Guppy Grass Care: The Ultimate Guide

Okay, so here is our statement.

Guppy grass or Najas guadalupensis, is hands down one of the most amazing and versatile plants you can add to any freshwater aquarium. 

There you go, we’ve said it!

Easily found in bodies of water almost worldwide, Guppy grass is everything an aquarium keeper needs to maintain a healthy, thriving aquarium for small species of fish and invertebrates.

It’s amazingly versatile; you can plant it or have it free float. The plant is a beautiful bright green, does wonders for the water quality and fish absolutely love it. Not too bad for a common water plant!

Here’s everything you need to know to introduce and care for guppy grass in your aquarium.

Guppy Grass Overview

If you have ever sat by a lake or pond, you have probably seen guppy grass. It’s an emerald, long grass with very thin, closely spaced leaves. The plant floats in clumps and roots in the bottom. 

Guppy grass is native to the Americas from Canada all the way down through the contiguous United States, Mexico, Central, and South America. It is, literally, everywhere in America. 

The grass has also been introduced to much of the world, including Israel, Japan, Palestine, and the West Indies. 

This probably occurred by guppy grass being flushed down toilets or otherwise disposed of from aquariums. 

This is one of the worst things you can do because guppy grass will grow wherever it is placed, either on purpose or by accident. 

Once it takes root, it takes over and can block all the sunlight into that body of water. Not good! So be careful with how you dispose of guppy grass.

It is very common to slow-moving bodies of water such as streams, ditches, ponds, and lakes. The plant is very temperature tolerant. It survives winters under the ice and year-round warm waters.

Guppy grass is an annual plant. In the wild, guppy grass will die off over the winter and regrow in the spring. It spreads by fronds and branches breaking off and being carried to new places by current, floods and sometimes human intervention.

Why You Need Guppy Grass In Freshwater Aquariums

Guppy grass is amazingly beneficial to every freshwater aquarium. It is so much more than an ornamental plant. It provides the basis for a healthy ecosystem that benefits every species in your aquarium. 

Here is why you should have it in your tank.

Gives Shelter

Guppy grass provides the perfect shelter for the thousands of varieties of small fish available to aquarium keepers. The grass creates niches and hiding places where guppies, tetras, and other species can escape larger, hungry tank mates. 

When added to an aquarium as a rooted plant, clumps of guppy grass provide home bases for different schools or groupings of fish, so they have their own territory and feel safer. 

Small shrimp and invertebrate varieties thrive in it as well. 

They will crawl over the plant and hide along its stems and branches. They also love it for a more important reason.

Vital for Small Fish Breeding

Vegetation is vital for the breeding of most of the small fish species kept in Aquariums. Guppies, mollies, and many others need vegetation for their eggs to attach to, and guppy grass is an ideal plant for this. 

Some species need rooted plants and others floating plants. Guppy grass is ideal for both. For egg-laying and mouthbrooding species, guppy grass provides attached points for fertilized eggs and provides concealment for newly hatched fry. It also provides what every aquarium needs.

Cleans Water

One of the marvels of guppy grass is its ability to filter water. The plant is almost like an aquarium superspecies to filter high levels of ammonia and nitrates from fish waste from the water.

It even helps remove carbon dioxide, industrial pollutants, and toxins that may be in the water. But guppy grass goes one step further.

Increases Water Oxygenation

Guppy grass is very good at pulling carbon dioxide from the water and putting oxygen back in. So good, in fact, it can bolster the efforts of your filtration system and help keep fish healthy longer, in between cleanings. Fresh, oxygenated water is the best. The next benefit is equally important.

Provides Food

If you have species in your aquarium that are omnivores or herbivores, they will appreciate guppy grass. Those fish will nibble at the leaves as part of their diet. Species like Cichlids, Goldfish, Plecos, and Rosy barbs all love to snack on guppy grass. 

Small fish and fry will nibble at the microorganisms that grow on the leaves and stems of guppy grass. These are a naturally occurring part of a healthy aquarium, and a part of the wonderful ecosystem guppy grass helps provide.

But there is one thing that will be in short supply, and you will appreciate it.

Algae Control

Guppy grass can leave the water so clean of pollutants using as a fertilizer that algae has a difficult time growing in the aquarium. 

Aquariums with guppy grass stay much cleaner than tanks with other species of aquatic plants. That reduces the amount of cleaning you have to do and is a win for you, especially in large tanks.

Care for Guppy Grass

Guppy grass is considered the easiest aquatic plant to care for. All you have to do is place it in your aquarium as a floating or rooted plant and keep the water clean. Guppy grass does the rest. Here are the broad parameters you need to maintain your aquarium to keep guppy grass green and thriving.

Aquarium Minimum Sizes

Guppy grass can be placed in any size aquarium, even a 2-gallon desktop size as long as the water is changed frequently. For that reason, the ideal minimum size is 10 gallons with a standard aquarium filtering system.

Guppy grass like water movement, so a water return system that keeps water flowing in the aquarium is important. It does not have to be a high rate of return. Match the water flow to your tank mate’s needs and that will be sufficient for guppy grass.

Guppy grass lends itself well to both horizontal and vertical aquarium formats. It will grow to the limits of available space. There is one thing you do not have to worry about.

Water Temperature Range

Considering the range of guppy grass is from the frozen northern Americas to the tropics of Latin America, and beyond, guppy grass is tolerant of a wide range of temperatures. It grows best and maintains its beautiful emerald green shade in temperature ranges of 50 – 86F (10 – 30C). Set the temperature to match the fish you keep in your aquarium, and guppy grass will do well. 

