Java fern (Microsorum pteropus) is a popular and resilient aquatic plant known for its ability to thrive in a wide range of aquarium conditions. Its dark green, flowing leaves make it an attractive addition to a planted tank. Unlike many other aquarium species, Java Fern must not be planted directly into the gravel or substrate. The correct method involves securing the plant to a hard surface, which is then placed in the tank.
The Rhizome: Why Traditional Planting Fails
The reason Java Fern cannot be buried lies in its specific anatomical structure, known as the rhizome. This rhizome is a thick, horizontal stem from which the leaves and hair-like roots emerge. Java Fern is an epiphyte, meaning it naturally grows attached to wood or rock, requiring continuous water flow and high oxygen levels around its stem.
The rhizome is metabolically active and requires direct exposure to the water column to exchange gasses effectively. When buried in dense substrate like gravel, water circulation is restricted and oxygen levels drop significantly. This lack of oxygen causes the rhizome to suffocate, leading to a process called “melting,” where the plant tissue turns black and rots. While the fine roots may be tucked into the gravel for anchoring, the main, thick stem must remain fully exposed.
Secure Attachment Techniques
Since Java Fern cannot be planted directly, it must be secured to a piece of hardscape, such as driftwood or porous rock. This approach ensures the rhizome remains exposed while giving the plant a fixed location in the aquarium. There are two primary methods for attaching the plant to the chosen hardscape material.
One common technique is to use tying materials like cotton thread, fishing line, or small rubber bands. Place the rhizome against the hardscape, and wrap the securing material around both the hardscape and the rhizome multiple times. The tie must be snug enough to hold the plant in place but not so tight that it cuts into the rhizome tissue. Over time, the plant’s roots will naturally adhere to the surface, allowing the temporary tying material to be removed or left to degrade, as with cotton thread.
A more immediate and popular method involves using cyanoacrylate-based super glue, which is aquarium-safe and cures quickly upon contact with water. The gel form of the glue is highly recommended because it is less runny and easier to control during application. Dab a small amount of glue onto the hardscape, and press the Java Fern’s rhizome firmly onto the glue for 30 to 45 seconds. Only glue the rhizome or the roots, avoiding covering the leaves or new growth points entirely.
Once the Java Fern is securely attached to the hardscape, the entire assembly can be placed into the gravel substrate. For a natural look, the hardscape can be partially or completely nestled into the gravel. Ensure the rhizome itself is positioned above the substrate line. This technique allows the plant to appear as if it is growing out of the substrate without risking its health.
Long-Term Care and Growth
Java Fern is low-maintenance, making it an excellent choice for novice aquarists. It thrives best under low to moderate lighting conditions, typically preferring to be positioned in shaded areas or beneath taller plants. Excessive, intense light can be detrimental, leading to algae growth on the leaves or causing the plant tissue to turn brown.
The plant’s primary source of nutrition comes directly from the water column, absorbing dissolved nutrients and fish waste through its leaves and rhizome. Liquid fertilizers containing potassium and trace elements are beneficial, especially in tanks with low fish load or sparse nutrients. It is a slow-growing plant, but healthy growth is indicated by the formation of new leaves from the rhizome.
New plantlets, which are miniature versions of the parent plant, will eventually form on the edges of older, mature leaves. This natural process, known as sporulation, allows for propagation. These plantlets can be gently detached and used to propagate new ferns by attaching them to other pieces of hardscape. The ideal temperature range for this species is generally between 74°F and 82°F, with warmer water encouraging slightly faster growth.