Java fern

Quick facts

Max height

35 cm

Growth rate

slow

Difficulty

beginner

Placement

midground, background

Propagation

rhizome division

Water parameters

Temperature

18–28°C

pH

6.0 to 7.5

Hardness

1 to 20 dGH

Brackish

tolerated

Light and nutrients

Lighting

low

CO2

not required, but boosts growth and color

Substrate

epiphyte

Feeding

feeds from the water column (use liquid fertilizer)

Substrate

What this plant roots into (or attaches to). The substrate affects both plant nutrition and water chemistry; see each linked page for full effects.

This plant feeds primarily from the water column, so substrate choice matters more for its fish-tank compatibility than for plant nutrition.

With fish

Plant-eating fish

safe with plant-eating fish (tough leaves or unpalatable)

Diggers (corydoras, loaches)

fine - root system or attachment style handles it

Root-disturbing fish

tolerates fish that disturb roots

Habitat

Native to tropical Southeast Asia (Thailand, Malaysia, Indonesia, Philippines, southern China), growing attached to rocks and wood in and alongside streams and rivers. The species (Microsorum pteropus) is one of the most widely recognized aquarium plants in the world. The leathery, dark green fronds grow from a creeping rhizome and reach 15–30 cm tall in the standard form. Several cultivars and variants are commercially available: 'Narrow Leaf' (long, thin fronds), 'Windelov' (forked, lacy tips), 'Trident' (narrow fronds with finger-like projections), 'Philippine' (wider, hammered-texture fronds), and various miniature forms. Java fern is a staple of low-tech aquariums because it tolerates low light, no CO2, and a wide range of water conditions. The tough leaves are unpalatable to most herbivorous fish.

Outdoor pond use

This species transitions to outdoor ponds well, not just indoor aquariums.

Outdoor pond zones (USDA)

8 to 13 (winter low around -12°C or warmer)

Below the minimum zone, the plant won't overwinter outdoors but can still be grown seasonally and overwintered indoors. Several pond-friendly species (water hyacinth, water lettuce, parrot's feather) are regulated as noxious in some jurisdictions; check the legality data on the profile before releasing anything to an outdoor body of water.

Care notes

Among the easiest aquarium plants. Attach the rhizome to driftwood or rocks using super glue, thread, or fishing line. Do not bury the rhizome in substrate; like Anubias, burial causes rot and death. The roots anchor the plant to hardscape surfaces over time. Low to moderate light is ideal. Under high light without CO2, the slow-growing leaves attract algae (especially black beard algae and green spot algae). Growth is slow to moderate: one new frond every 1-2 weeks per growth point. CO2 is not required and makes relatively little difference to growth speed compared to its effect on stem plants. Tolerates pH 5.5-8.0, soft to hard water, temperature 20–28°C. Propagation is by rhizome division and by adventitious plantlets that form on mature leaves (small plantlets sprout directly from the frond surface, eventually developing their own roots and falling off). The plantlets can be collected and attached to new locations. Brown or black spots on leaves are either spore patches (normal reproductive structures, not disease) or early stages of plantlet formation. Trim old, damaged, or heavily algae-covered fronds at the base. Java fern's combination of durability, aesthetic versatility, and fish-resistance makes it the default recommendation for beginners.

Further reading

• Algae: what kind you have and how to fix it
• CO2 injection for planted tanks: what it costs, what it does, and when to skip it