Guppy Grass

Jennifer Doll

Jennifer Doll


Guppy Grass

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When picking out the right submerged plants for your private aquarium, there are a few factors you’ll want to consider. Guppy grass will make you and your fish very happy for a lot of reasons. 

Guppy grass, also known as Najas guadalupensis (the scientific name), Water Nymph, or Najas grass, is a popular fast-growing aquatic plant for your fishy friend’s home. The young fish like to hide in it, and the bigger ones like to swim around it. 

Guppy grass grows easily and requires little maintenance. However, there are some standards of care you’ll need to maintain if you’re considering adding this desirable background plant to your fish tank. Keep reading to check out our comprehensive guide on growing and caring for Guppy grass. 

Guppy Grass in Its Natural Habitat

If you’re going to care for Guppy grass in your home aquarium, you should know where it thrives naturally. 

Guppy grass is native to Canada and most of the US but has been introduced to other parts of the world. It’s a freshwater plant found primarily in ponds and streams (both in swift currents and slow) and even water-filled ditches. 

Chances are you’ve seen Guppy grass out in the wild. If you’ve looked at your local waterways, canals, or brooks, it’s probably there, just below the surface. It needs low to medium light to survive, so it’s never too deep. Guppy grass is quite a hardy plant. It proliferates with minimal nutrients, fertilizers, or oxygen. Because of its healthy growth rate, it’s considered an invasive species in some countries. 

Guppy Grass Description

Because of its aforementioned quick and full growth, Guppy grass will make your aquarium appear beautifully lush. The branching stems grow to about 3 centimeters long and 1-2 millimeters wide with a feathery appearance. 

This fast-growing annual aquatic plant has long, flexible leaves that are slightly transparent. Still, it never looks see-through because its uncomplicated growth is so full but appears to range from a rich, light green to a dark green color.

If you look very closely, you may pick out the tiny unicellular teeth on its leaves. Guppy grass also grows tiny flowers near the base of the plant and has white roots. You probably won’t notice them unless your aquarium walls magnify your view. 

Guppy grass makes for a beautiful environment. If all goes well, you’ll have a bright green tank with full growth and with happy fish. 

Benefits of Guppy Grass

The Najas guadalupensis growth rate is very impressive. Guppy grass will grow and propagate with minimal effort on your part. Besides being very easy to grow and maintain, Guppy grass has a lot to offer to your aquarium. 

Plants, in general, are good to add to your aquarium (assuming you use suitable species for the right fish) because they can clean the tank or act as a food source or hiding place for your animals. Fish also like to use clusters of guppy grass when they’re spawning. 

Guppy grass makes your tank look beautiful and cleans it amazingly well. With Guppy grass, you won’t see a lot of algae growth at all. It competes with algae for nutrients, and it will usually win. 

That’s good if you’re a new aquarium owner who may forget to clean the tank. If this is you, we can show you the best practices when it comes to tank cleaning

It can be bad if you own algae-eating fish who may want the algae growth that Guppy grass inhibits. If this is the case, you can still use Guppy grass; simply give your algae eaters algae supplements with their food.

Guppy grass introduces oxygen to your tank like any plant, so it helps maintain a healthy environment for all of your aquatic pets. Your herbivorous and omnivorous fish will also eat Guppy grass. 

Fish also produce carbon dioxide and ammonia, which these fast-growing low-maintenance plants (and other plants) can absorb. It will also remove other toxins and metals. Overall it will help balance your tank’s ecosystem. 

As we mentioned, other plants carry similar benefits. If you want a verdant multi-grass aquarium, look at other popular underwater grasses you can use with or without our Guppy grass. 

Planting Guppy Grass

You’ll be glad to hear that this aquarium plant is among the easiest of grasses to use in your home aquarium. Planting a bunch of Guppy grass is straightforward and can be done in a few different ways. 

You can choose to root in the substrate or leave the grass free-floating. Leaving it free-floating is the easier and more popular way to grow Guppy grass. You simply take your Guppy grass and place it in the tank; it’ll form a nice dense mat of growth from there. 

Guppy grass doesn’t feed off the substrate, so the root system isn’t powerful. That means it may not root to the aquarium floor well. 

However, if you choose to plant in the substrate, it’s not hard, either. You just need to divide the stems, space them evenly, and place them about 2 inches under the substrate. It should then grow normally. 

Remember, switching from floating to rooting can cause Guppy grass to melt. If this happens, don’t panic. You can correct the situation by clearing dead sections and allowing the Guppy grass time to recover. 

If you notice your Guppy grass is melting, a wait-and-see approach is best. It likely just needs time to adapt. Adding a bunch of fertilizer probably won’t help you, and it can cause unwanted excess growth. 

Tank Requirements

As we said, Guppy Grass can thrive in a variety of environments. If you’re going to mimic its ideal conditions, here’s how you should set up your tank:
Best pH: 7 (though the 6-8 range is fine for Naja Grass)

  • Best temperature: 68F-79F (Celsius: 20-26.1)
  • A substrate is unnecessary but can be used
  • Low to medium lighting 
  • Water hardness range can be 5 to 12 dKH
  • Though it can live in fast-moving water, a slow flow is best for this grass and will keep this free-floating plant from clogging your filter.

