Guppies are tropical fish, which means that in in wild they live in warm water. They can withstand and tolerate a wide range of water temperatures. But, really what is the minimum water temperature for guppies?
The minimum water temperature for guppies is 72 °F (22 °C). For a short period of time, 1-2 days, guppies can support as low as 65°F (18 °C) water temperature, but the chances of developing diseases are very high. Offering your guppies a stable water temperature is the best way to keep your fish healthy.
In the following, I will give you few tips on how to control the water temperature and how to keep it stable.
Do Guppies Need a Heater?
As mentioned above, guppies need warmer water. If you live in a climate where the outdoor temperature drops under 68 °F (20 °C) in the winter, most likely you will need an aquarium heater.
In the winter, most of us keep a stable 70-72 °F (21-22 °C) in-door temperature. In theory, this could be enough to heat up the water of your aquarium.
However, this air temperature can’t provide a stable heat source for your guppy fish tank. The water heats up slower than air, so is the air temperature is 70 °F (21 °C), the aquarium water temperature will be lower.
So, you will need to heat the water of your guppy aquarium. I highly recommend checking out my other article on how to choose the heater size for your water volume.
Also, if you don’t have a heater yet, I recommend using the Eheim Jager from Amazon, which is a reliable and high-quality heater. I use these heaters for years and still work extremely well.
Temperature When Doing Water Changes
When doing water changes, it is important to pay attention to the temperature of the water you are putting into your guppy aquarium.
You need to adjust the temperature of the fresh water to be as close as possible to the water temperature in the aquarium.
If your aquarium has a water temperature of 73 °F (23 °C), the fresh water should have a temperature between 70-77 °F (21-25 °C). Add the fresh water slowly, so the guppies can adapt to the new water temperature and parameters.
To measure the temperature of the water you are adding, you can use a digital water thermometer. I use this one from Amazon. It is a cheap and reliable device to measure water temperature on the go.
Warm or Cool Water Temperature?
As I wrote above, guppies can tolerate a range of water temperatures. Now, a few questions may arise. Should you keep your water temperature on the cooler or warmer side? Which is the best water temperature for guppies?
You can keep guppies in water with temperatures between 72-82 °F (22-28 °C).
If you want to grow your guppies faster, you should opt of the warmer water temperature. However, if you are keeping guppies for fun, you can go for the cooler water.
In cooler water, guppies will live longer, while in warmer water guppies will have a shorter life span, but will grow much faster.
Keeping guppies in a stable water temperature is the key to having healthy fish. Water temperature is important for guppies and you should not go below the minimum recommended water temperature: 72 °F (22 °C). However, you should also pay attention to other water parameters such as pH level, GH level, ammonia level, nitrite level, and nitrate level.
To measure water parameters, you can use the API 5 in 1 test kit from Amazon.
You can raise beautiful and healthy guppies by feeding a healthy diet, doing regular water changes, and keeping your fish in stable water parameters.
Questions & Answers
I really disagree with this article. Maybe your strain of guppies is not good, in our club, they are perfectly healthy in our pound in the summer, with no heating, and no filter (only natural filters), and they go back in their indoor tank only in fall. No heating at home neither. Guppies can be kept at 18°C all the day, with no changes in their behaviour, and they even live longer than in warmer temp.
Thanks for your comment! You can totally disagree with me, and I respect your opinion.
Guppies indeed can live in cooler water, and this is what I’ve stated in the article. I’ve also mentioned that in cooler water they will live longer, while in warmer water they will grow faster, but have a shorter lifespan.
I’ve been running some tests this year and will share the results in a separate article, when the tests are finished. I can tell you that guppies will survive even in cooler water. For a short amount of time guppies will survive in 15 °C (59 °F) water temperature. Though, my goal is to provide the conditions for my fish in which they thrive. I found that keeping them in 22 °C (72 °F) water is best. In this water temperature they will grow pretty fast, they will produce a lot of fry and develop amazing colors.
My guppies water temperature gets up to almost 90 every day and I still see at least 12 of the original 17 fry. They are 5-9 weeks old and enormous. Guppies can tolerate pretty high water temp.
Yes, guppies can tolerate even 90 °F (32 °C). The problem is not the higher temperature, but the oxygen level. As water temperature increases oxygen level in water decreases. Above 86 °F (30 °C) the oxygen level can be critical for fish and they can deplete dissolved oxygen really quickly. If the water surface is large, then the oxygen exchange could be enough even at higher temperatures. With a low water surface and high water surface, you should be worried about oxygen levels.
Also, guppies can tolerate really low temperatures. I’ve tested it, and they can survive even in 55 °F (13 °C) temperature water. Though their colors will fade and will become less active.
Fabian, Thank you. I appreciate the efforts you’ve put in here.