A Complete Guide To Adding Duckweed To Your Aquarium

Last Updated on 2023-08-08

Common duckweed found in aquariums is the same tiny plant that floats on the water’s surface in the wild. It has been included in aquariums for both aesthetic purposes and nutrient control. Despite these plants’ impressive nutrient uptake capabilities, their rapid growth has frequently exhausted available resources.

The leaves and stem of most plants are fused together to create a flattened ovoid shape, and the attached root typically takes the form of fine hairs. When they float on the surface of a body of water, they create the appearance of a vast mat of lush greenery. On occasion, they could be confused with algae. They can be introduced to your aquarium and grown on a large scale.

It’s important to weigh the benefits and drawbacks before deciding to add them to your aquarium, and this article should help you do just that.

Table of Contents

How to Put Duckweed in Your Aquarium

Duckweed is a type of aquatic plant that grows in lakes and often spreads out to cover the surface like a green blanket. It is simple to cultivate, serves as a natural food source for a wide variety of animals, and prevents mosquitoes from laying their eggs in stagnant water. If you have a freshwater aquarium and want to grow some duckweed, read on for some helpful hints.

You Can Find Duckweed in Pet Stores or Collect It from A Nearby Pond

Gather some water and fill your container. Then grab some duckweed with your hand and put it in your container. Considering how quickly duckweed grows and multiplies, 50-100 pods should be sufficient.

Use Potassium Permanganate to Sanitize the Duckweed

To sterilize the duckweed, you’ll need potassium permanganate. You’ll need to dilute 12 gallons (45 L) of water with 1 teaspoon of potassium permanganate. Duckweed should be soaked in the permanganate solution for around 30 seconds. You may get potassium permanganate from any drug store. It is important to disinfect the duckweed to remove any bacteria or bugs.

Spread the Duckweed out On a Plastic Tray that Is 12 to 14 Inches (30 to 36 Cm) Deep

This will help you make an environment where the duckweed can grow well. Duckweed should be placed in freshwater in the tray. If you have access to pond water, utilize that instead of tap water. Given that duckweeds are, in fact, aquatic plants, you will need to utilize clean water. This is why they only grow in ponds and not in the sea. The duckweed will die if exposed to salt water.

Make Sure the Tray Is in A Spot Where It Gets at Least 10 Hours of Sunlight a Day

If possible, position the tray next to a window that gets at least 10 hours of sunlight daily. Duckweed, like many other plants, does best in full sun. Duckweed needs at least 10 hours of direct sunlight per day to thrive, but if you don’t have access to a window that gets that much light, you can also use fluorescent lights.

After a Week, You Should Replace the Water in The Tray

Remove any damaged duckweed from the tray and check it twice a day. It’s time to change out the tray’s water and put in some clean water again. The duckweed will begin to expand rapidly after around 10 days.

Use a Net to Move the Duckweed to Your Aquarium

It is important to ensure that it will receive ample sunshine before putting the duckweed there. Make sure the aquarium lid has a light source attached if you’re going to be transferring the duckweed to a new home. When properly established in an aquarium, duckweed needs no additional attention.

How to Grow Duckweed in Your Aquarium

Growing duckweed couldn’t be simpler. In other words, it’s the perfect aquatic plant for first-timers. In most cases, the issue is not how to grow it but rather how to prevent its rapid spread. To thrive, duckweed needs a specific environment with factors like light and water depth, just like any other aquatic plant.

Let’s take a look at each one separately.

Water Situations

Although duckweed is a very tough plant, following these steps will help it reach its full growth potential.

  • pH levels: 5.0-9.0 (grows best at a pH range of 6.5 – 7.5)
  • Hardness: 2 – 15 GH, 1 – 12 KH

Flow of Water

It’s important to keep in mind that duckweeds grow best in calm water with little surface agitation. So it won’t probably grow in tanks with strong water flows, generated by powerheads.

When conditions are right, the population of these floating plants can double every three days. In this favorable environment, they can multiply rapidly, living up to the name “water weed.”

The Depth of The Water

Besides being a low-maintenance plant, duckweed is also a fantastic option for aquariums of any size. In spite of the fact that they can thrive in as little as an inch of water, it’s important to note that their rate of development slows considerably in deeper tanks. Therefore, one of the most crucial considerations before purchasing duckweed is the depth of the aquarium. It can develop anywhere from 1 to 20 inches deep, but it spreads more slowly the deeper it goes.

