Frogbit vs Duckweed: The Ultimate Guide for Aquarists

Floating plants like frogbit and duckweed are popular choices for aquariums and ponds. They provide shade, absorb excess nutrients, oxygenate the water, and give fish and invertebrates places to hide and rest. But what are the key differences between these two plants? This comprehensive guide examines everything you need about frogbit and duckweed to decide which is better for your freshwater environment.

Frogbit vs Duckweed

What is Frogbit?

Frogbit (Limnobium spp.) is a small floating plant member of the Hydrocharitaceae family. It is native to South America but has spread to other tropical and subtropical regions. Other common names for frogbit include spongeplant, South America frogbit, and Amazon frogbit.


There are a few different varieties of frogbit available:

  • American frogbit (Limnobium spongia) is the most common type used in aquariums. It has round or heart-shaped leaves that resemble lily pads. Leaves are typically 1-2 inches wide.
  • Giant frogbit (Limnobium laevigatum) – As the name suggests, this variety has much larger leaves than American frogbit, typically 3-4 inches wide. It also has slightly more textured leaves.
  • Brazilian frogbit (Limnobium brasiliense) – This species has slender, pointed leaves about 1 inch wide. It is the smallest frogbit variety.

Frogbit plants, no matter the type, feature clusters of long, dangling roots beneath their floating leaves. These feathery roots provide surface area for beneficial bacteria to grow.

Frogbit Care

Caring for frogbit is quite simple since it is a low-maintenance floating plant. Here are some tips for keeping it healthy in your aquarium:

  • Lighting – Moderate lighting is ideal for frogbit. Low light will cause slow growth while high light encourages algae. Aim for 2-4 watts per gallon of full spectrum or 6500K lighting.
  • Temperature – Frogbit grows best in warm water between 70-82°F. Cooler temps below 65°F may cause dieback.
  • A neutral pH around 7.0 is preferred, but frogbit tolerates pH between 6.0-8.0.
  • Water movement – Minimal water disturbance allows frogbit to spread across the surface. Avoid strong currents.
  • Fertilizer – Use liquid ferts or root tabs for other plants. Frogbit gets most nutrients from the water column.
  • Pruning – Trim off any yellowing or deteriorating leaves. Thin plants by scooping out excess to prevent overcrowding.

With its adaptable nature, frogbit can thrive in almost any freshwater aquarium when given the basics for growth.

Frogbit Growth Rate

One of the benefits of frogbit is its fast growth rate under good conditions. The plant spreads rapidly via its runners and offshoots. Here is what you can expect:

  • Frogbit typically doubles in size every 2-3 weeks.
  • Growth rate increases in warm, brightly lit tanks with added CO2 and fertilization.
  • Frogbit can cover the entire water surface in 1-2 months, starting with just a few plants.
  • Regular pruning prevents it from completely taking over the tank. Remove excess plants weekly.

The quick growth allows frogbit to soak up excess nutrients like nitrogen and phosphorus. This helps reduce algae growth. But left unchecked, you’ll soon have an aquatic jungle!

Frogbit Flower

When grown emersed or allowed to overcrowd, frogbit may produce delicate white or light purple flowers. These resemble small lily flowers and add a pop of color above the green leaves. The bloom time is usually mid to late summer. Flowers are short-lived, lasting just 1-2 days before fading. They feature three rounded petals and a yellow center. Though pretty, the flowers are not crucial to frogbit’s growth and rarely appear underwater.

Is Frogbit Good for Fish?

Frogbit offers several benefits for aquarium fish:

  • Shade – The floating leaves provide shaded areas for fish to retreat from strong light. Many species appreciate and utilize darker spots.
  • Oxygenation – Frogbit releases oxygen into the water column during photosynthesis while absorbing carbon dioxide. This improves dissolved oxygen for fish.
  • Hiding Places – The dangling roots create the perfect hiding and spawning spots for shy fish. Fry can also shelter there safely.
  • Nutrient Absorption – As mentioned, frogbit soaks up excess nitrates, phosphates, and other pollutants, creating cleaner, healthier water.

By offering cover, improving oxygenation, and reducing algae-fueling nutrients, frogbit creates a more natural habitat for fish. Most species will not eat the leaves. The long roots do not usually obstruct swimming areas either.

