AQUATIC PLANTS & LIVESTOCK

Java Fern

Hardy epiphyte with narrow divided leaves; propagates from plantlets on old leaves.

Planting stage Plants

Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking

Plants

Specification
Type	Rhizome, epiphyte
Light demand	Low to medium
CO₂ demand	None required
Growth rate	Slow to moderate
Leaf length	15–35 cm
Placement	Attached to wood or stone

Technical parameters
pH range	6.0–7.5
Temperature	20–28 °C
Propagation	Plantlets on old leaves
Potassium need	High — deficiency causes black spots
Pruning	Cut old leaves at the rhizome
Varieties	Narrow, Windelov, needle leaf

Java fern is a rhizomatous epiphyte from Southeast Asia with long, narrow, deeply lobed leaves. Like Anubias it is mounted rather than planted, and like Anubias its rhizome rots if buried.

It is more tolerant than Anubias in two respects: it grows faster, and it propagates itself. When a leaf ages, the plant grows small plantlets along its underside, and those plantlets detach and can be moved. That makes a single purchase into a supply of new plants over a year or two, and it makes Java fern one of the few plants that actively fills a tank for free.

There are several varieties with different leaf forms — the standard narrow leaf, the broader "Windelov" with forked tips, and a needle-leaf form. Mixing two varieties on the same piece of wood gives a much more natural look than one variety used throughout, because the eye reads the difference in leaf shape as different species growing together.

Safety and welfare

Do not bury the rhizome. Mount it or wedge it into a crevice.
Black spots on Java fern leaves are usually potassium deficiency, not disease. Treat with a potassium supplement rather than removing the plant.
Trim with sharp scissors and remove every cutting. Leaf fragments left floating will grow into new plants in the filter intake.

Using it well

Leave old leaves in place until the plantlets on them are large enough to move. Removing them early loses the next generation.

Java fern in a high-light, high-CO₂ tank grows darker and thicker but attracts algae. It does best in the mid-ground where light is moderate.

Potassium deficiency shows as black spots and yellowing between veins. It is the most common nutrient problem with this plant specifically.

Lives with

AnubiasCherry shrimpNeon tetraDriftwoodDragon stone

Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.

Java Fern

Using it well

Lives with

Works alongside