A Note About Tank Size

The tank size depends more on how many fish you plan on keeping than the Guppy grass. Remember, this grass can grow basically anywhere. 

You could plant it in a micro tank if you wanted to. We don’t recommend that because of how fast it grows. Unless you’re willing to trim continuously, it’ll outgrow any tank under 15 gallons too quickly to be considered an “easy-to-maintain” plant. 

How to Care for Guppy Grass

If you’ve been into aquascaping for a while, you’ve probably seen fertilizing options or used CO2 injections in your tank. The beauty of Guppy grass is that it doesn’t usually require either of these things. 

You may want to use a liquid fertilizer now and then, especially if you notice the plant starting to die off or suddenly stop growing. But overall, Guppy grass will require very little attention. 

Pruning and clipping will be the main things you need to do. As we mentioned in the propagating section, you’ll need a good, sharp set of scissors. 

A dull pair will make your life more complicated and damage your nice plants. You’ll need to make sure you do this correctly since Najas grass can overtake your tank and all its inhabitants if you aren’t careful. 

Like any new addition to your aquarium, you should consider quarantining it before adding it to your tank. Any new living purchase can potentially carry contaminants like parasites or pesticides into your tank. You don’t know for sure what your pet shop used to care for its stock.

After that, place your new Najas plant in your water column, trim occasionally, and watch it flourish. 

Who Should Live with Guppy Grass

Despite the name, it’s not just Guppies that will enjoy living with Guppy grass. There are plenty of suitable tank mates that would be thrilled to have this grass in their environment.

Any small freshwater fish can thrive with Guppy grass. Herbivores can eat it, small fish can hide in it, and others can swim around it. Live-bearing fish especially like it since it provides the ideal spawning shelter.  

Like crayfish, crabs, and shrimps (just about any shrimp), shellfish will live well with Guppy grass. They’ll eat it as well as hide in it. Because it grows so quickly, it’s unlikely your shrimp can over-eat or kill Najas. 

Life as diverse as Goldfish (who enjoy chowing down on Najas grass), Catfish, Tetra, Platies, Rosy Barbs, Plecos, Silver Dollars, and snails will also thrive alongside Najas. 

It’s a very versatile plant and will suit most aquarium environments. Fish that like low lighting will do best with this plant since it also requires low light. 

Potential Guppy Grass Problems

Guppy grass is an ideal plant because it doesn’t come with a lot of problems. The thing you need to watch out for is its fast growth. If you’re not paying attention, it can completely overtake your tank. 

If Guppy grass grows unchecked, it can choke other plants, take up too many nutrients from the water, or block light sources from your fish and other aquarium plants. You can solve these problems with simple trimming. 

To trim your Guppy grass (or any of your aquatic plants), you’re going to want to invest in extremely sharp stainless steel or other rust-proof scissors. 

Using a dull scissor to cut your plants can end up crushing healthy stem tissue- which will inhibit growth. If you use a sharp scissor to cut back your Guppy grass, you won’t have to worry about rot. 

Make sure you clear the cut pieces from the tank. Guppy grass can propagate from just a free-floating cutting. You’ll end up with more undesired growth if you aren’t careful about cleaning the cuttings out of your tank.


You’ll also need to dispose of Guppy grass carefully. We’ve already mentioned that it’s considered an invasive species in some parts of the world. 

Don’t flush it, and douse it with bleach to make sure it’s dead. You can also consider adding the dead plants to your compost or burying them in your yard. 

You don’t want Guppy grass getting into your local waterways, especially if it isn’t native to your area. It can grow unchecked and cause all sorts of problems outside of its natural habitat, including killing off the local wildlife.  

Where You Can Buy Guppy Grass

You’ll be happy to know you can buy this easy and versatile plant pretty much anywhere, for very little money. Guppy grass is a staple of many aquarium setups so that you can find it easily. 

You can get it at just about any local pet store rather than buying it off the internet. Though hardy, Guppy grass doesn’t transport very well because of its sensitivity to environmental changes. 

Look up banned or restricted plants by state or country. Make sure Guppy grass is legal in your area. If you live somewhere Najas grass is considered an invasive species, it may be illegal to order it. 

Before You Go

Guppy grass or Najas grass is a great plant for community tanks and is ideal for beginners and long-time aquarium owners alike. It’s not a picky plant, it’s nearly impossible for a new owner to kill, and it’s a great low-maintenance option. 

Everyone loves how easy it is to care for and how beautiful this almost fluffy green plant looks in your aquascape. It offers nutritional benefits to your fishy community and keeps their home clean. Most freshwater fish that you own will benefit from having it in the tank. 

Other than the potential for overgrowth, you’ll encounter very few problems when caring for Guppy grass. You should make it the next addition (or the very first) to your aquarium today. You’ll love how it looks, and your fish will love living with it. 

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