A fast-growing floating plant that is significantly larger than common duckweed (Lemna minor). It is easily identified by its distinct reddish-purple undersides and a cluster of multiple roots dangling from each frond. It is excellent for natural nutrient export and shading, though it requires frequent culling to prevent it from completely blocking light to underlying plants.
Giant Duckweed At a Glance
Giant Duckweed Care and Setup
Layout Fit
Giant Duckweed usually works best at the surface and needs enough room to mature at about 3 cm tall and 1 cm wide.
Water Window
Aim for freshwater conditions with gentle water movement, plus 15 to 30 °C, pH 6 to 8, and 2 to 15 dGH.
Upkeep Rhythm
Expect fast growth with high maintenance. Plan to trim and thin it regularly so it does not crowd slower plants.
Giant Duckweed Care Guide Summary
The Giant Duckweed is a floating plant that usually works best at the surface. Give it room to reach about 3 cm tall and 1 cm wide, so the mature plant still fits the layout. It rewards stable conditions and a deliberate routine with light, nutrients, and pruning. In day-to-day care, it responds best to low light, freshwater conditions, and gentle water movement. It usually grows well without added CO2. Keep this species within a comfortable range of 15 to 30 °C, pH 6 to 8, and 2 to 15 dGH.
Giant Duckweed Planting, Feeding & Maintenance
The Giant Duckweed does best when the setup matches the way it naturally grows. It is best left free-floating so the plant can spread naturally at the surface. Most of its nutrition comes from the water column, so steady liquid fertilization matters more than heavy root feeding. It does not need a nutrient substrate to stay viable in an aquarium. Keep the routine steady: low light and low nutrient demand usually give better results than big swings from week to week. It is usually treated as a submerged display plant rather than an emersed grow-out choice.
Giant Duckweed Compatibility
Use these signals as quick context, not hard rules. They help you judge how well Giant Duckweed is likely to stay in place, tolerate curious fish, and contribute real cover in a mixed planted tank.
Aquarium Benefits
The Giant Duckweed can work very well in a mixed tank, but its value depends on how well it handles fish pressure and how much usable cover it really provides. It is a poor match for plant-eating or rough fish because the leaves are easy for them to damage. Its anchoring strength is limited early on, so avoid pairing it with persistent diggers or boisterous substrate movers. It creates meaningful shelter for fry, shrimp, and cautious fish. Its canopy can shade neighboring plants, so leave space around lower growers that need direct light. Aquarists also lean on it for surface cover, shelter for fry, shelter for shrimp, a grazing surface, and breaking up sight lines, not just for appearance.
Giant Duckweed Propagation
This species is usually propagated by offsets and physical division. With fast growth and high upkeep, it can overtake nearby space if you let maintenance slide. That gives you a better sense of whether simple trimming is enough or whether it is smarter to plan division, replanting, or thinning before the layout closes in.
Frequently Asked Questions About Giant Duckweed
Is Giant Duckweed a good beginner aquarium plant?
This is not the easiest starter plant. It is considered a beginner species that requires high upkeep, and it rewards aquarists who can keep light, nutrients, and CO2 stable.
Where should Giant Duckweed be placed in an aquarium?
This plant usually looks best at the surface. At full size it can reach about 3 cm tall by 1 cm wide, so leave room for it to mature. It is best left free-floating at the surface.
Does Giant Duckweed need strong light or CO2?
For the best results, provide it with low lighting. Additionally, it usually grows well without added CO2.
What water conditions suit Giant Duckweed?
Aim for freshwater conditions, gentle water movement, and a range around 15 to 30 °C, pH 6 to 8, and 2 to 15 dGH to keep this species inside its comfort zone.
How does Giant Duckweed spread or help the aquarium?
It is usually propagated by offsets and physical division. In the display tank, aquarists value this plant for surface cover, shelter for fry, shelter for shrimp, a grazing surface, and breaking up sight lines.
Plants That Grow Well With Giant Duckweed
These plants share compatible water parameters and growth habits with Giant Duckweed, making them reliable companions in a shared aquascape.
Common Duckweed
Lemna minor
Stringy Moss
Leptodictyum riparium
Water Spangles
Salvinia minima
Water Fern
Azolla filiculoides
Süßwassertang
Lomariopsis lineata
Pelia
Monosolenium tenerum
Side-by-side comparisons for Giant Duckweed
These guides compare Giant Duckweed directly with another plant, helping you choose between similar roles, care needs, and layout tradeoffs.
Asian Watermoss
Salvinia cucullata
Carolina Mosquito Fern
Azolla caroliniana
Common Duckweed
Lemna minor
Floating Fern
Salvinia natans
Red Root Floater
Phyllanthus fluitans
Water Fern
Azolla filiculoides
Fish That Suit Giant Duckweed
These fish pair well with Giant Duckweed based on shared water preferences and temperament, helping you build a balanced tank around this plant.
Bladder Snail (Pest Snail)
Physella acuta
Keyhole Cichlid
Cleithracara maronii
Bolivian Ram
Mikrogeophagus altispinosus
Agassiz's Dwarf Cichlid
Apistogramma agassizii
Ramshorn Snail
Planorbidae fam.
Malaysian Trumpet Snail (MTS)
Melanoides tuberculata
Related plant profiles
These cards open plant profiles directly. They are chosen by overall care, layout, and growth-pattern similarity, rather than a side-by-side comparison guide.
Common Duckweed
Lemna minor
Common Duckweed is a notoriously fast-growing floating plant that reproduces rapidly through budding and fragmentation. While it is excellent at absorbing excess nutrients and providing cover for fry, it requires frequent culling to prevent it from completely smothering the water surface and blocking light to the plants below.
Giant Salvinia
Salvinia molesta
A highly prolific floating fern known for its thick, folded leaves covered in unique egg-beater shaped hairs that make the plant intensely water-repellent. While excellent at taking up excess nutrients and providing protective cover for fry and shrimp, it grows extremely fast and requires frequent scooping to prevent it from completely suffocating the water surface and blocking all light.
Broadleaf Sagittaria
Sagittaria latifolia
A robust, fast-growing marginal plant that can be grown submerged in large aquariums. While famous for its large, arrowhead-shaped emersed leaves, it produces long, strap-like foliage when grown completely underwater. It spreads vigorously via thick stolons and forms a strong root system, often attempting to breach the water surface.
Floating Fern
Salvinia natans
Salvinia natans is a fast-growing, rootless floating fern characterized by small, oval leaves covered in water-repellent hairs. It is excellent for absorbing excess nutrients from the water column and providing a secure canopy for shy fish and fry, but it requires regular culling to prevent it from completely blocking light to submerged plants.
Water Spangles
Salvinia minima
A fast-growing, free-floating aquatic fern characterized by small, round to oval leaves covered in stiff, water-repellent hairs. It possesses no true roots; instead, modified submerged leaves dangle in the water column to absorb nutrients. It acts as an excellent nutrient sink and provides dense surface cover, making it ideal for shading the aquarium and offering refuge for fry and shrimp. It requires calm surface waters to thrive and multiplies rapidly.
Water Fern
Azolla filiculoides
Azolla filiculoides, commonly known as Fairy Moss or Water Fern, is a highly prolific floating fern. It forms dense, velvety mats on the water surface and is famous for its ability to fix atmospheric nitrogen via a symbiotic relationship with cyanobacteria. Under high light or nutrient limitation, its leaves develop a striking reddish hue. While it provides excellent cover for fry and resting areas for surface-dwelling species, it grows aggressively and requires frequent culling to prevent it from blocking essential light to submerged plants.