Giant Hairgrass
Eleocharis montevidensis
Also known as Tall Hairgrass, Giant Spike Rush
Plantae›Tracheophyta›Magnoliopsida›Poales›Cyperaceae
📍 Americas (North and South America)
The tallest commonly kept Eleocharis species, producing stiff, dark green needle-like blades up to 30–50 cm (12–19.5 in) tall. Creates a dramatic, grass-like background that mimics riparian meadows. Unlike dwarf hairgrasses, it does not form a dense carpet but instead grows as individual clumps. Very undemanding and one of the few Eleocharis that thrives without CO₂ injection. Excellent for paludarium setups or tall tanks where vertical structure is desired.
Community Photos
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by @karleenmendoza
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Tanks keeping this 🌿
Growing in 1 tankCommunity tanks featuring Giant Hairgrass.
Compatible Livestock
Small, peaceful algae grazers that won't damage plant leaves and benefit from the cover provided by tall grass clumps
Peaceful schooling fish that add color and movement without harming plants; thrive in similar water parameters
Excellent algae control and plant-safe; their activity complements the static structure of hairgrass
Complementary foreground plant that creates layered aquascaping with Giant Hairgrass in the background
Hardy companion plant with different growth form; both thrive without CO₂ and create diverse texture
Peaceful dwarf cichlid that appreciates plant cover; may occasionally uproot plants but generally compatible
Common Diseases
Nutrient Deficiency
Yellowing leaves, stunted growth, pale coloration, leaf tips browning
Add comprehensive liquid fertilizer or root tabs; ensure adequate lighting and water circulation; test water for macronutrients (nitrogen, phosphorus, potassium)
Algae Overgrowth
Green or brown algae coating leaves, reduced light penetration, plant appearance dulled
Reduce lighting duration to 8-10 hours daily; increase water changes; add algae-eating fish or shrimp; manually remove visible algae
Melting
Leaves becoming translucent, mushy texture, rapid leaf loss
Improve water quality with frequent partial water changes; ensure stable temperature and pH; trim affected leaves; increase aeration and reduce organic buildup
Slow Growth or Stagnation
Minimal new leaf development, no visible growth over weeks, leaves remaining small
Increase light intensity and duration; add fertilizers; improve water circulation; check for adequate substrate nutrients; ensure temperature is within optimal range (15–28°C)
Tips from the community 💡
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Quick Facts
- co2
- Not required
- light
- Low to high
- max size
- 30–50 cm (12–19.5 in) tall
- placement
- Background
- substrate
- Any
- growth rate
- Medium
Water it likes
- ph
- 6.0–8.0
- notes
- Grows as clumps rather than a carpet. Very hardy and undemanding — great for beginners wanting a tall grass look.
- hardness
- 2–15 dGH
- temperature
- 138–180°F (59–82°C)
Legality
No state or federal restrictions on record for this species.
Not legal advice, and possibly incomplete or out of date. Rules vary by state and locality and change over time — always confirm the current regulations with your state wildlife or agriculture agency before buying, keeping, or shipping this species.