Do Guppies Need a Heater?

Guppies don’t need a heater if you are able to maintain a temperature between 74°F and 82°F. If you are not able to maintain these temperatures, guppies need a heater.

In the rest of this detailed guide we run through (almost) everything you need to know about making sure that the water in your guppy tank is properly heated – but not too much – and why it’s so important!

Do Guppies Need a Heater?

Do guppies really need a heater running 24/7 to maintain water temperatures or is that a bit of overkill for these fish?

Well, though guppies might not “need” a water heater the same way that other tropical fish do – depending on where you live in the type of fish you keep, anyway – it’s always a good idea to have this kind of tech maintaining stable temperatures for your fish all year round.

Guppies are a pretty resilient species of fish, but water fluctuations – particularly extreme fluctuations – can really do a number on their health and wellness.

If you live in a climate where temperatures can swing like crazy (not just from one day to the next, but one season to the next) you definitely want to be sure that a heater is evening things out for you.

Get a heater and keep your guppies happy explanation board

Guppies Swimming in Fish Tank

Breaking Down the Perfect Temp for Keeping Guppies

Your guppies are going to do best when they are in water held between 74°F and 82°F.

Now, there are lots of people out there (especially those that live in colder climates) that think keeping the thermostat over the winter months at 74 is enough to maintain those water temperatures – but nothing uld be further from the truth.

Just because the air temperature in your home is held at 74°F (which is a lot higher than most people keep their home, by the way) doesn’t mean that water temperatures are.

Folks that live in warmer climates that have air conditioning running all the time to keep their homes between 60°F and 70°F aren’t going to be able to keep their guppy tank within the “sweet spot”, either.

On top of all that, you need to remember that water temperatures rise much slower and cool much slower, which is why holding consistent temperatures are a challenge, too.

Invest in a quality water heater that can hit and hold anywhere between 74°F and 82°F and you’ll be good to go.

Water Heater Placement Tips and Tricks

A good tip for heater placement is to tuck it just as close to the filter as possible.

You might not be able to position the heater right on top of the filter, but you really want to scoot it up close. The closer the better.

This positioning means that the heated water gets sucked through the filter right away, helping to circulate the hot water as much as possible. The end result is a gentler, more even heat that keeps your guppies happy but also avoids wild temperature swings that could jeopardize their health.

If you’re working with a larger tank you might even want to go with two (or more) heaters, even. This will avoid one side of the tank being warmer than the other – a problem that could shock your fish, too.

Keep a Constant Eye on Water Temps

Just as important as getting water temperatures into the 74°F to 82°F zone is maintaining a stable temperature at whatever you hit in that “Goldilocks” range.

You don’t want to have your tank water be 74°F one day, 82°F the next, 76°F the day after, and then 80°F the day after that.

No, you want a stable, consistent temperature that your fish can acclimate to and then thrive in.

This is another big reason that having a water heater (even if you keep your home and the aquarium space relatively warm) is such a game changer.

You’ll be able to set your temperature and let the heater handle the heavy lifting of keeping it consistent.

Just be sure that you check your water temperatures at least a handful of times each week.

Whenever you go to feed your guppies is the perfect time to do this checkup. Have a glance, make sure that everything is good to go, and make any necessary adjustments to maintain those stable temperatures.

The Danger of Water Getting Too Cold

Cold water is devastating to a guppy population.

You’ll notice that your guppies become sluggish, that they look fatigued, and that they have a really difficult time moving around the tank and even eating. The stress on their body (as cold-blooded creatures) is incredible.

You need to warm things up if temperatures start to drop below 74°F, and certainly if temperatures start to get around 70°F. That’s the real stress zone.

The Danger of Water Getting Too Hot

Tank water that is too hot will cause just as many problems for your fish, though they will have the opposite reaction initially.

Hot tank water will have your guppies zipping around, darting like crazy, and trying to expand energy that is eating them up.

As the temperature rises, the amount of dissolved oxygen goes down. If it goes down enough, your fish will not get enough oxygen to breathe. Just like humans, if fish don’t get enough oxygen, they will become stressed which dramatically increasing their chances of becoming sick and dying

Add conditioned cool water to the tank to cool things down incrementally, take the lid off the aquarium to let things “air out”, or run a fan across the surface of the water tower to get rid of some of those high temperatures.

Closing Thoughts

At the end of the day, as long as you keep these things in mind – and try to keep water temperatures as even and as consistent between 74°F and 82°F – you won’t have anything to worry about for your guppy population.

They will be happy, they will be healthy. And they will be zipping around in water perfectly suited to their biology!