How To Get Rid Of Duckweed In An Aquarium

Having an aquarium at home is like having a slice of nature right in our living space. It creates a peaceful and mesmerizing atmosphere that captivates us.

But, let’s be honest, it’s not always easy to keep everything in balance. Sometimes, unwanted guests like duckweed can come in and cause trouble. Duckweed might look harmless, but it multiplies so fast that it can quickly take over your whole aquarium.

In this guide, I’ll show you how to get rid of duckweed in an aquarium. I’ll explore how fast it grows and share effective methods to get rid of it.

Plus, I’ll suggest some fantastic alternative plants that can keep your aquarium looking beautiful and healthy. So, let’s get started on this underwater adventure together.

Things to Know About Duckweed

Before we start talking about how to get rid of duckweed, let’s take a moment to understand what duckweed is all about. Duckweed is a type of tiny plant that lives in water, and it’s part of the Lemnaceae family. It has these small, round leaves that stick together and form a thick mat on the water’s surface.

Now, here’s the interesting part – duckweed actually helps to absorb nutrients from the water naturally. But if there’s too much of it growing in your aquarium, it can become a problem. The excessive growth of duckweed can mess up the balance in your aquarium’s ecosystem. 

It may sound strange, but when there’s too much duckweed, it can limit the oxygen supply for other aquatic creatures living in the tank. And that can slow down their growth and overall well-being. So, while duckweed has some good qualities, it’s all about finding the right balance and keeping it in check.

What is the growth rate of duckweed in an aquarium?

Duckweed is quite the little troublemaker when it comes to multiplying. It’s known for its lightning-fast reproduction rate. When the conditions are just right, this sneaky plant can double its population in only a few days. 

This rapid growth can catch aquarium enthusiasts off guard, and suddenly, they find themselves dealing with a duckweed invasion. What’s even more challenging is that duckweed is incredibly adaptable. 

It can thrive in different water conditions, whether the water is still or gently moving. This resilience makes it a real challenge to handle and get rid of. With the right approach and some patience, you can take on this tenacious opponent and restore harmony in your aquarium.

Steps To Get Rid Of Duckweed In An Aquarium

duckweed in aquarium
Image Credit:

Step 1: Use your hands to remove excess duckweed

To start getting rid of duckweed, you can simply use your hands. Yup, it’s that easy. Carefully reach into the water and pick up as much duckweed as you can find. Scoop up those little floating bunches gently, making sure not to disturb the other plants or the fish in your aquarium. 

We want to keep everyone happy and comfortable while we say bye-bye to the duckweed. Just take your time and be gentle while doing this. It’s like tidying up your tank and making it a cozy home for your aquatic buddies.

Step 2: Use a net to collect scattered duckweed.

Now, let’s tackle those little pieces of duckweed that might have broken apart while you were removing them by hand. Grab a fine mesh net, like the kind you use for fishing, and carefully scoop up those scattered duckweed fragments. 

This will stop them from spreading any further in your aquarium. It’s like giving those tiny bits a one-way ticket out of your tank! Using the net helps to make sure we’ve cleaned up all the duckweed and prevents it from coming back. So, keep that net handy, and let’s make sure those pesky fragments don’t stand a chance.

Step 3: Transfer your fish to a separate tank temporarily

let’s take things up a notch for a super thorough cleaning. To do this, you’ll want to move your fish to a different tank with fresh, clean water.

Think of it as a little vacation for your fishy pals. By doing this, you’ll have full access to every nook and cranny of your aquarium without causing any stress to your aquatic friends. 

We want to make sure they’re happy and relaxed while we work on making their home squeaky clean. So, find a nice, comfy spot for your fish to stay temporarily, and then you can get to work on the deep clean without any worries. It’s like a spa day for your fish and a chance for you to give your aquarium some extra love and care.

Step 4: Clean the Aquarium Equipment and Accessories

Time to give your aquarium equipment and accessories some attention. First, you’ll want to take out all the stuff in your aquarium – things like filters, decorations, and any accessories you have in there. Oh, and don’t forget to remove the substrate, which is like the bed of your tank where all the plants grow. 

