Thor's Hammer Java Fern

Microsorum pteropus Thor's Hammer

📍 Southeast Asia

Thor's Hammer Java Fern is a distinctive cultivar of Microsorum pteropus featuring unique, compact hammer-shaped or club-shaped fronds that set it apart from standard Java Fern varieties. This slow-growing epiphytic fern displays deep green coloration and creates an attractive, sculptural appearance in aquascapes. It is an excellent choice for beginners due to its extreme hardiness and minimal care requirements.

Tank Mates

Amano Shrimp

Non-destructive, will not uproot or damage rhizome; excellent algae control

excellent

Neon Tetra

Peaceful community fish; small size does not disturb epiphytic plants

excellent

Otocinclus

Algae eater that respects plant structure; will not damage fern fronds

excellent

Dwarf Gourami

Peaceful mid-water swimmer; generally ignores plants

good

Corydoras Sterbai

Bottom-dweller that will not disturb attached fern; beneficial for tank maintenance

excellent

Common Diseases

Rhizome Rot

Symptoms

Blackening or softening of the rhizome; fronds detach easily; mushy texture when touched

Treatment

Ensure rhizome is not buried in substrate and has good water flow; remove affected portions with sterile scissors; improve water quality and reduce organic buildup

Melting on Transition

Symptoms

Fronds turn translucent, become mushy, and dissolve within days of planting

Treatment

Common when moving from emersed to submersed form; trim affected fronds and allow new growth; maintain stable water parameters and ensure adequate light

Algae Overgrowth on Fronds

Symptoms

Green or brown algae coating leaves; fronds appear dull and covered in film

Treatment

Increase water flow around plant; reduce lighting duration; introduce algae-eating fauna (Amano Shrimp, Otocinclus); manually remove algae with soft brush

Iron Deficiency

Symptoms

New fronds emerge pale or yellowish; older fronds remain darker green

Treatment

Add comprehensive liquid fertilizer containing iron and trace elements; dose according to product instructions; perform 25% water change weekly to prevent nutrient accumulation

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Quick Facts

co2: not required
lighting: low
placement: epiphyte
substrate: Epiphyte—attach rhizome to driftwood or rock using thread or fishing line; do not bury. Prefers inert substrate or no substrate contact.
growth rate: slow