Needle leaf hairgrass

Quick facts

Max height

10 cm

Growth rate

moderate

Difficulty

beginner

Placement

foreground, midground

Propagation

runners

Water parameters

Temperature

4–28°C

pH

5.5 to 8.0

Hardness

2 to 20 dGH

Cold water

tolerated (unheated setups)

Light and nutrients

Lighting

medium

CO2

not required, but boosts growth and color

Substrate

nutrient preferred

Feeding

feeds from both water column and roots (liquid ferts plus root tabs)

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)

may get uprooted by active diggers

Root-disturbing fish

tolerates fish that disturb roots

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

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

Outdoor pond zones (USDA)

5 to 10 (winter low around -29°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

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.

Further reading

• How to cycle a fish tank
• Water chemistry for fishkeepers: pH, GH, KH, and what they mean