A clump of Java on a rock cave.

Java moss seems to be available by the bucket load when you don't need it, but when you want some it is impossible to come by. Back in my fish-keeping days in Germany I knew Java moss only from books, and always really liked the look of it, but I never managed to lay my hands on any. So when I started my 29G, I was sick of waiting, and just ordered a clump via Aquabid. Despite freezing winter conditions and being shipped in a small envelope, it survived the trip unscathed, and is no growing in pretty much all of my tanks.

A small piece of Java exactly where the clump used to be in the previous photo.

Regarding requirements for care Java moss is just as undemanding as Java fern. I have it in some of my tanks in the basement that get only about 4h of fairly dim lighting per day and are not heated. Granted, it doesn't grow fast in there, but it's surviving just fine and looks lush and green. In my opinion Java moss is a must have in any fry tank, since it provides cover ad there always seem to be microscopic critters in there that are an ideal food for the little ones before they can even eat baby brine shrimp.

The one drawback Java moss has is that it competes with your filter as a dirt magnet; that is any particles that float around the tank can get stuck in the Java moss. If that happens and a clump of Java moss looks unsightly I usually take it out and rinse it like a dirty cloth in a bucket of water or even straight under the running tap. This little maintenance usually seems like a small price to pay for such an undemanding and beautiful plant, but in this big tank it became quite nuisance, and I have pulled most of the Java moss out. Small pieces of it continue to grow on the rocks, which gives then a very natural look.

Initially I planted the tank heavily with Java moss. It is fast growing and quickly gives the tank an established look. As the fish grew, the bioload in the tank increased, and the clumps of Java moss turned into unsightly dirt magnets. I pulled the larger clumps out, and am now left with a lighter growth of moss over many of the rocks. In addition, by the time I pulled the moss the Java fern had grown considerably, and was ready to take over the moss' role of main rock covering plant.