The good thing about a java moss background is that it don't just look good, it also works as a natural filter in the aquarium. When the Java Moss grows properly there will a whole microscopical ecosystem in your background, with all kind of small critters. It will provide young fish from egg layers a good food source and the perfect hiding spot at the same time. Some fish like danio's and killies will even lay their eggs in the moss. I have bred these fish in a large community tank without feeding the young at all, they just showed up in the moss at some point, hunting small nearly invisible things.

The hardest part of creating an Java Moss background is getting the moss itself. Over here in the Netherlands it was not available at any petstore I visited, but luckily their are some plant distributors selling it on online. But first you need a foam background, preferably a dark colored one, and setup your tank. When the water is cleared enough start putting some small dots of moss on it, spread it as much as you can. I use paperclips to attach the moss to the background and remove them later on when de java moss has developed enough, that's all. The moss will grow very slowly in the beginning but when it is established you can weed it a few times a month.