Do Guppies Need Substrate?

Some fish are particularly picky about the kind of substrate added to their tank.

Guppies don’t necessarily need substrate, but it helps to create most optimal conditions by providing surfaces for beneficial bacteria to grow as well as providing a more natural feel for your guppies.

Below we run through almost everything you need to know about whether or not guppies need substrate, the pros and cons of adding substrate to a guppy tank, and which kind of substrate you should use going forward.

Let’s jump right in!

Do Guppies Need Substrate?

Guppies aren’t going to stage some kind of revolt if a specific kind of substrate hasn’t been added to their tank, but they are going to like to see some kind of substrate for sure.

For starters, guppies are going to use a little bit of substrate to sort of “scratch their belly” when they get itchy.

Sometimes this kind of behavior is spurred by problems with the water in the tank or your fish feeling stressed out. Sometimes, though, guppies just want to bump up against something and give themselves a halfway decent scratch.

Another reason that guppies appreciate substrate (even if they don’t realize it themselves) is because substrate is so important for keeping aquatic plant life happy and healthy, too.

Substrate offers a more resilient foundation for plants in your aquarium to grow and flourish. And that means that you’re going to get better oxygen and better filtration of your water through these plants, too.

A little bit of substrate goes a long way and should be added to every guppy tank.

Close up shot of orange, black, and silver guppy

Advantages of Adding Substrate

There are a lot of advantages for adding substrate to a guppy tank (or any fish tank, for that matter).

Keeps Guppies Happy and Healthy

For starters, guppies just naturally seem a little happier and a little healthier when they are zooming around in a 20 gallon or larger tank that has plenty of substrate on the bottom.

Guppies are active and social fish that like to zip around in a school. They like to probe and explore every square inch of their enclosure, and that means bouncing from the top surface of the water all the way down to the substrate – and everything in between.

Without that substrate your fish would only see the bottom of your glass tank – a bland, barren, empty sort of landscape. Who wants to deal with that?

Helps Support Tank Plants

Substrate gives a rock solid foundation for aquarium plants to grow on, giving them a better opportunity to reach their maximum potential as quickly as possible.

If you are going to fill your tank with aquatic plants (and your guppies will really appreciate that) you need to be sure that you have substrate on the bottom of your enclosure.

Without that substrate your plants are going to be listless. They are going to spend a lot of their energy (and a lot of their precious resources) fighting to find mooring and to survive when they could have spent that time, energy, and resources growing larger and providing better oxygen and filtration to the tank itself.

If you have plants, substrate is required.

Looks Great!

There’s just something about a bit of substrate that adds a little bit of balance to a fish tank that would have been missing if it wasn’t there.

Substrate adds a bit of grounding material to the tank, not just for you but for your guppies as well. It looks a lot more natural, it helps keep stress levels down, and (when you do it right) can add a lot of visual interest to your tank, too.


Not all is sunshine and roses with substrate, though.

That’s why you have to be careful when you add it, making sure that you add the right substrate and that you understand exactly what you are getting into going forward.

Tank Maintenance Gets a Little Harder

Tank maintenance is certainly going to get a little more challenging as soon as substrate materials enter the mix.

Every now and again you are going to have to vacuum out the old substrate and pitch it in the garbage, especially if you want to keep your water fresh and healthy.

Fish waste, old food, and anything else that might have fallen into the tank will inevitably end up burrowing into your substrate. Before you know it your ammonia levels are through the roof and poisoning your guppies.

You might even have to deal with other toxic chemicals building up in your substrate, too.

Removing and replacing substrate is never all that much fun.

Substrate Can Make Water Murky

If you have any “scavenger fish” stuck in the tank with your guppies they are probably going to swish and swirl around the substrate every now and again, kicking up clouds of muck and dust that (hopefully) settles eventually – but clouds your tank in the meantime.

This is almost always a temporary problem but it is a problem all the same.

What Kind of Substrate for a Guppy Tank?

Though there are a lot of different substrate options to pick and choose from, two of them separate themselves from the rest of the pack when you are thinking about adding material to a guppy tank.


Gravel is a fantastic substrate when you want to be sure that your material stays on the bottom of the tank (doesn’t get sucked into the filter).

Because gravel is so heavy it’s going to go right down to the bottom and stay there. It isn’t going to be kicked up, swished around, or cloud your tank water the way that other materials might.

On top of that, you don’t have to worry about harmful bacteria building up in gravel quite as much as you would have with other materials. Water can flow freely throughout each individual piece of gravel (for the most part) making sure that bacteria get sucked into the filter and out of the water.

You will, however, have larger food particles and fish waste get stuck in gravel more often than not. This means your ammonia and other toxic chemical levels will rise and have to be addressed.


Sand works well as a substrate for guppies, creating a very natural looking environment for these fish to enjoy without taking up a ton of space in the tank, too.

Most of the time you don’t have to worry about bits of food or fish waste getting stuck in sand, either. These kinds of things are going to weasel their way into the cracks and crevices of sand like they would with gravel, slowly poisoning water over time.

On the flipside, though, sand is very light and can get kicked up by scavenger fish that route through it. You might end up with some of that sand getting sucked into your filter and potentially compromising its effectiveness.

Combine all of that with the fact that sand substrates are often much more challenging to clean than gravel (and almost always need to be replaced completely when the time comes) and it may or may not be an option for you.