Species guide
Riccia fluitans Care Guide (Crystalwort)
Aquatic plant
Riccia fluitans (crystalwort) is a liverwort, not a true moss. Float it for fry cover and nutrient export, or tie it to stone/mesh for a high-light carpet that pearls. It will escape. Plan on skimming floaters. It is not Fissidens, not Christmas moss, and not HC.
- Liverwort
- Float or mesh-tie
- High light if carpeted
- Escapes easily
Quick facts
| Light | Low–medium floating; high if tied as carpet |
|---|---|
| CO₂ | Needed for a tight pearling carpet; not for a float layer |
| Temp | 18–28 °C |
| Mode | Float OR mesh/hairnet on stone — pick one |
| Attach | Mesh + thread; glue alone rarely holds |
| Escape | Constant — skim weekly |
| Pearling | Famous under high light + CO₂ |
| Height | 1–3 cm tied; unlimited floating mats |
Overview
Riccia is the plant that refuses to stay where you put it. Floating: easy, great with bettas and fry. Carpet: Amano-era trick with mesh, high light, and CO₂ — then it still escapes. Do not confuse it with Fissidens or Christmas moss.
True soil carpets: Monte Carlo · glosso · HC Cuba · hairgrass. Triangle: light/CO₂/fert. Budget carpet tank: 20-gal.
Float it or jail it
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Step 1
Decide float vs carpet on day one
Float = no attach, skim extras. Carpet = mesh/hairnet over a stone, thread tight, high PAR + CO₂.
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Step 2
If carpeting, use mesh — not hope
A rubber band or two glue dots will fail. Classic method: hairnet + stone.
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Step 3
High light only if tied
Floating Riccia burns and yellows under a blasting LED. Shade it or move the lamp.
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Step 4
Skim every water change
Loose thalli seed the filter and overflow. A turkey baster is your friend.
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Step 5
Don’t dose algicide on a Riccia carpet
It is thin tissue. Mechanical remove + shrimp instead.
Common problems
Turns yellow and sinks
Why: Too much light floating, or old tissue.
Fix: Shade; harvest and keep the green tips.
Carpet lifts off the stone
Why: Mesh too loose or gas bubbles under the mat.
Fix: Retie; vent bubbles; keep CO₂ stable not spiking.
Took over the whole surface
Why: You floated it with no skimming.
Fix: Harvest 70%. Feed it to compost, not the drain (invasiveness).
No pearls, dull green
Why: Low light/CO₂ on a ‘carpet’ attempt.
Fix: Accept float mode or upgrade triangle.
Tank mates
Gear for this species
Aquarium Glue, Clear Coral Glue for Plants, Rocks, Moss, Coral, Stone, Wood – Quick Drying, Fish Safe, Freshwater & Saltwater Aquascaping – 5g (2PCS)
Uses: - Used to attach moss/epiphytes to rocks, driftwood... - Can be applied when the plant or substrate is wet - Gel form, does not dry out like 502 glue over time
Landen Aqua Soil Substrate for Natural Planted Aquarium, Plant or Shrimp Stratum, Clay Gravel and Stable Porous Substrate for Freshwater Aquarium, Black Color 40lbs
Substrate vàng chuẩn Iwagumi / Nature Aquarium.
20 gallon carpet budget — Riccia is a floater unless you mesh-jail it — plan for escapees either way
FAQ
Is Riccia a moss?
No. It is a liverwort. Care is closer to a floating plant than to Java moss.
Can it be a beginner carpet?
No. Monte Carlo or hairgrass. Riccia carpet is a high-tech stunt.
Will it oxygenate the tank?
Pearling looks dramatic. Surface floaters also shade and cut gas exchange if they seal 100% — leave gaps.
Safe to dump extras outside?
Do not dump in waterways. Compost or trash.
Riccia vs duckweed?
Duckweed is smaller, faster, harder to kill. Riccia thalli are chunkier and more ‘scape-able.’
Need fertilizer?
Lean liquid if light is medium–high. Floating mats pull ammonia/nitrate — still test, don’t guess.
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