Crystalwort: the pearling carpet moss
Riccia fluitans
A bright liverwort tied down into a vivid, oxygen-pearling carpet.
Where it comes from
Riccia fluitans is a floating liverwort found on still fresh water almost worldwide. In the wild it simply drifts in bright green tangles just below the surface — it has no roots and no true leaves.
What to expect
It grows as a mass of flattened, repeatedly Y-forked bright green branches. Famously, the aquascaper Takashi Amano popularised tying it down over stones with mesh or thread to create a vivid, bubbling foreground carpet — a use quite against its floating nature.
How to keep it
Riccia loves light and, under strong light with CO2, pearls dramatically — trapping oxygen bubbles in its branches until the carpet glitters. It has no roots, so it feeds entirely from the water. Left floating it is easy; grown as a tied-down carpet it is more work, because it never truly attaches.
| Parameter | Value |
|---|---|
| Lighting | Medium to high — brighter means denser |
| CO2 | Not required; strongly beneficial |
| Temperature | 20–26 °C |
| pH | 6.0–7.5 |
| Hardness | Soft to moderate |
| Fertiliser | Water-column feeder |
| Substrate | None — floats or is tied to hardscape |
| Growth rate | Fast |
| Placement | Floating or tied as a carpet |
| Difficulty | Medium |
How to tie it down
Sandwich a thin layer between a stone and a piece of plastic mesh, or tie it on with thread, and trim it regularly — it grows outward and, without trimming, thickens until the lower layer dies and the whole mat lifts off and floats. Expect to re-tie it periodically.
What goes wrong
The signature problem is the carpet detaching and floating away as it grows too thick — trim often and keep the layer thin. Trapped debris and low flow also rot the underside. Left simply floating, though, it is one of the easiest bright plants you can keep.
More plants in this series
- Java moss (Taxiphyllum barbieri) — the easiest tie-down moss
- Floating fern (Salvinia natans) — the easy surface floater