Riccia rhenana

Species description

Care, breeding and tankmates

Plant profile

Placement

Midground

This plant can be cultivated floating at the surface or securely tied to hardscape materials like rocks or wood. Because of its broader thallus, it forms a slightly more textured mat than standard R. fluitans when tied down. It needs strong lighting when placed at the bottom of the aquarium.

Botanical form

free-floating submerged plant

R. rhenana is characterized by a noticeably broader, flatter thallus compared to Riccia fluitans. It exhibits the same dichotomous branching pattern but has a thicker, more robust appearance. It lacks any true root system, existing as a free-floating or epilithic liverwort.

Growth

Medium

It is a fast grower, particularly when supplemented with injected CO2 and strong illumination. It rapidly expands its mass, requiring frequent maintenance to keep it in check. Even in low-tech setups as a floater, it grows steadily.

Substrate

None

Riccia rhenana grows primarily as a free-floating liverwort, eliminating any requirement for an underwater substrate. It does not produce roots for anchoring, instead gathering all its nutritional requirements directly from the water it floats in. If desired in a lower or mid-ground placement, it must be artificially anchored using fine thread or specialized mesh over rocks or driftwood. Burying this plant in gravel or aquasoil will lead to the decomposition of its delicate tissues.

Column fertilization

Recommended

Consistent column fertilization is critical for its success, especially in densely planted tanks where competition is high. Iron and potassium are particularly important to keep the broad fronds looking vibrant. Without adequate column nutrients, growth will stall and discolor.

Root fertilization

None

As a rootless liverwort, it gains absolutely no benefit from root tabs or nutrient-rich substrates. It is completely dependent on the surrounding water for sustenance. Focus entirely on a good liquid fertilizer regimen.

Trimming

Regular

When submerged and attached to hardscape, it must be trimmed very frequently. If the mat gets too thick, the lower portions die, losing their grip, which causes the entire mass to detach and float to the surface. Trim it aggressively and use a fine net to remove the floating debris.

Propagation

Cuttings

Propagation is effortless through mechanical division. Simply separate a portion of the mat or scoop a handful of floating pieces and relocate them. They can be re-tied to new rocks using fine nylon thread or hairnets.

Sensitivity

Moderate

It demands high light levels when submerged; otherwise, it will quickly deteriorate or break free from its moorings. It is sensitive to sudden changes in water chemistry and aggressive algaecide treatments. Ensure strong water flow to deliver nutrients and prevent detritus buildup.

Layout role

Foreground, Midground, Floating, Epiphyte, group

It is primarily used to create luminous, textured carpets or bright accents on hardscape in the midground. Its slightly wider fronds offer a unique textural difference from typical Crystalwort. It is a fantastic plant for producing high levels of visible oxygen bubbles (pearling).