Dimensions of the Tank

Duckweed can be grown in tanks of any size, but due to its rapid growth rate, larger tanks of at least 2 gallons are ideal.

Light Requirements

As houseplants go, duckweed requires minimal care when it comes to lighting. It doesn’t require any special care to grow, and it can thrive under both natural and artificial lighting. Putting up some straightforward LED lighting about 12 to 20 inches above the water’s surface is all that’s needed.

If your duckweed doesn’t have green leaves (which indicates photosynthesis is taking place) or translucent/red leaves, it’s not getting enough light to survive (indicating the absence of light).


The temperature tolerance of common duckweed is high. The ideal temperature range is between 63 and 79 degrees Fahrenheit. Growing duckweed couldn’t be simpler. In other words, it’s the perfect aquatic plant for first-timers. In most cases, the issue is not how to grow it, but rather how to prevent its rapid spread.

To thrive, duckweed needs a specific environment with factors like light and water depth, just like any other aquatic plant. Let’s take a look at each one separately.

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How to Control/Contain Duckweed in Your Aquarium

Duckweed is a colonial plant that thrives in still water. Moreover, it is quite hostile, capable of occupying an entire tank. When duckweed colonies grow to cover the entire water’s surface, they prevent oxygen from reaching the water’s depths, making life difficult for aquatic organisms like fish.

Having duckweeds in your aquarium can be helpful, but if you want to prevent/control duckweed from taking over, the following advice will help.

A Wider Net to Catch the Dispersed Duckweed

If you’re removing duckweed from a tank and some of it escapes your hands, you can easily catch it all by passing a net through the tank.

You should run the net through your aquarium a couple times at the very least. Keep in mind that you merely want to slow the growth of duckweed in your tank and keep some for the benefit of your fish.

Put in Some Fish that Eat Duckweeds

Adding natural predators like goldfish, koi, or grass carp that feed on duckweeds is another great way to control duckweed growth in your aquarium. This method eliminates the need for constant maintenance of big aquariums by preventing the proliferation that causes the problem.

Cut Back on Fish Food

If you have fish that naturally eat duckweed, such as goldfish, koi, or grass carp, you could try giving them less fish food. This will encourage them to eat duckweed. While koi fish will eat duckweed, goldfish are far more partial to it. Don’t forget that in order to cut down on fish waste, you should only use the highest quality fish food when you start feeding your fish again.

Regular Monitoring

If you let these duckweed plants grow wild, they could cause problems down the line. Maintaining manageable duckweed development requires periodic tank inspections. A few duckweeds here and there can really be good for your fish.

If you want to keep duckweed from taking over your aquarium, you’ll need to monitor the water quality every day.

How to Get Rid of Duckweed in Your Aquarium

It’s important to get rid of duckweed before it becomes a major problem. Under ideal lighting conditions, duckweed can multiply by a factor of two every 16 to 48 hours. The growth in your fish tank or pond is nearly visible to the naked eye.

Your fish in the aquarium may suffocate, and your aquatic plants may not be able to produce enough oxygen due to the rapid development. This is because it can cover the water’s surface in less than a week, blocking off sunlight and reducing dissolved oxygen levels.

The following are a variety of methods for removing duckweed plants from your aquarium to avoid such complications.

Prepare for Natural Duckweed Predators by Including

Introducing natural predators is a powerful tool for managing duckweed. Put these killers in areas with duckweed immediately. Add plant-loving fish like goldfish, koi, and grass carp to the tank. Know that these predators might not eliminate all of the duckweed in your tank.

Aerate the Water

These plants require water that is either completely still or moving very slowly in order to thrive. Therefore, aerating the water may be a viable option for addressing your duckweed issue. The use of bubble aeration is an effective method for inhibiting the growth of duckweed plants and ultimately killing them.

Rake the Pool

Raking the bottom of the aquarium will help you get rid of any duckweed plants that have settled there. Raking the leaves together is the first step. Then, start pulling the duckweed plants off the surface of the water. You should next get rid of these plants as thoroughly as possible. Make sure there is no way for them to get any water nearby and start developing. The use of a vacuum to pick up the duckweed plants is an alternative method.

