Needle leaf hairgrass
Eleocharis acicularis
Also known asMini hairgrass · Slender spikerush
Water parameters
Light and nutrients
Substrate type: nutrient preferred. Propagation: runners.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
| Inert sand (Pool filter sand) | neutral / inert | none |
With fish
Origin and habitat
Distributed across temperate and subtropical regions of North America, Europe, and Asia. The species (Eleocharis acicularis) grows as thin, needle-like stems (hence 'acicularis') in shallow water, wet meadows, and pond margins. This is the taller form of Eleocharis sold in the aquarium trade, distinct from the true dwarf forms (E. parvula/E. pusilla). In the aquarium, the thin stems grow 10–20 cm tall and spread by runners to form a dense, grass-like growth. The extremely fine texture (stems are less than 1 mm diameter) creates a soft, meadow-like effect that's distinct from the broader-leaved dwarf sagittaria or Echinodorus tenellus.
Outdoor pond use
- USDA zones
- 5–10 (winter low around -29°C or warmer)
Care notes
Moderate care requirements. Benefits from CO2 injection and moderate to high light for the best growth, though it can survive in low-tech setups at reduced vigor. The taller growth (10–20 cm) makes it suitable for midground planting rather than foreground carpeting; for a shorter carpet effect, use the dwarf forms (E. parvula/E. pusilla). Plant plugs 2–3 cm apart in nutrient-rich substrate. Root tabs help in inert substrates. The fine texture creates an excellent visual contrast against broader-leaved plants and hardscape. In high-tech setups, runners spread quickly and the plant forms a dense stand within weeks. Trim with scissors to maintain a uniform height and promote horizontal spreading. Old, thick stands develop dead material at the base; thin periodically. Temperature: 15–28°C (tolerates cooler water than most aquarium plants, reflecting its temperate origin). Soft to moderately hard water. Algae can colonize the fine stems under imbalanced conditions; keep nutrients and CO2 stable. In nature-style aquascaping, Eleocharis acicularis is used to create naturalistic meadow or field effects in the midground. Compatible with all fish. The fine stems are fragile and can be uprooted by digging fish like cichlids or large Corydoras; keep with gentle community species if possible. Available as potted or tissue culture specimens from most aquatic plant retailers. A good companion to broader-leaved foreground plants for textural variety.