What is the Maximum Temperature for Guppies?

As tropical fish, guppies naturally enjoy warmer waters than most aquarium fishes are accustomed to. Colder waters will affect your guppies in several ways, disrupting their reproductive behavior and causing fish sickness, among other things.

The other extreme isn’t better either, since excessively warm waters will cause a whole new set of problems.

Just as guppies have a minimum water temperature limit, they also have a maximum one. Guppies thrive in balanced and steady environments, where the water temperature remains pretty much the same year-round.

Temperature fluctuations, especially more significant ones, will cause guppies a lot of problems, primarily a weakened immune system.

This will leave them vulnerable to bacteria and parasites, aside from causing them a lot of physiological stress.

What is the Maximum Water Temperature for Guppies?

Ideally, the water’s temperature should revolve around 74 – 82 degrees F. Guppies can even manage 68 F and will struggle at 64-62. Anything below that will cause serious health issues and even death. But, while most fish owners are well aware of the dangers of cold water, few acknowledge the threat posed by hot waters.

That’s because it’s easier for the water to naturally cool off than to heat up. Except, maybe, when the heater malfunctions and increases the water temperature without you realizing it. This isn’t necessarily a reason to worry, so long as the water temperature doesn’t go over 92 F. Guppies can withstand this temperature, but only for short periods of time.

But what happens when the water does reach 92 F or goes beyond it? Several things can happen here:

  • Guppies will suffocate – The hotter the water, the lower the oxygen level it can hold. If the water reaches or exceeds 92 F, the oxygen level will significantly diminish, causing your guppies breathing problems. Anything higher than could potentially kill your guppies via suffocation.
  • Ammonia build-up – The water tank holds a variety of cultures of beneficial bacteria. These cultures accumulate on the tank’s bed, around the plants, and on the tank’s walls. Their role is to prevent ammonia build-up, keep the water clean, and provide your guppies with a safe and healthy living environment. The problem is that these bacteria need a consistent oxygen level to survive. Warmer waters will hold less oxygen, killing the beneficial bacteria as a result and depriving the tank of these useful organisms. This will increase the levels of ammonia, causing your guppies to experience a swift and painful death.
  • Immune problems – These generally occur whenever there are any extreme temperature changes, including recurrent fluctuations. Too cold or too hot waters will cause your guppies to experience a weaker immune system, making them prone to infections and parasites. A lower immune system will also stress your fish, causing erratic swimming, aggressive behavior, and lower appetite.

In other words, any drastic changes in the water’s temperature will affect your guppies and even potentially kill them.

Do Guppies Require a Heater?

You will find a lot of information on this issue and a lot of conflicting answers. It’s well-known that guppies require a filter system and an air pump, like most aquarium fishes. But I would argue that they also need a heater, no matter the region you’re living in or the room’s temperature.

The most widespread argument is that guppies only need a heater if you live in colder areas where it is more likely for the room temperature to fluctuate. Tropical areas will provide a naturally warmer habitat, making the heater unnecessary.

I think that’s false and that the heater is always necessary, no matter where you live. This is because temperature fluctuations are always a thing, no matter whether you live in a tropical area or not. There’s also the aspect of home insulation.

If your home is insulated and you live in a warmer area, the inside of your home will be colder. This can drop the inside temperature below 70, which isn’t ideal.

It’s also worth mentioning that guppy fry are even more sensitive to temperature changes. They prefer warmer waters than adults, with little-to-no temperature fluctuations as possible.

A water heater is perfect for preventing temperature fluctuations and keeping the water within the optimal parameters. I suggest getting a fitting water heater to keep your guppies safe and comfortable throughout the day, no matter how the air temperature changes in your room.

There’s also a critical aspect to mention here, one that few fish owners are aware of. The aquarium water will stay at a lower temperature than the room. So, you might think that you’re warm while your guppies sit in dangerously cold water, which may impact their comfort and health.

A high-end heater that you can rely on will eliminate these risks.

The Perfect Water Temperature for Your Guppies

The ideal water temperature for your guppies sits at around 74-82 degrees F. Anything below or above that puts your guppies at risk of developing health problems.

A reliable heater will allow you to monitor the water temperature so you can adjust it whenever necessary. If you can’t afford a heater or don’t want to buy one, I suggest avoiding getting guppies to begin with. Several other fish species thrive in colder waters than the guppies, including golden barbs, Rosy barb, bloodfin tetra, weather loach, etc.

The Best Fish for Warm Water

If you’ve decided that guppies are too much trouble, you can always opt for warm water fish species. Some of the most popular species include:

– Betta Fish

This gorgeous fish is the perfect choice if you wish to add color and style to your tank. The males, in particular, show fluffy fins and a sky-blue body that will attract all eyes. This species uses its pectoral fins to swim since their long and rich tails are only for show.

As a result, you will see the Betta fish floating more than swimming, which is natural for the species.

– Swordtail

The swordtail has a unique look, with its prolonged tail edge, reminding of a sword. This species comes with a lot of color variety and a prolific reproductive rate. If you plan on getting a swordtail family, make sure to limit the number of males. Otherwise, you will have a lot of little surprises swimming around your tank.

And you’ll not even see them coming since swordtails are livebearers. You will need to carefully monitor the females to prevent overcrowding.

– GloFish

The GloFish is the most exquisite creature that you can have in your tank. Think of little neon fishes glowing in a rainbow-lit aquarium, and you’ll get the picture. These are genetically modified creatures that display fluorescent pigmentation, perfect for vivid aquariums.

Since these fishes come in a variety of colors, you should also get several of them. I recommend using LED lights to really make those colors shine and add a vibrant and vivid feel to your aquarium. Don’t worry, they’re small, so they won’t overcrowd the tank. Plus, they are friendly, energetic, and constantly on the move and will coexist with other fish species with ease.

– Neon Tetra

The Neon Tetra is another small and cute aquarium fish coming with vibrant daytime colors that fade during nighttime. The Neon Tetra has a neon blue body with a red stripe towards the tail. Their distinctive look will add positive energy to your aquarium and a drop of vibrant color.

– Bushy Nose Plecostomus

This species of Plecostomous can thrive in tropical aquariums with warm waters. It is the ideal choice for those looking for something unique-looking to diversify their aquarium life. This yellow and long fish has beautiful, transparent fins and prominent eyes, giving it a distinct look.

Some aquarium species also have thick whiskers, making them look like they have alligator mouths.


As tropical fish, guppies love warm waters. That’s not to say that they have no limits. Just like their comfort suffers as the water temperature drops below a certain threshold, they also experience health issues when the temperature increases too much. I recommend keeping the water temperature in the 74-80 F range to prevent any unwanted surprises.

This is ideal for both adult guppies and fry during their developmental phase. If you still have questions about the water temperature, feeding, or anything related to guppies, comment below, and answers will come.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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