Water Quality Range

As with water temperature, guppy grass is forgiving of a very wide range of water quality. It will thrive in conditions ideal for all ranges of freshwater aquarium fish. 

If you keep the pH between 6.0 -7.0 and the water hardness anywhere from 2 – 25 your guppy grass will work its magic in your aquarium. Here is how to get it started.

Ideal Substrates

Guppy grass will grow in almost any substrate fine enough to hold roots. This ranges from beach sand to coral sand to natural or colored small gravels. 

Since guppy grass is a floating plant, if you want to root it in the bottom of your aquarium, you will need to use rocks or other weights to hold the plant in your substrate until it has established roots. It will not take more than a few weeks. Guppy grass grows quickly.

Just about the only substrate guppy grass does not do well in are large rocks where its roots cannot gain purchase. If you have this as your substrate, keep guppy grass as a floating plant. That makes it easy for what you need next.

Aquarium Lighting

A brightly lit aquarium that follows a normal day/night cycle is ideal for guppy grass. Light can be artificial or natural. Just provide plenty of it.

Guppy grass that does not get enough light will fade to a sickly yellow. At worst, it will die back and turn into a slimy mess. 


One of the best things about guppy grass is that it is a prolific growing plant. This also presents one of its challenges. Guppy grass can grow so much that it overpowers an aquarium. 

Thinning is the means to keeping your plants under control. Cutting back guppy grass is not difficult. Using a sharp pair of scissors, trim back the plant to your desired size. 

When trimming guppy grass, be sure to net the scraps and small cuttings, so they do not clog your aquarium filters. Dispose of the cuttings and scraps in the trash. Do not flush them down the toilet or throw them in waterways. The plant grows so readily you may be helping to spread guppy grass where it does not belong. Do this with them instead.

Planting and Propagation of Guppy grass

Planting and transplanting guppy grass is a simple and great way for new aquarium keepers to propagate water plants. Here is how to get it done.

Planting new Plants

Guppy grass can be purchased at most tropical fish stores. To plant guppy grass, push the plant down to the substrate and use rocks or another type of weight to hold it down. 

Give it a few weeks and the guppy grass will be rooted. If the tank is well lighted, guppy grass will grow to the top of the water.

Adding guppy grass as a floating plant is even easier. Just place the plant in the water, and it does the rest. 

As a floating plant, guppy grass will grow roots that dangle down and will eventually reach the bottom. These should be periodically trimmed if you want to keep them as floating plants. 

Propagating Existing Plants

Thinning guppy grass presents a great opportunity to propagate the plant to other tanks. Any cutting that has stems, branches, and leaves will grow into a complete plant in any aquarium that has the right water and light conditions. 

When propagating, larger clumps of guppy grass have better chances of thriving. These can be added as floating or rooted plants as you desire.

Fertilization & Maintenance 

In normal aquarium conditions, guppy grass is self-sufficient and does not need any fertilization. The ammonia, carbon dioxide, and nitrogen it absorbs from fish waste, combined with plenty of light, is enough to keep it growing and healthy.

Some aquarium keepers like to fertilize their water plants. In tanks with species that will tolerate some fertilizer in the water, small amounts of fish-friendly liquid fertilizers can be added to help plant growth. Use sparingly and watch for side effects in fish health.


Guppy grass is almost universally compatible with everything you can put in an aquarium. Here are just a few of the fish species that thrive in it:

  • Cardinalfish
  • Celestial Pearl Danio
  • Ember tetra
  • Green Fire Tetra
  • Mystery Snails
  • Neon tetra
  • Otocinclus Catfish
  • Platies
  • Pygmy Cory Catfish

Invertebrates such as shrimp love guppy grass. A few of them that do well in aquariums include:

  • Amano shrimp
  • Bamboo shrimp
  • Blue Bolt shrimp
  • Blue Tiger Shrimp
  • Blue Velvet Shrimp
  • Crystal Red Shrimp
  • Ghost shrimp
  • Malawa shrimp
  • Red Cherry Shrimp
  • Snowball Shrimp
  • Vampire shrimp

Snails love guppy grass. Popular varieties are:

  • Malaysian Trumpet snails
  • Mystery snails
  • Nerite snails
  • Japanese trapdoor snails
  • Ramshorn snails

Guppy Grass Issues

Guppy grass is almost the perfect aquarium plant. It does have a few downsides aquarium owners should keep in mind. 

Rapid Growth 

The good thing about guppy grass is that it grows so fast. The bad thing about guppy grass is that it grows so fast. If you do not keep an eye on it, guppy grass can take over a tank with so much growth that it pushes fish out of cover and turns the tank into a twilight jungle. 

Breaks Easily 

While guppy grass is resilient, it is not durable and can break quite easily. In an aquarium, rough handling by humans or fish can lead to fragmented plants, which can clog filters. 

Tank Shadowing

One of the drawbacks to having guppy grass in an enclosed space is that it can grow to cover the tank’s surface, leaving the rest of the aquarium in the twilight. This is called tank shadowing and can cause all sorts of problems.

Common issues with light shadowing are sluggishness and loss of vibrancy in species that need direct sunlight and reduced water quality. Over time too much guppy grass can cause the plant to die off, leaving a big slimy mess in your aquarium.


If you have only to have one type of aquatic plant in your coldwater aquarium, guppy grass is a great candidate. It is one of the most versatile aquarium plants you can own. 

There are also other types of plants, however…

Guppy grass is so easy to care for. It will help keep your aquarium clean, keep your fish safe and secure, and add vibrant shades of green to your displays. Your fish will thank you.

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