Amazon Frogbit vs Duckweed

Amazon frogbit is often compared to duckweed as they are similar small, floating aquarium plants. A quick rundown of differences:

  • Leaves: Amazon frogbit has round leaves vs duckweed’s oval leaves.
  • Size: Frogbit leaves get up to 2″ wide while duckweed leaves are 1⁄4-1⁄2″ wide.
  • Roots: Frogbit has trailing roots and duckweed does not.
  • Growth: Frogbit is slower and easier to control than duckweed.
  • Appearance: Frogbit looks more like a miniature lily pad vs duckweed’s pinhead size.

While both can work for aquariums, frogbit is larger, slower growing, and more ornamental. Duckweed is better for very small tanks and ponds.

What is Duckweed?

Duckweed (Lemna minor) is a tiny, green freshwater plant floating in stagnant or slow-moving waterbodies throughout North America. It is the smallest flowering plant known at just 1-5 mm in size. You may know it as water lens or bayroot.

Duckweed belongs to the Araceae family along with larger aquatic plants like Anubias. It reproduces rapidly through budding, allowing duckweed colonies to double within 1-2 days under ideal conditions. The plant has no stems or true leaves but rather small, flat, oval-shaped thalli. A single root hair dangles underneath to absorb nutrients.

There are over 40 duckweed species, but Lemna minor is most common. They can be green, yellow, or red hued. Their rapid spread is why duckweed is sometimes considered an invasive weed in ponds and lakes. However, when controlled, duckweed has advantages that make it a staple floating plant for aquarists.


Duckweed Aquarium

While duckweed may be a nuisance outdoors, it has some benefits for aquarium keepers:

  • Fast growth allows duckweed to quickly soak up excess nitrates, phosphates, ammonia, and CO2.
  • Provides shade and cover for fry and small fish at the water’s surface
  • Offers spawning and hiding spots for shy fish species
  • Improves oxygen levels through photosynthesis
  • Gives fish fry and small invertebrates additional food source options

To use duckweed successfully in a home aquarium, start with just a small handful in a balanced, established tank. Allow it to multiply into a complete carpet. Scoop out excess plants weekly and avoid overfeeding to control growth. With routine maintenance, duckweed can be a useful floating plant.

Duckweed Growth

One reason duckweed spreads rapidly is its ability to reproduce asexually. A single plant can produce 10-20 daughters per week. Warm, nutrient-rich water fuels exponential growth. Here’s how it spreads:

  • The mother plant develops buds that detach and become new plants, repeating the process.
  • With no natural competitors, duckweed quickly coats the water’s surface.
  • Colonies can double in size every 1-2 days.
  • Excess fertilizer (nitrogen and phosphorus) accelerates growth.
  • Stagnant water encourages faster spreading than flowing water.
  • Duckweed tends to grow faster than other floating plants like frogbit.

While duckweed provides benefits, its fast growth can quickly get out of control without routine thinning. The speedy multiplication is more suitable for ponds and large tanks.

Is Duckweed Good for Aquariums?

Used in moderation, duckweed can be beneficial to aquarium ecosystems:

  • As it rapidly spreads, duckweed absorbs ammonia, nitrates, phosphates and CO2 that would otherwise fuel nuisance algae.
  • The small size allows it to cover the entire surface, shading out algae and stabilizing pH fluctuations.
  • Fish like bettas and gouramis appreciate resting spots under the thick duckweed mat.
  • Duckweed removes odors from the water, keeping the tank smelling fresh.
  • The small plant is a natural food source for many fish and invertebrates.

The key is preventing duckweed from completely overrunning the tank. With regular thinning and pruning to allow light penetration, duckweed can be an asset for aquariums. Otherwise, its fast, unchecked growth will create problems.

Duckweed for Sale

Getting starters is easy and affordable if you want to try duckweed in your aquarium. Here are some options:

  • Local pet stores often sell portions in their plant section for just a few dollars.
  • Online retailers offer deals for bulk duckweed starter bundles shipped right to your door. Look for portions with at least 50-100 plants.
  • Other aquarists frequently sell clippings via forums, Facebook groups, and sites like AquaSwap. You may even be able to get some for free.
  • Duckweed is abundant in still bodies of water worldwide. Collecting a starter portion from a local pond yourself is another option.

