Riccia Fluitans (Riccia fluitans) Care Guide
A unique liverwort that can float on the surface or be tied to hardscape to form a bright-green carpet of tiny branching fronds.
Compiled by Aquairi from published sources · Published · Updated
Overview
Riccia fluitans is an aquatic plant in the family Ricciaceae. A unique liverwort that can float on the surface or be tied to hardscape to form a bright-green carpet of tiny branching fronds. Made famous by Takashi Amano, it produces beautiful pearl-like oxygen bubbles under high light.
Taxonomy
- Family: Ricciaceae
- Genus: Riccia
- Scientific name: Riccia fluitans
- Other names: Crystalwort
Habitat
A liverwort in the family Ricciaceae distributed worldwide on still freshwater. Naturally floats and forms thick mats; in modern aquascaping it is commonly tied or netted onto stone to grow submerged as a pearling carpet.
Growth requirements
- Light: high (≥80 PAR at substrate)
- CO2: pressurised CO2 recommended
- Temperature: 20-28 °C
- pH: 6-7.5
- GH: 2-12 °dGH
- Substrate: any (rootless or floating)
- Nutrient demand: medium
- Growth rate: fast
- Difficulty: intermediate
Placement
- Maximum height: 5 cm
- Trim every: 7 days
Propagation
In cultivation the plant is propagated by vegetative division or fragmentation.
Propagating Riccia fluitans (Crystalwort) by Division
Overview
Riccia fluitans, the floating crystalwort, is a liverwort that has no true roots. It normally grows quickly at the surface, forming dense mats of bright-green branching fronds. It naturally floats but can be attached to underwater objects such as logs and rocks, where aquascapers grow it as a carpet. Made famous in planted-tank aquascaping, it pearls with oxygen bubbles under strong light.
Propagation Method
Propagation is by simple division: any single branch or antler bud can grow into a large colony in proper conditions. You split a healthy clump into smaller pieces, and each fragment continues to spread on its own.
Step-by-Step
- Lift a healthy clump and pull or cut it into several smaller pieces.
- To carpet: spread a thin layer of pieces over a stone or wood and secure it with plastic mesh or netting.
- To float: simply place the pieces on the surface and let them form a mat.
- Trim regularly so the mat stays thin and light can reach the lower fronds.
- As the colony thickens, lift and divide it again to start new sections.
Conditions for Healthy Growth
Crystalwort thrives in bright light; kept about two to three inches below an ordinary fluorescent bulb, or in a pond in full sunlight, it forms thick mats. Strong light is what drives the prized pearling. As a fast grower it appreciates good nutrients and the added CO2 typical of carpet setups.
Maintenance
Trim the mat often to keep it dense and prevent the lower layer from dying off and detaching. Thin out excess growth so the carpet does not lift away from its mesh, and remove drifting fragments if you want to keep the layout tidy.
Common Challenges
- Hair algae: crystalwort is easily overtaken by hair algae, so keep light and nutrients balanced.
- Crowding by duckweed: it is generally incompatible with duckweeds, which can crowd it out.
- Carpet detaching: an overgrown mat traps oxygen and lifts off the mesh; trim it thin.
- Sparse growth: usually means light is too weak to support a dense carpet.
Propagating Riccia fluitans 'Sunset' by Division
Overview
Riccia fluitans 'Sunset' is a colour selection of Riccia fluitans, an aquatic floating plant of the liverwort genus Riccia. The 'Sunset' form takes on golden-yellow tones under bright light, while the wild species forms dense, bright green mats on and below the water surface.
Riccia lacks roots entirely. It naturally floats, but it can also be attached to underwater objects such as logs and rocks, which is how aquarists create the classic pearling lawn that gives off streams of oxygen bubbles under strong light.
Propagation Method (Division)
Because Riccia has no roots and no stems to cut, you propagate it by division: simply pulling or splitting the floating clump into smaller pieces. Any single branch or antler bud can reproduce into a large colony, so even small fragments will grow into new mats under suitable conditions.
Step-by-Step
- Lift a healthy floating clump of 'Sunset' Riccia from the tank.
- Pull or split it into several smaller pieces with your fingers.
- To carpet a surface, spread a thin layer of Riccia over a stone or piece of wood and hold it down with plastic mesh or fine thread.
- Alternatively, leave divided pieces to float freely so they form new mats at the surface.
- Place the tied surfaces under bright light so the colony fills in and develops golden tones.
Conditions for Healthy Growth
Riccia develops dense, bright green mats when positioned close to strong light such as bright fluorescent bulbs or full sunlight; the 'Sunset' selection colours up best under high light. The plant grows quickly at the surface under proper conditions.
- Light: high — essential for compact growth and pearling.
- Position: 2-3 inches (a few centimetres) below the light source, or attached low for a submerged carpet.
- Growth: fast under strong light.
Maintenance
Tied-down Riccia grows outward and upward, so trim and re-thin the carpet regularly to keep it attached and tidy; the trimmings can be re-tied or left to float as new starts.
Common Challenges
Riccia is vulnerable to hair algae overgrowth, especially in strong light, so keep nutrients balanced and water clean. It is also incompatible with duckweeds, which compete for the same surface space; avoid mixing the two.