[lostriver]

You can use Java moss, but it is a bit scraggly and grows longer than the tropical mosses on a substrate floor. It needs a lot of trimming. On the high side, if you don't like it, it rips off easily. I like it best when it climbs water falls and drip walls, where it does a great job of filtering the water. I generally have a heck of a time growing the tropical pillow or sheet mosses-- probably not enough light and ventilation for them. Once in awhile they will take hold in one particular area, but in general, mine never really thrive all over, least of all where I really want them to grow. Then on occasion some kind of short moss will show up "spontaneously," and thrive on a substrate. I have one of these now that cropped up in a nursery/quarantine tank for froglets that has a shallow base of wet cocoanut fiber. I have no idea what it is, but will try to transplant it to one of the more permanent tanks and see what happens from there.