Dwarf hairgrass
Eleocharis parvula
Also known asDwarf spikerush · Eleocharis parvula / acicularis (trade)
Water parameters
Light and nutrients
Substrate type: nutrient rich. Propagation: runners.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Inert sand (Pool filter sand) | neutral / inert | none |
With fish
Origin and habitat
A grass-like sedge of the family Cyperaceae sold as dwarf hairgrass. The trade name covers a few Eleocharis species: the true dwarf forms Eleocharis parvula and E. pusilla, which stay under about 5 cm, and the taller E. acicularis, which reaches 15 cm and is often sold under the same 'dwarf hairgrass' label. Eleocharis is a cosmopolitan genus of 250-plus species; E. parvula in particular is a plant of brackish marshes and mudflats, native across much of the temperate and subtropical world, and grows from a small J- or horseshoe-shaped tuber into tufts of thin, spongy stems. In the aquarium it spreads by underground runners into a dense lawn, one of the most popular foreground carpeting plants. Because the dwarf species are hard to tell apart in the trade, tissue-culture cups are the most reliable way to get a known form.
Care notes
A carpeting plant that does best with strong light and CO2. It needs at least medium light to grow at all, and without CO2 it tends to creep slowly and form sparse tufts that never knit together; with CO2 around 20 to 30 ppm and high light it throws runners fast and closes into a lawn in a couple of months. Split a tissue-culture cup into many small plugs of five to ten blades and plant them a couple of centimetres apart so the runners fill the gaps quickly. It is a root feeder, so a nutrient-rich substrate such as aquasoil matters more than water-column dosing, with root tabs as a weaker substitute in inert sand. Trim the carpet back to about 1.5 to 2 inches whenever it overgrows, which pushes horizontal spread and density, and thin old, thick mats that develop bare dead zones underneath. It likes soft to moderately hard water around 18–28°C, and notably E. parvula tolerates brackish water, unusual among carpeting plants. For low-tech tanks without CO2, Monte Carlo or dwarf sagittaria carpet more easily. It is an ornamental carpet, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.