfortably and grow beautifully.
So, Does guppy need a heater? What is the right heater wattage for my aquarium?. Let us find out.
Guppies do need a heater. The heater keeps the water temperature ideal and stable for your guppies. Guppy fish prefer to live in warm water temperatures between 72-82 °F and will be prone to diseases and parasites if kept in cold and unstable water temperatures.
We will discuss the right heater wattage required according to the size of your aquarium in this article. Also, we will discuss the effects of too hot, cold, and unstable water temperature on our guppy fish.

Contents
- 1 Do guppy fish need a heater?
- 2 Which is the right size wattage heater for my aquarium?
- 3 Which heater is best for my guppies tank?
- 4 Where should I place the heater in my guppies aquarium?
- 5 Guppy fish ideal water temperature.
- 6 Effects of guppies living in too cold water.
- 7 Effects of guppies living in too hot water.
- 8 How the unstable water temperature effects guppy fish?
- 9 What we can do to keep a stable water temperature of our guppies tank?
- 10 Conclusion:
Do guppy fish need a heater?
Guppy fish do require a heater.
Guppy fish thrive in a water temperature between 72-82 °F.
The heater also helps us to keep the stable water temperature of our guppy fish aquarium.
Unstable water temperature can result in life-threatening conditions for your guppy fish.
With adequate water temperature, stable water temperature also plays an equal role in keeping your guppy fish comfortable and away from diseases and parasites.
Unstable water temperature makes your guppy fish come under stress, and they will be vulnerable to various diseases.
Also read: Can Guppy Live In Cold Water?
Which is the right size wattage heater for my aquarium?
Aquarium Size | Required Heater Wattage |
---|---|
5 Gallon /20 Liter | 25 W |
10 Gallon / 40 Liter | 50 W |
20 Gallon / 80 Liter | 100 W |
25 Gallon / 95 Liter | 125 W |
40 Gallon / 150 Liter | 200 W |
50 Gallon / 190 Liter | 250 W |
65 Gallon / 250 Liter | 2 X 200 W |
75 Gallon / 285 Liter | 2 X 300 W |
Which heater is best for my guppies tank?
The right heater for your guppy fish depends on the size of your guppies tank.
Aquarium Size | Recommended Heater |
---|---|
5 Gallon | 25W (FREESEA 25W Heater) |
10 Gallon | 50W (Fluval M50 Submersible Heater) |
20 Gallon | 100W (Fluval M100 Submersible Heater) |
25 Gallon | 125W (EHEIM 125W Heater) |
40 Gallon | 200W (Fluval M200 Submersible Heater) |
50 Gallon | 250W (EHEIM 250W Heater) |
65 Gallon | 2X200W (Fluval M200 Submersible Heater) |
75 Gallon | 2x300W (Fluval E300 Advanced Electronic Heater) |
Where should I place the heater in my guppies aquarium?
You should place a heater close to a filter.
Placing the heater close to a filter will ensure to circulate the warm water all around your guppy’s aquarium.
Not placing the heater closer to the filter will keep one side of the aquarium only warmer.
This will result in guppy swimming on one side of the aquarium.
So, the best place to place the heater is closer to the filter as it will distribute the temperature all around the aquarium.
Also, consider adding one more heater if you have a large aquarium.
When you are placing one more heater, consider putting it opposite the first heater.
Placing your second heater opposite a first heater will make sure to keep the water temperature the same all around the aquarium.
Guppy fish ideal water temperature.
Particulars | Guppy Fish Requirement |
---|---|
Water temperature | 72-82 °F |
Water pH level | 6.8-7.8 |
Guppy fish require a water temperature between 72-82 °F to live comfortably and happily.
Make sure to provide a water pH level between 6.8 and 7.8 to make your guppies thrive.
Also read: Best pH Level For Guppies.
Effects of guppies living in too cold water.
Guppies living in too cold water will become lethargic and will be least interested in moving.
