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PlantFreshwaterIntermediate

Eleocharis sp. "montevidensis"

Eleocharis sp. "montevidensis"

Eleocharis sp. 'montevidensis': imposing slender stem plant for the background, suitable for creating floating green screens in tall aquariums.

Taxonomy
Class:Liliopsida
Order:Poales
Family:Cyperaceae
Genus:Eleocharis
Species:Eleocharis sp. "montevidensis"

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Water Temperature

18 - 27 °C

pH Value

5.5 - 7

Water type

Freshwater

Light

Medium - High

CO2

Medium - High

Expected height

55 cm

Expected width

20 cm

GH

0 - 20 dGH

KH

0 - 14 dKH

Species description

Native to South America, particularly the regions around Uruguay and Argentina. It grows in shallow marshy waters, sandy swamps, and riverbanks subject to seasonal flooding. Belongs to the Cyperaceae family, genus Eleocharis. The species montevidensis is known to be one of the tallest and most robust hairgrass variants commercially available. Characterized by vertical cylindrical stems, hollow inside, growing densely from a creeping rhizome.

Care, breeding and tankmates

Tolerant regarding water chemistry; ideal pH between 6.0 and 7.5. Prefers soft to medium water hardness (KH 2-12) and temperature between 15 and 28 °C. Can be subject to yellowing if iron is lacking in the substrate. Filamentous algae can cling to the stems if water circulation is poor.

Geographic Origin and Distribution

This species originates from: South America.

Origin

Extra-Amazon South America

Plant profile

Placement
Midground

Because of its potential to reach the water surface, it is best placed in the background of the aquarium. It can be planted in dense clusters to hide aquarium equipment such as heaters or filter intakes. In taller aquariums, it creates a striking vertical accent. It should be given enough space so it does not overshadow shorter foreground species.

Botanical form
Rhizome

Eleocharis sp. 'montevidensis' features long, elegant stems or leaves that grow vertically towards the light source. It can form dense thickets that provide excellent hiding spots for fish and fry. The leaves are typically bright green, adding a vibrant splash of color. Its structure is quite flexible, allowing it to sway beautifully in strong water currents.

Growth
Medium

This plant exhibits a rapid growth rate, often reaching the water surface within a matter of weeks. The growth can be accelerated even further with intense lighting and CO2. Its fast growth makes it an excellent candidate for newly set up tanks to combat algae. Frequent trimming will be required to keep it from taking over the tank.

Substrate
High

Eleocharis sp. "montevidensis", known as Giant Hairgrass, requires a robust and nutrient-rich substrate to support its remarkably tall, needle-like growth. Due to its size, it develops a deep and extensive root system that demands a substrate depth of at least 5-7 centimeters for secure anchoring. A fertile aquatic soil is crucial, as this species draws significant amounts of minerals directly from its root base to fuel vertical growth. While a fine-grained substrate is preferred, it can tolerate slightly coarser gravels provided that root tabs or base fertilizers are abundant.

Column fertilization
Recommended

Liquid fertilization is very effective for this species, as it readily absorbs nutrients through its leaves. A balanced liquid fertilizer containing both macros and trace elements should be dosed regularly. Potassium and iron are particularly important to maintain strong stems and vibrant leaf color. Without sufficient water column nutrients, lower leaves may begin to degrade.

Root fertilization
None

While it draws heavily from the water column, a nutrient-rich substrate will produce the most robust specimens. Root tabs placed near the base can provide a secondary nutrient source and anchor the plant securely. A good substrate helps prevent the stems from rotting at the base. However, it can still grow reasonably well in inert substrates with adequate liquid dosing.

Trimming
Occasional

Regular pruning is necessary to manage its height and encourage lateral branching. You can simply cut the upper portion of the plant and replant the healthy tops to increase the density of the group. If the plant reaches the surface, it may bend and shade other plants, so timely trimming is crucial. Discard any old or decaying lower stems during maintenance.

Propagation
Cuttings

Propagation is straightforward and usually achieved through cuttings or division, depending on its specific morphology. If it produces runners or side shoots, these can be separated once they have developed roots. Replanting top cuttings is the easiest way to multiply stem-like growth. It is a highly prolific plant under the right conditions.

Sensitivity
Moderate

It is generally a very resilient plant, adaptable to a wide range of water parameters. However, sudden changes in water chemistry or temperature can sometimes cause melting. It requires adequate light reaching the lower portions; otherwise, it may drop its bottom leaves. It is mostly unaffected by typical aquarium medications.

Layout role
Midground, Background

This plant excels as a background filler, providing a tall, green curtain that adds depth and volume. It contrasts well with red plants or broad-leaved species in the midground. Its vertical lines can help draw the eye upwards, enhancing the sense of scale in the aquascape. It is also highly useful in breeding tanks for fish that require dense cover.

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

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Eleocharis sp. "Belém"

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Last updated: 06/16/2026
Eleocharis sp. "montevidensis" Care Guide & Tank Setup | Atlarium