Riccia fluitans, the floating crystalwort,[3] is an aquatic floating plant of the liverwort genus Riccia which is popular among aquarists as a retreat for young fry and is used in live-bearing tanks.

It can be found floating in ponds, and often forms thick mats on and under the water surface.

When kept about two to three inches below an ordinary fluorescent bulb or in a pond exposed to full sunlight, it will form dense, bright green mats.

Any single branch or antler bud can reproduce into a large colony if the plant is kept in proper conditions.

Floating crystalwort is generally not compatible with duckweeds, as they cover the surface of the water quite rapidly, crowding the Riccia out.