What Fish Species Eat Duckweed?

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Duckweed can make a beautiful addition to an aquarium or a pond. It serves as a nice, all-natural decoration, and has some potential benefits. However, nothing great comes without drawbacks.

Perhaps the biggest problem most people are complaining about is the quick proliferation of duckweed. What starts as a nice aquascaping experiment can turn into a big maintenance nightmare.

If this plant spreads and covers the entire water surface, this can pose a threat to the fish living in the aquarium or pond. Luckily, there’s a very easy solution to fix this issue. In this article, I’m going to teach you about the best fish species to add to your aquarium to keep duckweed in check.

Keep reading to learn more about this pesky little plant, its benefits, and how to deal with it in the most effective way possible!

Is Duckweed Bad for Ponds and Aquariums?

Duckweed isn’t purely bad or good. It brings considerable benefits, but there are also some drawbacks. Duckweed is the smallest and fastest-growing flowering plant in the world. It grows in still or slow-moving waters such as lakes, ponds, and even aquariums.

You’ll often see it floating right on the surface or just below surface water level. Given how quickly this plant grows and spreads, most people treat it like any regular weed to be eliminated. However, duckweed is a high-protein, nutrient-rich plant that makes a great potential snack for certain fish species.

Besides, duckweed acts like any other aquarium plant. It neutralizes harmful compounds like nitrates and helps keep the water clean by filtering part of the waste left behind by fish. It also soaks up nutrients from the soil and water and starves off algae, reducing their growth.

In itself, duckweed doesn’t pose a threat to fish. But due to its quick proliferation, it can form thick blankets that cover the entire water surface. This will impede water oxygenation and will block the light from reaching other plants below the surface.

5 Fish That Loves Eating Duckweed

Duckweed is a nutrition powerhouse. It contains a decent quantity of protein, trace minerals, pro-vitamin A, B vitamins, vitamin K, essential fatty acids, antioxidants, and pigments like xanthophyll and carotene.

It’s safe to consume for most fish species, but that doesn’t mean all fish will voluntarily eat it. Still, certain species love this plant and inhale it at any chance. So, if you’re dealing with duckweed overgrowth, these fish can help you keep this little bastard in check.

– Goldfish

In the wild, Goldfish live in slow-moving bodies of water. They’re naturally exposed to duckweed so you can say it’s part of their natural diet. It’s no surprise then that goldfish love eating duckweed. They’ll binge on it any chance they get. If you have a large group of goldfish in a regular-sized aquarium, your duckweed might be gone quicker than you’d imagine.

The nutrients in duckweed are obviously going to keep your goldfish strong and healthy, but let’s not forget about the plant pigments. The carotene in duckweed is especially good for goldfish because it helps them produce the vibrant orange color we love so much about them.

– Koi Carp

Koi Carp is another species that’s fond of slow-moving and still waters, so it’s safe to assume they’re accustomed to plants such as duckweed. It can do very well in ponds and would make a great addition for duckweed pest control. This species is omnivorous and not a picky eater at all. It will have a bite of anything it can find, including plants, algae, seeds, worms, and other insects.

But one of their favorite food sources is, you guessed it, duckweed! Koi Carp will flock up to duckweed like it’s an all-you-can-eat gourmet buffet. If you’re not careful, you might run out of duckweed before their next mealtime comes. To say that Koi fish could eat their bodyweight in duckweed is probably not an overstatement.

These guys don’t know the meaning of the word “moderation”. Of course, duckweed shouldn’t make up the majority of your Koi Carps’ diet, because they also need other food sources to meet all their nutrient needs. But as a snack or nutritious supplement to their diet, duckweed is really good for them.

– African Cichlids

There’s nothing purer in this world than African Cichlids’ love for duckweed. These fish species would probably inhale duckweed like a vacuum if they could. And because duckweed grows so quickly, you got something to keep them busy.

African Cichlids are very aggressive and competitive over resources like food. They also have big appetites and will feed 3-5 times a day. Having a stable supply of tasty duckweed can keep their violent tendencies in check. There should be enough to go around for everyone!

Of course, duckweed should be treated more like a snack, not a meal replacement. You still have to feed your Cichlids their regular diet of flakes, pellets, and live food.

