The Anacharis Care Guide: Growing Egeria densa in Cold and Warm Water

Egeria densa is the plant most people meet first, usually in a tube at a chain store, and it has a reputation for being disposable. Grown properly it is neither disposable nor boring — it is the most cold-tolerant common aquarium plant and one of the fastest oxygenators available.

The cold tolerance is the real selling point

Most aquarium plants want 72–82°F. Anacharis is comfortable from around 60°F, which puts it in a very small group of plants that will grow in an unheated tank.

That makes it the default choice for:

• Goldfish and coldwater tanks, where tropical plants sulk
• Ponds, as a submerged oxygenator
• Outdoor tubs and stock tanks through the warmer months
• Unheated rooms where tank temperature swings

It is also unusually tolerant of hard, alkaline water — it will grow to pH 8.5, which is well beyond what most planted-tank species accept.

Goldfish will eat it, and that is a decision not a problem

Goldfish graze Anacharis readily. Depending on your goal, that is either the point or a nuisance.

If you want it as a food source, it works well and grows fast enough to keep up with moderate grazing. If you want it as decoration in a goldfish tank, it will not survive — choose a tougher plant like Anubias or Java Fern instead, or accept that Anacharis is a consumable.

Its roots are an afterthought

Anacharis takes most of its nutrition directly from the water column through its leaves and stems. It produces thin white adventitious roots from the nodes, but these anchor weakly and are not the main feeding route.

Practical consequences:

• It floats loose easily. Planted stems get uprooted by fish and flow. Use plant weights, bury two or three inches of bare stem, or simply let it float.
• Root tabs do little. Liquid fertiliser in the water column is what it responds to.
• Floating is a legitimate way to grow it. It grows faster floating than planted, and in ponds and goldfish tanks that is usually how it is run.

Trimming, and why the bottom goes bare

Anacharis grows toward light and abandons what is behind it. In a tank of any depth the lower stem loses leaves and goes bare and yellowish while the top keeps extending.

The fix is to treat it as a renewable crop rather than a permanent planting. Cut the healthy top six to eight inches, replant those, and discard the bare lower stems. Each cutting grows away immediately. Doing this every few weeks keeps a stand dense.

Trying to nurse a bare stem back into leaf is not worth the effort — it rarely refoliates below the growing tip.

Melting on arrival

Some leaf drop and stem softening in the first week is normal, particularly if the plant has moved between very different temperatures or lighting. Remove any stem that has gone translucent or slimy, because rot spreads along a stem quickly, and replant the firm green sections.

Persistent thin stringy growth with widely spaced leaves means insufficient light rather than a health problem.

Anacharis, Elodea, Egeria — the naming

These names are used interchangeably in the trade and it causes real confusion.

• Anacharis is the common name in the aquarium trade.
• Egeria densa is the current accepted scientific name, and what you are almost always buying.
• Elodea densa is an old synonym for the same plant.
• Elodea canadensis is a genuinely different, smaller, more cold-hardy species also sold as Anacharis.

State restrictions apply to this plant

Egeria densa is a regulated or prohibited species in a number of U.S. states because of its history as an invasive in waterways. This is not a formality — it is one of the most commonly restricted aquarium plants.

Never release it into natural water, and dispose of trimmings in the bin rather than down a drain or into a storm system.

Quick reference

• Light — Low to medium
• CO2 — Not required
• Water — 60–82°F, pH 6.5–8.5
• Feeding — Primarily water column
• Mature height — 12–24 in and beyond
• Propagation — Stem cuttings
• Difficulty — Beginner

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