Anacharis

Quick facts

Max height

100 cm

Growth rate

fast

Difficulty

beginner

Placement

background, floating

Propagation

stem cuttings

Water parameters

Temperature

10–28°C

pH

6.0 to 8.5

Hardness

3 to 25 dGH

Cold water

tolerated (unheated setups)

Light and nutrients

Lighting

low

CO2

not needed

Substrate

any

Feeding

feeds from the water column (use liquid fertilizer)

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

will be eaten by mollies, silver dollars, large goldfish, and other plant-grazers

Diggers (corydoras, loaches)

fine - root system or attachment style handles it

Root-disturbing fish

tolerates fish that disturb roots

Habitat

Native to temperate and tropical waters across the Americas, from southern Canada through the United States to Argentina. The genus Egeria (E. densa is the most common species in the trade, sometimes sold as Elodea densa) grows in slow-moving rivers, ponds, lakes, and ditches. Anacharis is one of the most widely distributed aquatic plants in the world, introduced on every continent except Antarctica for the aquarium trade, research, and as oxygenating pond plants. It forms dense, weed-like masses of long, branching stems with whorls of small bright green leaves. The plant grows both submerged and as floating stems near the surface. It's one of the most effective nutrient sponges available, rapidly absorbing nitrate, phosphate, and ammonia from the water column, which makes it popular for new tank cycling, goldfish tanks, and overstocked community tanks.

Outdoor pond use

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

Outdoor pond zones (USDA)

5 to 13 (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

Among the easiest aquarium plants. Grows in virtually any conditions: low to high light, no CO2, soft or hard water (actually prefers harder water, GH 8+), and a wide temperature range (15–28°C). The cold tolerance makes it one of the few aquarium plants suitable for unheated goldfish tanks. Plant stems in the substrate or let them float; the plant grows either way. Floating stems produce a tangle of roots from the nodes that serves as fry cover and shrimp habitat. Growth is fast under moderate to high light; weekly trimming is necessary to prevent it from taking over the tank. Cut tops and replant to propagate. The stems are brittle and break easily during maintenance, creating fragments that each grow into new plants, which is part of why it's so invasive in the wild. In hard water with good light, the stems can grow 5–10 cm per week. In low-tech setups, it's slower but still reliable. Nutrient demands are moderate; it pulls what it needs from the water column. Anacharis competes with algae for dissolved nutrients, which is one of its most useful qualities in new or unbalanced tanks. The main downside is aesthetic: it looks somewhat weedy and monotonous compared to more refined planted tank species. Many keepers use it as a functional plant (nutrient export, fry cover) rather than a design element.

Further reading

• How to cycle a fish tank