– Tilapia

In the wild, Tilapia fish live in turbid waters like lakes and ponds, but they can also inhabit shallow streams, rivers, and brackish waters. If you have a pond, rest assured that this species would make a very nice addition to it while also keeping duckweed from overgrowing.

What makes Tilapia different from the other species we’ve discussed so far is that they’re completely herbivorous. As a result, they don’t need anything else other than fresh plant matter. They like eating algae, plankton, and floating aquatic plants like water lettuce and duckweed.

They will eat this little plant up like candy, and they’ll also meet all their nutritional needs. Their digestive system is perfectly adapted to extract as much nutrition as possible from plant foods.

Thus, they’ll get all their protein, vitamins, and minerals from the green leaves that they eat. The only problem you might have in this scenario is that you’ll eventually run out of duckweed to feed your fish.

– Catfish

It’s probably unexpected, but Catfish also like snacking on duckweed when the plant is available. However, this will mostly depend on the catfish species in question. Some catfish are strict carnivores, but most species in this group are omnivorous.

This means they can feed on both plants and animals, typically smaller fish, mollusks, and other bottom-dwelling creatures. Most Catfish species kept as pets can subsist just fine on a largely plant-focused diet as long as they get enough protein and micronutrients.

In fact, most Catfish feeds are plant-based, although they’re made from poor quality ingredients like soybean, cottonseed, and wheat by-products. With such a boring diet, it’s no surprise that Catfish enjoy some fresh, crispy greens like duckweed every once in a while. This plant will also provide Catfish with a nutritious punch that they need to sustain their growth.

Is Duckweed Good for Fish?

By now, it’s pretty clear that the answer is a resounding yes! Most fish love eating duckweed. Some species aren’t as enthusiastic about it, but they can still nibble on these greens for a snack.

Duckweed makes a terrific source of minerals like magnesium, potassium, iron, and calcium, as well as other micronutrients including B-vitamins, vitamin K, and vitamin A analogs. Duckweed also contains a decent amount of protein and it’s full of plant pigments that keep fish looking vibrant and colorful.

The only potential danger of duckweed is its extreme proliferation. This plant grows at an insane rate, and it can quickly cover the entire water surface. This not only means that the duckweed will impede oxygen exchange, but the plant will also consume most of the oxygen and minerals in the water.

If the water doesn’t get properly aerated, your fish will slowly suffocate. But this is a problem only if the plant is left to grow out of control. If you keep some of the fish species that we went over, this will never be an issue. These fish will feast on the little leaves before the plant has any time to take over.

Do Guppies Eat Duckweed?

Guppies like duckweed, so it isn’t uncommon to see them nibbling on some leaves. However, they don’t have a huge appetite for this plant, unlike other fish species. Guppies are omnivorous, and they prefer eating a balanced diet that includes both animal and plant foods.

If they had to choose between high-quality pellets and duckweed, they’d probably eat the pellets first. But you can still feed your guppies duckweed to help them reap the nutrition benefits.

The best way to help your guppies get more of these goodies in is by making your own fish food. Just blend the duckweed with other foods like shrimp or veggies. Dry the food and crush it to make some flakes small enough for your fish to eat.

Do Turtles Eat Duckweed?

Turtles are generally omnivores, so they can eat basically anything, including duckweed. A turtle’s appetite for duckweed will depend on the species. Not all turtle species like the same things. However, duckweed can still make a good high-protein snack for most turtles.

Duckweed is a non-toxic aquatic plant. So, even if a carnivorous species nibbles on these leaves, there won’t be any harm. If your turtles enjoy feasting on duckweed, there’s no reason to worry. Still, duckweed shouldn’t make up the entire plant portion of their diet.


Duckweed is a small but resilient aquatic plant. It can grow and spread very quickly, and this might pose some issues for your fish tank or pond. You might want to get rid of duckweed because it can impede water oxygenation if it covers the entire water surface.

But for the most part, duckweed has potential benefits, from purifying water to starving off these pesky algae that you have to get rid of constantly. Not to mention that duckweed is non-toxic and highly nutritious.

Most fish will enjoy snacking on this plant. Certain species, like Goldfish, Tilapia, Cichlids, and Koi fish will gorge themselves on this green little bastard like there’s no tomorrow. If you ever have to keep duckweed overgrowth in check, these species can help you with that.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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