Use Only Safe Chemicals

The growth of duckweed can be stifled by using one of several accessible, non-hazardous herbicides. A wide variety of chemicals are employed in the elimination of duckweeds. Common compounds include fluridone, diquat dibromide, and flumioxazin. Diquat dibromide, a herbicide, is one such chemical that should be handled with caution due to its mild toxicity to freshwater fish.

The Use of A Natural Duckweed Killer

To combat duckweed naturally, a treatment of beneficial bacteria from ponds or aquariums is often used. This treatment works by depleting the water of nutrients, starving the duckweed plants and algae. While helpful, these bacteria are insufficient to eradicate duckweed on their own. Remember that they function best when utilized in the manual clean-out.

Make Use Of A Hand-Held Scoop Net

To remove duckweed from a pond or aquarium, especially if there are fish present, using a hand scoop net may not be the best option. Strong nets can be used for this purpose. Duckweeds, in contrast to algae, will never disappear from the water’s surface. This duckweed can be easily retrieved using a netting method. When cleaning a tank, a hand scoop will always give you more precise control.

Completely Drain and Replace Aquarium Water and Thoroughly Clean All Components

If you have a serious duckweed problem, you must change the water and clean the tank. Shut off the tank filter while you clean if it is pulling duckweed from the water’s surface.

Benefits of Duckweed in Your Aquarium

Most aquarium keepers agree that real plants offer several advantages over fake ones. In this sense, duckweed is not dissimilar, and it, too, has several benefits:

Curbing the Spread of Algae

Algae can quickly become a problem for anyone who maintains an aquarium. It’s not only unsightly, but it can be tough to get rid of.

However, duckweed is a powerful ally in the fight against algae. This is because the plant consumes nutrients that algae depend on for growth, such as nitrogen and phosphates, as it quickly expands throughout the growing season. A blanketing species, it also prevents algae from receiving the sunlight they need to flourish.

Appearance Benefits

When you add duckweed to your aquarium, you’re doing more than just adding some foliage for aesthetics. Due to its blanket-like appearance, duckweed is also useful for hiding unsightly structures. It can be used as a surface cover to conceal pumps and other equipment beneath, and it can also be utilized to conceal plant pots in your aquarium.

Keeping More Water from Evaporating

During hot and bright weather, the water in your aquarium will evaporate much more quickly than it will during cold and wet weather. This can be helped by the presence of duckweed, which acts like a blanket on the water’s surface and blocks part of the sun’s heat. Thus, Duckweed helps keep the water colder and reduces the amount of heat lost through evaporation.

Assessing Water Quality

A lot of people think that Duckweed may be used to check how well your pond or aquarium is doing, however this is still only a theory at this point. The theory goes that the more nutrients in your water, the longer the root will grow. As a result, the water is cleaner and healthier when the Duckweed root is longer.

Cleaning up Water

Duckweed’s ability to engage in bioremediation allows it to take up surplus nitrogen and phosphates. The capture of toxins and smells aids in the management of algae growth.

Bioremediation is a technique used to clean up polluted environments like water, soil, and the ground below. The use of duckweed for bioremediation has the added benefits of being both cost-effective and long-term.

Benefits to Fish

Duckweed has two key advantages for fish and other aquatic animals in your aquarium. Some fish may prefer a shady position, and this structure offers that. Due to the high protein content, fish like Koi, Tilapia, and Goldfish can use it as their primary food source.

Disadvantages of Duckweed in An Aquarium

Unfortunately, many of the advantages of duckweed, such as its ability to absorb nutrients quickly, its rapid growth, and its ability to cast a thick shade, are also the cause of some of the disadvantages. Nonetheless, there are additional challenges, such as clogged machinery.

Find out why hobbyists try to keep this plant as far away as possible from their fish tanks.

Consumption of Nutrients

Duckweed’s rapid uptake of nutrients is great for algae, but it can suffocate other plants that you don’t want to thrive at your expense.

Quick Growth

Duckweed absorbs more nutrients than you need because of how quickly it multiplies. As a result, the tank’s resources will be depleted, a huge amount of space will be taken up, and ammonia levels will rise dramatically. If it covers the entire tank’s surface, the other inhabitants won’t be able to breathe.


It’s true that shade is great for preventing algae growth and giving fish a place to hide, but it can also block light from reaching places that could use it. Because duckweed grows so quickly, it can quickly cover up your tank’s other plants, preventing them from receiving the light they need to thrive. This will kill off some of the inhabitants in your tank.

