Guppy Grass (Najas Guadalupensis): Care Guide

Common Name(s)Guppy grass, Najas grass, Water nymph
Scientific NameNajas Guadalupensis
OriginNorth America
Ease of GrowingEasy
Height3 feet
Temperature50-86°F (10-30°C)
Growth RateVery fast
PropagationCutting stem
Light RequirementLow to medium
CO2 RequirementNot required
Guppy Grass
Guppy Grass (Najas Guadalupensis). Tony Rodd, CC BY 2.0

What is Guppy Grass?

Guppy grass is a fast-growing plant that is relatively easy to take care of. There are a lot of benefits to adding them to your aquarium as well. Caring for guppy grass is easy, but there are a few things to consider when planting it.

Guppy grass (Najas Guadalupensis) is native to North America, and guppy grass is a tall plant that grows fully submerged in freshwater, with long stalks and thin leaves extending from each branch.

It’s found in many places, including streams, ditches, ponds, and waterways. Its fast growth rate and aggressive expansion earn it an invasive species status in some countries.

Guppy Grass Care

Guppy grass care comes down to a few factors: light, temperature, and pH. Let’s take a closer look at each factor in more detail.

Light Requirement

This plant is fairly versatile, but you should be aware of a few guidelines for aquarium lighting.

Guppy grass does well in medium to low light in a tank; if exposed to high light, you risk the plant getting a reddish tint in its leaves. While this might seem attractive visually, be aware if your plant does start to change to this color, it is not thriving, and you should consider reducing the light exposure.

Ideally, guppy grass should be exposed to light for approximately 8 to 12 hours daily. Aside from a reddish-brown tint, if it is exposed to extremely high light conditions, you also risk burning the plant.


Guppy grass is fairly versatile with temperature and can withstand a wide range of temperatures. This makes it easy to blend into your tank with other plants that may have more specific temperature requirements.

Guppy grass can thrive in temperatures ranging from 50 degrees Fahrenheit to 86 degrees Fahrenheit, making it one of the more versatile plants used in aquascaping.

pH Levels

The last main factor to consider for your plant’s care is the pH level of your tank’s water.

Guppy grass thrives best in a pH level between 6.0 and 7.0, but you can get slightly outside of these ranges with minimal impact on the plant.

This range is in line with many other plants used in aquascaping, so it’s likely that this factor will fall in line with other plants in your tank already.

Growth Rate

One of the most distinct characteristics of guppy grass is its incredibly fast growth rate. Guppy grass is an extremely fast-growing plant, so much so that it earns the status of invasive species in a few countries.

On one hand, this is a good thing for those new to aquascaping. You’ll be able to grow this plant fast which is satisfying compared to other slow-growth aquatic plants.

On the other, it grows so fast that it can risk overrunning your tank. When growing guppy grass, you’ll want a plan to manage the plant and keep it at bay.

There are two easy ways to manage the growth of your guppy grass. One is by getting fish that will consume the grass as it grows. This obviously has two benefits, first that it will keep your plant under control, and second, it provides food for your fish to munch on.

The second method is to trim it by hand. While this isn’t providing food for your fish, you can use your trimmings to propagate your guppy grass, which is essentially a free plant for you to use or give to a friend.

Guppy Grass Height

While we’ve mentioned that guppy grass can grow fast, we haven’t discussed the size of the plant.

Guppy grass is one of the taller plants used in aquascaping, with a height of approximately 3 feet when fully mature. The leaves on the plant are narrow, thin, and up to 3 centimeters long.

Is Guppy Grass Easy to Grow?

In general, guppy grass is an aquarium plant that is relatively easy to grow.

As mentioned, the three main factors for guppy grass care are light, pH, and water temperature; once you’ve ensured all of these are balanced, your grass is almost sure to thrive. All three of these factors are important, but they do fall within the normal ranges of many other aquatic plants. This makes guppy grass easy to grow in a tank with other plants.

A fertilizer is not needed for this plant. However, if you’re concerned about the health of your guppy grass, you can add fertilizer. This will help guppy grass that is in less-than-ideal conditions or in a tank that might be lacking nutrients in the water.

If you do choose to use a fertilizer, it’s recommended to use a liquid one. This type of fertilizer is easier for Guppy Grass and other aquatic plants to absorb and reap the benefits.

How to Grow Guppy Grass & Propagate

How to Grow Guppy Grass in an Aquarium

Let’s talk briefly about the best ways to use guppy grass in an aquascape.

You have multiple options to incorporate guppy grass into your aquascape, meaning you can either plant it or let it float in your tank.

Guppy grass has a characteristic called heterophylly, which means that depending on if you plant it or let it float, it will change the shape of the leaves on the plant.

How to use Guppy Grass for an Aquascape

While you can grow guppy grass planted or floating, one method is easier than the other.

Growing floating guppy grass is somewhat easier than growing planted guppy grass because you risk your plant breaking apart when planted.

Because of how long and thin guppy grass is when rooted to a substrate, the plant can become a little fragile. This does not mean it’s impossible to grow plants, but it can be a little trickier than floating.

Floating guppy grass can pose a separate potential issue, though. Because of the fast-growing and expansive nature of the plant, it can risk blocking light from the rest of your tank. This factor is easy to manage, though through regular trimming either by hand or via fish in your tank eating the guppy grass.

Can You Create a Guppy Grass Carpet?

Guppy grass, while it has many other benefits and pros to using it in an aquascape, is not a good plant to create a carpet.

Essentially, this is because of the plant’s fast and aggressive growth rate. It grows too out of control to create a carpet. If this is a goal for your aquascape, we recommend choosing another plant.

Benefits of Growing Guppy Grass

There are many benefits of growing guppy grass. Let’s cover a few in more detail.

Reduces Algae Growth

Guppy grass is a great plant to consume all excess nutrients in your tank. If you’re new to aquascaping, this may not sound like a benefit, but it is.

Because guppy grass consumes the excess nutrients in a tank, it reduces and prevents algae growth, which is a problem that can plague many aquascapes.

Fish Love It

One benefit we’ve briefly touched on is that guppy grass is something your fish will love. Certain types of fish, like goldfish, silver dollars, and cichlids, will consume guppy grass. This is useful as it’s food for them and helps trim the plant back to maintain it in your tank.

While some types of fish like to snack on guppy grass, others like to hide in it and swim around the many stalks of guppy grass. When it naturally occurs, fish often hide in guppy grass weeds to gain protection from predators.

Balances Nutrients and Removes Toxins from Your Tank

Guppy grass also has some added benefits that contribute to water quality in your tank and the balance of nutrients and toxins.

Guppy grass, like some other aquatic plants, produces oxygen that will benefit your entire tank; additionally, it removes materials like heavy metals, toxins, ammonia, and nitrates from the water as well.

Aesthetically Pleasing

Aside from all of the other benefits covered earlier in this article, Guppy Grass is aesthetically pleasing.

Many who enjoy aquascaping choose to add guppy grass because of its beauty and how it looks with the other plants and fish in their tank.

Is Guppy Grass Right for Your Tank?

Guppy grass care is fairly easy, and if you’re experienced in aquascaping you’ll likely have no trouble growing this plant. As long as the main factors of light, water temperature, and pH level are maintained, your guppy grass will likely thrive.

However, there are other considerations that might make this plant not the right choice for your aquarium. The main consideration is how aggressively guppy grass grows. If you do not have fish that will trim your plant and are not interested in hand trimming regularly, you could have issues with the plant taking over your aquarium.

Leave a Comment

Your email address will not be published. Required fields are marked *