No matter which source you use, isolate and rinse duckweed thoroughly before adding it to your tank to avoid pest issues. Start slowly and thin it regularly to keep it in check.

Why is Duckweed Called Duckweed?

Duckweeds get their common name from their symbiotic relationship with waterfowl in the wild. Ducks, geese, and swans all forage extensively on these tiny floating plants as a food source. Their droppings provide fertilizer that fuels duckweed growth, creating a mutually beneficial connection.

Duckweed’s oval shape and small size are reminiscent of a duck’s footprint on the water’s surface, further reinforcing the name. The plants naturally accumulate on the protected banks where ducks feed on insects, creating large floating mats.

Waterfowl nibble on the tender leaves, roots, and stems of duckweed. The plant provides protein, minerals, and other nutrients for the birds. Watching a duck scoop up mouthfuls of duckweed makes it easy to see why the plant earned its moniker.

Comparing Frogbit and Duckweed

Now that you know the basics of frogbit and duckweed, let’s compare their advantages and disadvantages for aquariums. This head-to-head breakdown will help determine the better choice for your setup.

Frogbit vs Duckweed Size

The most obvious difference between these plants is their size. Duckweed is minuscule at just 1/16” – 1/4″ per thallus. Frogbit leaves reach 2” wide, much larger than tiny duckweed.

The duckweed’s small size makes it suitable for nano aquariums as young as 1 gallon. Frogbit needs at least a 10 gallon tank to have space between leaves. Both plants spread rapidly across the surface, but frogbit leaves more open swimming room underneath.

Frogbit vs Duckweed Reddit Opinions

Aquarium forums like Reddit contain extensive debates on frogbit versus duckweed. Here are some of the key points community members make:

  • Duckweed is better for nano tanks – Tiny leaves fit well in small aquariums that can’t accommodate larger frogbit.
  • Frogbit is more aesthetically pleasing – Its round leaves and trailing roots look more like a natural lily pad vs duckweed’s specks.
  • Duckweed is harder to control – It grows and spreads more rapidly than frogbit, quickly taking over the tank.
  • Thin frequently for both plants – Prune excess growth every 1-2 weeks before it gets out of hand.

Reddit users emphasize being diligent with pruning and maintenance no matter which plant you choose to prevent them from becoming a nuisance.

Difference Between Frogbit and Duckweed

Here is a quick rundown of the major differences between these popular floating plants:

  • Leaf shape – Frogbit has round, coin-like leaves. Duckweed leaves are tiny and oval-shaped.
  • Leaf size – Frogbit leaves reach 1-2” wide while duckweed leaves are just 1/16” – 1/4”.
  • Roots – Frogbit has delicate, trailing roots and duckweed has a single short root hair.
  • Growth speed – Duckweed spreads faster, sometimes doubling daily vs. frogbit’s slower expansion.
  • Appearance – Frogbit looks more ornamental while duckweed is more utilitarian.
  • Tank size – Duckweed suits small tanks under 5 gallons. Frogbit needs mid-sized tanks of 10+ gallons.

Both are useful floating plants but frogbit tends to be more popular for its appearance and easier maintenance.

Frogbit vs Red Root Floater

Red root floater (Phyllanthus fluitans) is another aquatic plant often compared to frogbit. Both float on the water surface and have dangling roots. However:

  • Red root floaters stay smaller, typically 1/2” – 1”. Frogbit grows larger.
  • As the name suggests, red root floater has distinctive red roots while frogbit roots are green.
  • Frogbit reproduces faster and is more invasive if not controlled.
  • Red root floaters are more tolerant of different water parameters.

Either can work well in aquariums but frogbit provides more shade and surface coverage due to its spreading growth.

Frogbit vs Water Lettuce

Water lettuce (Pistia stratiotes) is sometimes confused with frogbit but they have some distinct differences:

  • Water lettuce leaves are textured like lettuce and wavy edged. Frogbit leaves are smooth and round.
  • Water lettuce has thicker, spongy leaves that form rosettes. Frogbit leaves lay flat on the surface.
  • Water lettuce gets much larger, up to 6” wide vs frogbit’s 1-2”.
  • Water lettuce needs more light and warmer temperatures than frogbit.

Water lettuce is less commonly used in home aquariums due to its large size. It also reproduces more slowly than quickly spreading frogbit.

