This Moss is really a great grower, it could dominate the tank within a few months after settled in. But it is also a good place for refuging the babies of all sources of fish in a community tank without being eaten. All my guppy and platy babies grow and hide inside the java moss.
Java moss, once it attaches to something and is happy with the light and nutrients in the water, will do quite beautifully. Should you not fulfill its wishes there will be hell to pay, as the strands will not connect to anything no matter how tight you try to tie them on and they will clog filters and get stuck on any other plastic plants that you may have in your tank...the only way to know for sure that it will work is try to get the right type of light. In one aquarium it flourished because I had bluish light and in the other with yellowish light it stayed at same size with very little growth. Good luck!
This plant was a real ego killer. Despite its apparent ease of cultivation (leaving it alone in water), I managed to kill every last bit. I have some herbivorous fish, who generally avoided it, but the golf ball sized chunk I bought lasted about 3 months before disintegrating and rotting. I have heard of a similar looking plant, a sort of false Java Moss that's not nearly as hardy. Oh well, perhaps next time. [Editor's Note: the similar plant referred is probably "Christmas Moss", Fontinalis antipyretica - M.A.]
You can do a lot of fun things with Java Moss. I took a strand and wrapped it through the holes in an upright piece of driftwood, and now it looks like a tree. Also, the control over water quality that this thing has is amazing. I have over a hundred feeder guppies in a 40 L and, not that I recommend doing this, but they are flourishing. Not even a single one has died. I keep forgetting to get my carnivorous fish to feed them to.
Java moss is a great plant and is pretty much a necessity in any planted tank. You would be hard pressed to find a fish breeder without it. It provides a great place for fish to lay eggs, and harbors microfoods for the fry. If you are dealing with a shy species, just pack the tank full of this and they will be happy. I use it in all of my tanks. It is also great for fry tanks and for those tubs of eggs and fry (I keep killifish) that always pop up everywhere. If you trim it frequently in a planted tank you can get it to form very attractive clumps. Untrimmed and it will grow and entangle the other plants.
I've grown Java Moss (V. dubyana) in outdoor tub gardens with mixed results. In a 100 liter glazed pottery aquatic dish garden exposed to 4 or 5 hours of full sun it performed as you would expect, literally growing right out of the pond in no time. Interestingly, strongest growth was evidenced in the cooler winter months here in north Florida (10-13°C). However, plants grown in brightly lit shade, but no direct sun, and under ALL temperature conditions, grew much much slower. This was rather surpising to me considering it's rampant growth noted in indoor, relatively poorly lit aquariums.