Minimum Tank Size: 10 Gallons
Care Level: Easy
Water Conditions: 6-8 ph and Soft to Moderately Hard
Temperature: 22–27 °C (72–82 °F)
Maximum Size: 13 ½ inches (35 cm)
The Java fern (Microsorum pteropus) is an aquatic fern native to South East Asia. There are many different varieties of this fern, and the size of the plant and leaf shape will vary greatly from variety to variety. The four most commonly available are the narrow leaf, the needle leaf, the Windelov and lance leaf.
What makes the Java fern so attractive to aquarists, is that it is one of the easiest aquatic plants to grow. Even in the most basic aquarium setup, it will usually grow like a weed and spread across the aquarium. With that being said, some may take a while for their growth to really ramp up, so don’t worry too much if it doesn’t grow for the first few weeks after it has been planted.
Once it has started growing, it can grow up to 13 ½ inches (35 cm) in height, and up to 6 inches (15 cm) in width. Because of its size, it makes a good addition to the rear or mid-ground of the aquarium.
Java ferns are an incredibly easy plant to grow, and to fail with this plant you almost have to actively be trying to kill it. Unlike many other plants, it doesn’t need a specialized substrate, and it will also do well without the addition of carbon dioxide.
It can be planted nearly anywhere in the aquarium and can be placed on driftwood, rocks or directly onto the gravel (but make sure not to bury it in the substrate). When placing it on driftwood or rocks, it needs to be attached until the roots have fastened to the surface.
To attach the Java fern, you can use either fish line or dark colored thread. Most people tend to prefer thread, since it will dissolve over time after the plant has rooted to the object. Other people prefer to use rubber bands or zip ties, but these are usually noticeable and ugly. If you use rubber bands or zip ties, you may want to remove them after the plant rooted to the surface.
Java ferns do not require any special lighting, and will actually suffer if the lighting is too strong. They will flourish under the incandescent bulbs provided in small, basic aquariums – but they will do especially well under subdued fluorescent bulbs. You can tell if the lighting is too strong for the Java ferns by looking at the leaves. If they start to become brown and transparent, you should cut back on the lighting until the plant recovers.
The one thing to remember with Java ferns, is that they require a regular fertilizer. Because they have no “true” roots, they get most of their fertilizer from the water column. If you want your Java fern to truly thrive, you should add a liquid fertilizer after every weekly water change. Tab fertilizers are useless with Java ferns, since they don’t have a proper root system to utilize them.
Like several other common aquarium plants, Java fern propagate through adventitious plantlets. You will see small adventitious plants begin to form on old leaves, which can be broken off safely from the rhizome.
The new plants can then be attached to their new location, and should be tied down in place while the roots grow over several weeks. As these new plants develop, new rhizomes will form and the whole process can be repeated.
One of the great things about Java fern is that very few fish seem to bother with it – even fish that are constantly on the prowl for a tasty aquatic plant salad. While it probably still won’t survive for long in a goldfish tank, it does do quite well with larger cichlids and many herbivore fish.
There are several reasons given for its relative hardiness around fish that normally devastate plants. Some sources claim that it has a bitter taste, but more reputable sources seem to believe that the tough structure of the leaves make them unattractive to fish.