Egeria Densa

Quick facts

Identity

Also known as

Anacharis; Brazilian waterweed; Brazilian elodea; Large-flowered waterweed; Oxygen weed

Synonyms

Elodea densa; Anacharis densa; Philotria densa; Udora densa

Environment

Freshwater

Native to

Brazil, Argentina, Uruguay, Chile

Habitat

Submerged in slow-moving rivers, lakes, and ponds in warm temperate South America, rooting in mud and growing toward the surface

Sourcing

Captive-bred

Conservation

Not Evaluated

Care

Care level

Easy

Growth form

Stem

Max height

6 – 40 in (15 – 102 cm)

Spread

12 in (30 cm)

Growth rate

Fast

Placement

Background, Floating

Water

Temperature

60 – 82 °F (16 – 28 °C)

pH

6.0 – 7.5

GH

3 – 15 dGH

Flow

Low-Moderate

Light

Low

CO₂

Not needed

Planting

Substrate

Any

Feeds from

Both

Fertilizer needs

Low

Colors

Green

Feeding & breeding

Propagation

Cuttings

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Care guide

Overview

South American rivers and ponds from Brazil to Argentina and Chile are the origin of this fast-growing stem plant, long naturalized in temperate waters worldwide. Whorls of narrow green leaves crowd brittle upright stems that root in substrate or simply float. It suits low-tech setups, tolerating wide swings in hardness and light while pulling nutrients straight from the water.

Care

Anacharis is one of the more forgiving stem plants and tolerates a broad range of temperatures, hardness, and lighting, making it a common choice for new fishkeepers and pond owners alike. It grows readily under low to moderate light without added CO2, though more light produces denser, less leggy growth. Because stems are brittle and snap easily when handled, it is best planted or repositioned with gentle movements rather than firm tugging.

Planting & trimming

Strip the leaves from the bottom inch or two of each stem and bury that bare section about an inch into the substrate, spacing stems an inch or two apart so the bases do not shade each other and rot. A planting weight or tweezers helps hold the buoyant stems down until roots form, which usually takes one to two weeks. The plant can also simply be left floating on the surface, where it grows faster but will shade anything planted beneath it.

Fertilizing

Fertilizer is optional since the plant draws much of what it needs directly from the water column, but a basic liquid all-in-one fertilizer helps growth in lean, low-nutrient tanks. Root tabs are not required given its column feeding habit, though a nutrient-rich substrate does no harm. Pale, thin growth under otherwise adequate light usually points to a lack of dissolved nutrients rather than a lighting problem.

Propagation

Propagation is done entirely by stem cuttings: cut a healthy top section a few inches long, remove the lowest leaves, and either replant the cutting or let it float until it roots. Every trim of an established plant effectively produces new starts, and cuttings root readily with no special treatment.

Problems

Sudden transfers between very soft and very hard water can trigger melt or leaf drop, though the reverse direction (hard to soft) tends to be tolerated better. Stems left untrimmed will reach the surface and spread into a shading canopy, so dense mats should be thinned periodically to keep light reaching plants below. Yellowing or thinning tendrils under stable conditions often signal insufficient nutrients rather than disease.

Sources

1. Egeria densa - Tropica Aquarium Plants
2. Anacharis Care: How to Grow Elodea / Egeria
3. Anacharis Care Guide – Planting, Growing, and Propagation - Shrimp and Snail Breeder
4. Elodea densa - Wikipedia

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