Once everything is out, give them a good rinse. We want to make sure there are no leftover bits of duckweed or any of its sneaky spores hanging around. This way, we can stop any chances of those pesky plants coming back for another visit.

Cleaning your aquarium equipment and accessories is like giving them a spa treatment, making sure they’re squeaky clean and ready to go back into the tank.

Step 5: Introduce fish that eat duckweed

There are certain types of fish that absolutely love to munch on duckweed. Consider adding fish like tilapia, goldfish, or koi to your tank. They’re natural at keeping the duckweed population under control.

It’s like having your very own duckweed cleanup crew. But, hold on! Before you add these helpful fish, make sure they get along well with the other creatures in your aquarium. 

We want a peaceful and friendly community in there, so choose fish that won’t cause any trouble. We’re all about harmony in the underwater world.

So, go ahead and invite these duckweed-eating champs to your tank, and let them work their magic. They’ll keep your aquarium looking clean and tidy, leaving you with more time to enjoy the beauty of your aquatic paradise.

Step 6: Reducing fish food

Let’s talk about how we can manage the food situation for our finned friends. You see, giving our fish too much food can actually cause some trouble in our aquarium.

When fish get more food than they need, it leads to extra nutrients in the water. And guess what? These extra nutrients become like tasty treats for the duckweed, making it grow even faster. We definitely don’t want that.

So, it’s essential to be mindful of how much food we offer to our fish. Feed them just the right amount they can finish in a few minutes. And if you see any leftovers floating around, don’t hesitate to remove them right away. 

Now, here’s a cool trick to get your fish interested in eating the duckweed. If they don’t seem too interested in it at first, try placing the duckweed on the water’s surface where it can naturally float. 

Fish are curious creatures, and they’re more likely to check out this floating green treat. Once they give it a try, they might realize that duckweed is actually quite tasty. Remember, duckweed loves to feast on nutrients like phosphates and nitrates in the water. 

To keep its growth in check, we need to manage these nutrient levels. Regular water changes are an excellent way to flush out some of those excess nutrients. And using a good-quality filtration system will help keep the water clean and balanced.

Step 7: Monitor the tank for the presence of duckweed

Now that you’ve followed the steps to remove the duckweed, it’s essential to keep a close watch on your tank. Check it regularly for any signs of the duckweed trying to come back.

Staying vigilant is crucial because sometimes those sneaky duckweed plants can try to make a comeback. If you spot even a hint of duckweed returning, you can quickly take action to stop it in its tracks.

So, remember to keep an eye on your aquarium and be ready to act if you see any signs of the duckweed returning.

Your attentive care will keep your tank clean and free from unwanted invaders, creating a happy and healthy environment for your aquatic buddies. 

Alternative options for aquatic plants instead of duckweed

When it comes to keeping your aquarium in perfect harmony without dealing with duckweed, you’ve got some fantastic options. Instead of having duckweed, you can go for other aquatic plants like Java Moss, Water Wisteria, or Hornwort.

These plants are not only pretty to look at, but they also do some really helpful things for your aquarium. They work like nature’s little helpers. First, they add beauty to your tank, making it look like a colorful and vibrant underwater world. Who doesn’t love that?

But it doesn’t stop there. They do two essential jobs. One, they help to provide more oxygen in the water, which is like giving your fish a breath of fresh air. It keeps them healthy and happy.

Second, these plants are like tiny cleaners. They absorb extra nutrients in the water, like those pesky phosphates and nitrates that can mess up the balance in your aquarium. By doing this, they prevent any unwanted algae growth and keep your tank sparkling clean.

Advantages of Duckweed

One of the most significant advantages of duckweed is its superpower-like ability to grow really fast. This might sound surprising, but it’s actually beneficial! The rapid growth of duckweed means it can soak up lots of extra nutrients from the water. Think of it as a natural nutrient sponge.