Equipment Clog

Duckweed has the widespread potential to clog equipment like filters and pumps. It can become entangled in powerheads and intakes if its growth is not closely monitored and controlled by fishkeepers. It will be extremely difficult to get rid of this.

Hard to Control

It is challenging to keep duckweed under control once it has become established. It can be a pain to manage, even with careful monitoring, cutting back, and elimination.

Why Is Duckweed Dying in Your Aquarium?

Although it is common knowledge that duckweeds are tough plants, just like any other type of plant, duckweed can be killed out by a number of environmental variables.

  • Inadequate illumination – Duckweed can only live and flourish if they receive an adequate amount of light; if they do not, they will begin to perish.
  • Deficit of oxygen – Duckweed is susceptible to suffocation and death if the water in the aquarium does not have an enough amount of oxygen in it.
  • High concentrations of nitrates – The presence of excessive nitrates in the water can be poisonous to duckweed and cause the plant’s death.
  • Unnaturally high levels of algal bloom – The duckweed will perish in the aquarium if there is an excessive amount of algae because the algae will compete with the duckweed for light and nutrients, resulting in the duckweed’s death.
  • Fluctuations in temperature – Duckweed thrives in warmer water, but if the temperature in the aquarium shifts too much, it might be fatal for the plant.
  • A low pH level – Duckweed is susceptible to toxicity when the water’s pH level is low, which can lead to their demise.
  • Bad quality of the water – Duckweed is susceptible to damage from dirty or filthy water, which will ultimately result in the plant’s demise.
  • Overcrowding – If there are too many plants in the aquarium, there won’t be enough resources (light, oxygen, etc.) for each plant to survive, which will result in the death of the majority of them or all of them altogether.
  • Fertilizer runoff – A rise in nitrate levels, which are toxic to duckweed, can be brought on by an excessive amount of fertilizer in the water.
  • Diseases and other parasites – It is possible for duckweed to contract parasites or illnesses, either of which could ultimately result in the plant’s demise.


Do Fish Eat Duckweed in An Aquarium?

Duckweed is a staple food for many aquarium fish. This includes goldfish, tilapia, and the common pleco. The addition of these fish, or any others, to your tank is a great strategy to slow its growth and provide a steady supply of food.

How Fast Does Duckweed Grow in An Aquarium?

The best conditions for duckweed growth—nutrient availability, sunlight, and water temperature—allow for a rapid doubling of mass in as little as 16 hours to two days. This rate of growth is unprecedented among higher plants.

Will Algae Kill Duckweed in An Aquarium?

Extreme algal bloom will kill the duckweed in the aquarium because it will outcompete the duckweed for available light and nutrients, eventually killing the duckweed.

How to Keep Duckweed in An Aquarium with A Hob Filter?

Using a pre-filter is one of the most effective and simple methods for preventing duckweed from entering the filtration system. To prevent bigger debris like duckweed from being sucked into the filter, a pre-filter can be placed over the intake.

Will Duckweed Help with Algae Problems in An Aquarium?

When kept in an aquarium, duckweed effectively prevents the spread of algae. It forms a thick blanket of greenery over the water’s surface, shielding the area below from sunlight.

Can You Keep Duckweed in A 10 Gallon Aquarium?

There isn’t an aquarium out there that duckweed can’t make a home in. There aren’t many specific parameters to set because of this. All aquariums, whether they contain fish that prefer acidic, basic, or neutral water, can benefit from having this plant.

Is Duckweed in An Aquarium Good or Bad?

As long as their numbers are kept low and under control, they could be good for your aquarium. As a plant that both consumes and releases oxygen, duckweed can be a useful addition to any aquarium.

Does Duckweed Produce Oxygen in An Aquarium?

Due to its ability to purify the air and produce its own oxygen, duckweed is a valuable addition to any fish tank. In this way, harmful chemicals won’t be able to accumulate in your tank, and your fish will have cleaner water to swim in.


The real cost of growing duckweed is how quickly it grows and forms mats. Given that its development may be contained by careful planning, this plant is unfairly maligned. Once you figure out how to keep duckweed from getting out of hand, it can be a really cool plant to have in your own aquariums. It offers a wide range of ecological services that can help you maintain healthy water quality in your aquarium and provide for its residents’ basic needs. Not only that, but it is easy to get and definitely cheap to grow.

If you think this plant will be beneficial for your aquarium, it’s important to learn about the various natural methods available for limiting its growth.

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