Environmental Impact

In outdoor ponds and tanks, it’s important to consider the environmental effects of any plant. Frogbit and duckweed are no exception. Here are a few things to keep in mind:

Does Frogbit Deplete Oxygen?

One common water gardening myth is that plants like frogbit block light and air exchange, reducing oxygen levels. While dense coverage can limit light penetration, frogbit does not directly decrease dissolved oxygen.

Frogbit produces oxygen during daylight hours through photosynthesis like any other aquatic plant. Its long dangling roots also provide surface area for gas exchange. Excessively warm temperatures or decaying plant matter are more likely causes of oxygen depletion.

With routine thinning for light access and plant removal, frogbit does not drastically alter oxygen levels. Aeration can offset any potential decreases.

Can Duckweed Grow Underwater?

Duckweed thrives floating on the water surface, directly accessing air and sunlight. It does not grow fully submerged underwater since it relies on atmospheric carbon dioxide and oxygen.

While duckweed can survive underwater for short periods, it will quickly rise back to the surface. Without access to the air above, underwater duckweed will stop growing and eventually decompose. Maintenance like skimming excess growth is needed to keep duckweed healthy.

Even when deprived of light and air, duckweed can remain dormant. But growth and reproduction require floating access to the water’s surface. Submerged propagation is not possible.

Where to Buy

If you’re ready to add either frogbit or duckweed to your aquarium, here are some options for purchasing:

Frogbit for Sale

Frogbit is widely cultivated and sold due to its popularity in the aquarium trade. Here are some places to buy healthy starter portions:

  • Local pet stores and aquarium shops often stock frogbit in their live plant section.
  • Online retailers like have frogbit bundles available with expedited shipping.
  • r/AquaSwap members frequently offer clippings at reasonable prices.
  • Aquarium plant farms and private sellers on sites like eBay also provide frogbit.

When buying frogbit, inspect for signs of snails, algae, or other pests. Quarantine and rinse new plants before adding to your display tank.

Giant Duckweed

While regular duckweed (Lemna minor) stays very tiny, there is a larger variant called giant duckweed (Spirodela polyrhiza). It provides more visible coverage for those looking for a duckweed on a bigger scale.

Giant duckweed thalli reach 3/16” – 3/8”, much larger than standard duckweed but still considerably smaller than frogbit. It shares the same rapid growth rate and can quickly blanket the water’s surface. Sources to buy giant duckweed include:

  • Online stores like that sell imported variants.
  • Fellow hobbyists on aquarium forums with excess to share.
  • Your outdoor pond or waterway if giant duckweed is present locally.

No matter which duckweed type you choose, prevent it from taking over with routine maintenance. The larger size of giant duckweed provides more visible coverage for aquariums than traditional duckweed.


What are the Benefits of Frogbit?

In summary, here are the main advantages of keeping frogbit:

  • Attractive floating rosettes add natural appeal.
  • Larger leaves provide more shade than duckweed.
  • Trailing roots offer fish fry shelter spots.
  • Growth rate is fast but more manageable than duckweed.
  • Absorbs excess nutrients to prevent algae growth.
  • Oxygenates water through photosynthesis.
  • Low maintenance floating plant adapts to most conditions.
  • Works well in 10+ gallon aquariums.

With its ornamental look and cleaner growth habits, frogbit is the better choice over duckweed for most home aquarists.

Is Frogbit Better Than Duckweed?

When it comes to frogbit vs duckweed, frogbit wins out in most cases. Though tiny duckweed has some benefits for nano tanks, frogbit is easier to control and keeps aquariums cleaner and healthier overall.

Reasons frogbit is superior:

  • Larger size creates shade while allowing light through.
  • Trailing roots are more visually appealing.
  • Slower growth is less invasive and easier to manage.
  • Works well in a wider range of tank sizes.
  • Duckweed can choke out other plants when unleashed.

While duckweed serves some purposes, frogbit’s advantages make it the top aquarist recommendation. With routine pruning, it brings all the benefits of floating plants without duckweed’s aggressive nature.

Adding a starter portion of frogbit to your freshwater aquarium provides natural beauty and valuable water quality benefits for fish and invertebrates. Do your research to find reputable sources and always quarantine new plants. With proper light and nutrients, you’ll soon have a thriving aquatic landscape.