Your guppy will lose its immune system over time and be vulnerable to various diseases and parasites.
Diseases like fin rot, dropsy, and swim bladder disorder will be a common issue for your guppies living in too cold water.
Guppies cannot live in too hot or too cold water as both conditions can be life-threatening for your guppy fish.
It is typically hard to warm your guppy’s aquarium water than to cool it.
However, the best way to keep your guppy’s aquarium water warm and stable is to add a heater.
You can put warm water to maintain the temperature in case the water is too cold (Do it occasionally).
You can keep the aquarium near a warm place, like placing the aquarium near the heater.
However, with all these alternatives, adding a heater to your guppy’s aquarium is the best way to keep your guppy’s aquarium water warm.
Effects of guppies living in too hot water.
Guppies living in too hot water can also be a life-threatening condition for your guppies.
Hot water loses oxygen, making it hard for your guppies to breathe, and they will suffocate.
Also, when there is no oxygen in water, the beneficial bacteria gets unable to eliminate ammonia from the aquarium as they need oxygen to do that.
Ammonia spike in your guppies aquarium will burn the gills of your guppies.
Living in too hot water makes your guppies active or superactive, resulting in issues.
More active guppies will swim erratically and will come under stress.
Your guppies will lose their immune system, and the chances of getting ill will increase.
It is easy to cool the water; you can do these things to cool your guppy’s aquarium water:
- You can use a frozen water bottle to cool your guppy’s aquarium water.
- Reduce artificial and natural lights.
- Keep your guppies aquarium in a cool place inside your home (In a room with an air conditioner).
Also read: Can Guppy Survive In Muddy Water?
How the unstable water temperature effects guppy fish?
The issue of unstable water temperature arises when we perform a water change in our guppies aquarium.
However, there too can be an issue of unstable water temperature if we are not using a heater.
The heater helps us to keep a stable water temperature in our guppies aquarium.
Unstable water temperature can affect your guppies in numerous ways:
- Shock because of sudden temperature change.
- Your guppy will come under stress.
- Your guppy will be prone to various diseases and parasites.
- Guppy will start losing its beautiful colors.
- Your guppy will be less interested in breeding.
Unstable water temperature can result in life-threatening conditions for your guppies.
Guppies will come into shock because of a sudden major change in water temperature.
Usually, this happens when we perform a water change, but it can also occur if you have nothing to maintain the water temperature stable like a heater.
Unstable water temperature will make your guppy come under stress because of a sudden temperature change.
Your guppy can suffer from respiratory problems when the water temperature rises and will find it hard to breathe as hot water will lose oxygen.
Unfavorable water conditions and unstable water parameters will make your guppies lethargic and avoid eating, making them prone to various diseases and parasites.
Your guppy will start losing its beautiful colors because of fluctuating water temperatures.
Unstable water temperature will also affect your guppy’s breeding, as guppies need favorable and stable water parameters to feel comfortable and breed.
Your guppies can also pass away because of unstable water temperature.
Also read: Can Guppy Fish Live In Tap Water?
What we can do to keep a stable water temperature of our guppies tank?
Adding a heater to your guppies aquarium is the best way to ensure the stable water temperature of your guppies aquarium.
Adding a heater will also help you keep the water warm, and your guppies will live comfortably.
Also, consider adding a digital thermometer to your guppies aquarium to keep a regular check on water temperature.
By adding a thermometer, you can keep a regular check on water temperature and immediately take action if there is anything wrong with the water temperature of your guppies aquarium.

Also read: Guppy Fish Minimum Water Temperature.
Conclusion:
Guppy fish need a heater.
The heater not only helps in keeping the water temperature warm but also maintains a stable water temperature.
Unstable and unfavorable water temperatures can make your guppy suffer from a critical condition.
Inappropriate water temperature will make your guppy fish come under stress, and they will be prone to various diseases and parasites.
Consider adding two heaters if you have a large tank.
Reference: ResearchGate, NCBI,