Riccia fluitans is a floating plant, that grows rootless, short, interlocking strands that when bunched together looks similar to moss.
  

In recent years, a popular method of aquascaping has been to use riccia to simulate the mossy look on rocks, wood, or just about any object that is only limited by your imagination.   Once attached, its fairly undemanding needing only bright light and CO2 injection. The only maintenance involved is keeping the plant trimmed close to its netting to prevent  overgrown clumps from breaking off and  floating to the surface.

Straight Riccia:
Take a clump and evenly spread it across the object without stacking it on top of each other, (you should be able to just barely see the object through the Riccia) Wrap it with nylon thread, fishing line, or a nylon hair net. Cotton thread will disintegrate and the Riccia will then float to the surface! As the Riccia grows out thicker, it will cover up the netting.

Riccia mixed with Java or Willow moss
Layer the Riccia as described above, and then on top of the Riccia layer some Java moss or Willow moss, allowing some of the moss to stick out on one side beyond the Riccia. Top that with another layer of Riccia. Wrap the whole thing with thread or netting. You now have a Riccia-moss sandwich!

Riccia with Dwarf hair grass
As strange as this may sound, this can be an interesting look when making a Riccia carpet in the foreground. After attaching the Riccia, take a small Dwarf hair grass plant and bend it over the Riccia. Wrap it a couple of times with thread. Plant the rooted part of the hair grass in the substrate.
 
 

Where to put it

Riccia can be placed most anywhere in the tank as long as it gets direct overhead light. Any shading will have an affect on its growth, varying to the degree of the shadows. Riccia Carpet Riccia can be used to cover an area of the substrate by attaching to round rocks, or flat pieces of slate, wood or any other like object. In an artistic display, one important element is creating a graded or sloping substrate. No matter how good a job you do of terracing, it is always a challenge to keep the sloped substrate from settling forward. By simply using carefully placed rock and wood to create a gradual incline, the Riccia creates the illusion of a sloping, lushly planted tank bottom. Riccia Frame You can create a framed viewing foreground perspective by having a carpet of Riccia on the bottom, and a pillar of Riccia going up the front corner wall.     Simply use a long piece of wood or similar object going from the gravel to the water surface.

The Riccia should only be attached to side of the object that is facing outward. The opposite side will get no light, and the Riccia there will only begin to decompose. Highlights Riccia can look just as impressive limited to only a few highlighted focal points. For example, a single Riccia rock in the foreground with a larger dark green Java moss rock behind it makes a sharp contrast. The layered look   As long as it can get enough light, you can have Riccia at various levels of the aquarium, wherever you can  put a branch or rock. Imagine creating a stepping stone, ladder, or shelved look!   Riccia junk   For something different, imagine a true underwater scene, a lake bed littered with human refuse. What would you see? Scraps of metal, tools perhaps, how about a pair of baby shoes? An eating utensil? Now imagine re-creating this scene in your aquarium with real life man made objects covered in mossy Riccia! Riccia is the paint, the aquarium the canvas, and you are the artist!