By absorbing these extra nutrients, duckweed helps to keep your aquarium water cleaner and healthier. It’s like having a little water purifier right in your tank.

When there are too many nutrients in the water, it can lead to problems like unwanted algae growth, which can make your aquarium look murky and unappealing. But duckweed comes to the rescue by reducing those nutrients and preventing algae from taking over.

Disadvantages of Duckweed

One of the main issues with duckweed is its rapid and uncontrolled growth. While its fast growth can be an advantage in some ways, it can quickly turn into a problem if not kept in check. Duckweed has a sneaky way of spreading and covering the water’s surface, which can block out sunlight from reaching other plants in your aquarium. 

When that happens, the other aquatic plants might struggle to grow and get enough light to survive. It’s like duckweed is hogging all the sunlight for itself. Not only that, but too much duckweed can also limit the oxygen supply in the water.

You see, when duckweed covers the surface, it creates a barrier that can prevent oxygen from getting into the water. And just like us, fish need oxygen to breathe. So, if there’s not enough oxygen in the water, it can be harmful to your fish and other aquatic creatures.

Another downside is that duckweed can sometimes outcompete other plants in your tank. It’s like a fast-growing, green invader that takes over and doesn’t leave much room for the other plants to thrive. This can disrupt the balance in your aquarium’s ecosystem and cause some of the other plants to struggle.

So, while duckweed does have its advantages in controlling excess nutrients, it’s crucial to keep a close eye on it and prevent it from becoming too much of a good thing. By managing duckweed properly, you can ensure a healthy and harmonious environment for all the inhabitants of your aquarium.


Creating and caring for a stunning aquarium is a labour of love that demands attention and know-how. Understanding how quickly duckweed grows and applying the step-by-step techniques I’ve shared will help you say goodbye to this pesky plant and bring back harmony to your underwater paradise. 

We hope this article has been valuable to you. If you have any questions or need further assistance, please feel free to leave a comment below. Thank you for taking the time to read our guide.


1. Can too much duckweed kill fish?

Answer: Yes, too much duckweed can indeed be harmful to fish. While duckweed helps to control excess nutrients in the water, an excessive amount of it can cover the surface of the aquarium, blocking sunlight and reducing the oxygen supply. 

This can lead to low oxygen levels in the water, which is essential for fish to breathe. If not managed properly, the overgrowth of duckweed can stress and even suffocate the fish, ultimately posing a threat to their health and well-being.

2. Does duckweed take oxygen away from fish?

Answer: Yes, duckweed can affect the oxygen levels in the water if it covers the surface too densely.

Duckweed forms a thick mat on the water’s surface, which can hinder the exchange of gases between the water and the atmosphere. As a result, it may reduce the amount of oxygen entering the water, potentially leading to oxygen depletion. 

Adequate oxygen levels are crucial for the survival of fish and other aquatic creatures. Therefore, it’s essential to monitor the growth of duckweed and ensure it doesn’t overwhelm the surface area, allowing sufficient oxygen for the inhabitants of the aquarium.

3. Does duckweed purify water?

Answer: Yes, duckweed does have a role in purifying water to some extent. It has the ability to absorb extra nutrients like nitrates and phosphates, which helps control algae growth and maintain water quality in the aquarium.

However, it’s important to manage the amount of duckweed carefully. While it can be helpful in controlling nutrients, too much of it can cause problems like low oxygen levels and overshadowing other aquatic plants. 

Regular monitoring and proper management are essential to benefit from duckweed’s purifying properties without harming the aquarium’s ecosystem.

Achieving a balanced aquarium with the right amount of duckweed will create a thriving and harmonious environment for your fish and plants to flourish.

Additional Posts:

  1. How Often To Fertilize Aquarium Plants
  2. Why Are My Aquarium Plants Melting
  3. Do Aquarium Plants Need CO2
  4. How to Plant Pothos in an Aquarium
  5. Which Fish Clean The Aquarium [Nature’s Little Helpers]