Anacharis Facts, Care & Planting Guide (Elodea densa)

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Anacharis is similar in appearance to other oxygenating aquatic plants like hornwort (Ceratophyllum demersum) and waterthymes (Hydrilla verticillata), however they tend to appear less bushy than their counterparts. Their thin 1 to 4 cm (0.4-1.5 in) leaves form rings or whorls that extend up the length of delicate stems attached to a single root base. These plants appear anywhere from bright green to dark, seaweed-like green in color. Anacharis is a favorite learning tool of science teachers across the globe. The needle-like leaves of anacharis are only one to two cells thick and are an ideal way to introduce students to the plant cell structure, with the chloroplasts and cell walls easily seen under simple microscopes.

Anacharis has many names including Brazilian elodea, egeria, Brazilian waterweed, common waterweed, dense waterweed, and leafy elodea. One of the reasons anacharis has many names may be because of the number of places it has cropped up across the globe. Originally from eastern South America, anacharis has spread from its native areas in Brazil, Uruguay, and Argentina to all continents except Antarctica.

Does Anacharis Have Any Benefits?

This plant is more than just a pest, though. Anacharis is valued for its ability to take up water pollutants and inhibit the growth of harmful bacteria by limiting the nutrients in the water and releasing antibacterial chemicals. A recent study found that the addition of anacharis to a widely used wastewater treatment model increased the effectiveness of the system, which uses certain types of bacteria to decontaminate water, and lead to a significant decrease in the production unwanted chemical byproducts. Another research group in Malaysia found that anacharis could be used to remove arsenic and zinc from wastewater produced by gold mining.

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Anacharis Fact Sheet:
Aquatic Perennial Herb
USDA 5-13
Partial Sun to Partial Shade
June – August (Summer)
Spread up to 3m (10ft)
Up to 4m (13ft)
pH 6.5-7.5

Anacharis Growth, Hardiness & Wintering

Many anacharis that look like submerged pine branches in a pond
Photo by Lamiot, CC BY-SA 4.0, via Wikimedia Commons

Anacharis grows rapidly and have been known to reach heights of 3m (10ft) in the wild. Thick growths of anacharis look like masses of submerged pine branches because their stalks grow both upward and sloped along the water’s surface. Anacharis produces a tri-petal white flower with a yellow center about 12-20 mm (less than 0.75 in) in diameter. These flowers bloom in the summer, but little information has been recorded on their blooming duration. Similarities with other plants in their family, however, suggest each flower is likely short-lived.

Anacharis can survive in water temperatures from 15 to 30° C (59 to 86° F), and prefers a neutral pH range of 6.5 to 7.5. Anacharis is a forgiving plant and tolerates a wide range of conditions but does best with moderate sunlight. Anacharis can survive the freezing of surface water, but will not survive in prolonged subzero temperatures. To contextualize the survivability of this plant, one study by the Michigan Department of Agriculture found that anacharis had the potential to establish wild populations over 77.8 percent of the total area of the United States.

How to Plant Anacharis:

Anacharis anchored to the bottom of a pond until its roots establish
Photo by Lamiot, CC BY-SA 4.0, via Wikimedia Commons

If you are able to choose your plant, avoid yellowing, browning, or dark green specimens as their color change indicates they have undergone some form of stress already and may fail to flourish in their new habitat. Additionally, any ties use to bind bunches of plants should be removed immediately—even if not planting right away, to avoid damage to the delicate stems. The ends of the stems may need a 1 to 2cm (less than 0.5 in) trimming if they appear dry, cracked, or damaged.

The easiest way to grow anacharis is to drop them onto the surface of your pond or aquarium. Alternatively, anacharis can survive planting depths up to 4m (13ft). To plant underwater, remove the bottom 2.5cm (1in) of leaves and tuck the plant into the bottom sediment. You should anchor the plants in 2.5-5cm (1-2in) of substrate to prevent them from surfacing. You could also plant them as described in pots and then submerge the pots for faster removal or easier pruning, although this may lead to the roots rotting overtime. Anacharis is not picky in terms of planting medium and can handle just about whatever is currently sitting in the bottom, including aquatic soil, loam, and even aquarium gravel. Individual anacharis plants should be spaced a minimum of 2.5cm (1in) apart to help prevent direct nutrient competition.

How to Care for & Maintain Anacharis:

Anacharis should be watched closely to make sure it does not dominate your pond or aquarium. Regular pruning or pulling of entire plants is suggested, especially if you do not own critters like painted turtles or goldfish to keep the growth in check.

As with other fast growing aquatic plants, overwintering may be more effort than it is worth. However, if you are in an area where your pond may freeze beyond surface ice formation, trim several stems at least 20cm (8in) in length. These clippings can be kept indoors floating or submerged in a tub or aquarium with moderate light (2 watts per gallon for aquariums).

Is Anacharis Toxic, Poisonous or Invasive?

Invasive anacharis that has overtaken the water and needs to be removed
Photo by Lamiot, CC BY-SA 4.0, via Wikimedia Commons

Anacharis is considered illegal or subject to government regulation in a number of states in the U.S. For this reason, you should always check with your local government before purchasing a plant online—especially one as fast growing as anacharis. In 2017, the plant was one of several popular aquarium plants to be banned by the European Union for its invasive potential.

Anacharis is illegal in the following states  –  AL, CT, ID, IL, IN, LA, MA, ME, MI, MS, MT, NE, NH, NY, OH, OR, SC, VT, WA, WI.

Anacharis is believed to be one of the only aquatic plants to establish itself in the Arctic. Wild populations of anacharis have been found in the warmer geothermal waters of northern Iceland since 2013, and springs in southern Iceland since 2003. This is especially concerning given that this jump is over 1000km (about 700mi) from its previously identified extreme habitat range. The finding of invasive aquatic plants in the Arctic is an indicator that anacharis can survive nearly anywhere in the world. Gardeners and aquarium owners should be especially careful when discarding unwanted plants or clippings to safeguard their local waterways.

Will Koi, Goldfish, & Pond Fish Eat Anacharis?

Goldfish love eating elodea plants, anacharis included. Since anacharis is particularly inexpensive and easy to find in most pet stores, it makes an excellent addition to the habitat of these voracious eaters.

Most other fish use anacharis as shelter, although some gardeners have noticed that their gouramis (Osphronemidae family), tetras (Characidae family) and swordtails (Xiphophorus helleri) may snack on them as well. Slider (Trachemys spp.) and Painted (Chrysemys picta) turtles love anacharis, and some pet owners have reported their turtles shredding the anacharis in their tanks at an astonishing rate.

6 thoughts on “Anacharis Facts, Care & Planting Guide (Elodea densa)”

    • Hi DJ,

      I’m sorry for such a delayed reply!

      How large is your pond? For most ponds, about one bunch of anacharis per every 2-3 square feet of surface area is alright. For smaller ponds under 50 square feet, you can plant one bunch of anacharis per every square foot, if desired. It’s a very productive plant, though, so keep in mind that the more you plant, the more you’ll likely have to trim it as it’ll start to grow outward into the pond more as it matures.

  1. I am trying to establish a mini pond (35 gallons) in my backyard and just bought a bunch of anacharis and water lettuce 2 days ago. There are no fish in ther pond currently, but the anacharis has a white tint to it and the water lettuce is starting to get crispy and not soft. Do you have any suggestions or ideas? We are struggling with this little pond and don’t want to give up!

    • Hi Beth,

      Does your pond get a great deal of sun? It sounds to me as though the anacharis and water lettuce are getting sun-burned from too much direct light. You can try a shade sail, as these are pretty cheap, easy to set up, and you can find them online as well as in many stores. For such a small pond, you could also simply set up some form of umbrella or similar structure to help shade part (not all) of the pond – just make sure that whatever you use is anchored so it stays put during storms. Keeping your pond partially shaded will also help to control algae growth, improve oxygen levels, and keep any future fish that you place in the pond more comfortable. You can also try adding in some other floating plants that do well with sun, such as lily pads or lotus. These will help shade any other plants beneath the water’s surface, but do be aware that they grow quickly so you’ll need to trim them back from time to time.

      Hope this helps! I applaud you for seeking out solutions and not giving up on your pond!

  2. I’ve never had any luck with aquatic plant’s till now & the last time I
    got Anacharis it died, that was 3 years ago so I’m going to try it again
    to see if I have any luck this time around, I have other plant’s that’s
    growing good for me like the amazon swords & water Wisteria java
    ferns along with jungle Val, & lotus lilies, in a 75 gal aquarium.

    Is there anything I need to keep in mind with adding the Anacharis
    to the aquarium with the other plant’s I have going right now? B-4
    I put it in the aquarium, which will be in a few days thank you.


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