Elodea canadensis, commonly known as American Elodea or Canadian Pondweed, is a blessing for aquarists and a nightmare for the populations of native aquatic plant species.
Elodea canadensis is a very hardy and adaptable species. It grows extremely fast and rapidly propagates vegetatively. This plant has also an opportunistic nature for obtaining nutrients. In addition, its life cycle favors cool temperatures, and a number of mechanisms that enhance photosynthetic efficiency, which allow it to thrive.
In this article, I will be talking about everything you need to know about Elodea canadensis. This plant profile provides a lot of information about this plant; these include how to plant and care for it in an aquarium.
| Important: Elodea canadensis has been listed as an invasive plant. It exhibits high growth rates with a high tolerance to wide ranges of environmental conditions, low vulnerability to grazing and other stress factors, high distribution and reproduction potential, and relatively high resistance to common conventional aquatic weed management procedures.
This plant is also a major pest in many European, Asian, and African countries. NEVER release it into the wild. The introduction of this plant in a new habitat may bring about dramatic changes in the original, native community. |
Quick Notes about Elodea Canadensis
| Common Name | Elodea canadensis |
| Other Names | American Elodea, Canadian Pondweed, water plague, or Water pest |
| Scientific Name |
Elodea canadensi |
| Difficulty | Easy |
| Lighting | Moderate to high |
| Optimal pH | 6.5 – 9.0 |
| Optimal GH | 2 – 20 |
| Optimal Temperature | 50 – 77°F (10–25°C) |
| Substrate | Any |
| Growth Form | Stem |
| Can Be Grown Emersed |
No |
| Growth Rate | Very fast |
| Placement in Tank |
Background |
| Aquarium size | up to 20 inches (50 cm) |
| Fertilizers |
Needed |
| CO2 | not needed |
| Propagation | Cut stem |
| Color |
Green |
Etymology of Elodea Canadensis
The term “Elodea” is derived from the Greek word ‘Helôdês’, meaning “from the marshes”.
This plant species was described and the name validly published by French botanist André Michaux in 1803.
Distribution of Elodea Canadensis
Elodea canadensis is native to North America and is concentrated around the St Lawrence Valley, the Great Lakes, and the Pacific West Coast.
However, nowadays, this plant can be found all over the world.
Elodea canadensis was introduced to Europe in 1836 (Northern Ireland), and since then is actively spreading over the continent aggressively invading the waterways.
In the 1840s, it was found in Scotland and England, and from 1850 onwards it spread rapidly over the British Isles. In 1850–1860, Elodea canadensis was introduced to Belgium, Germany, and the Netherlands, from where it
spread rapidly to several other central European countries. In 1882, this plant was reported in Russia.
Elodea canadensis is considered a noxious weed in many regions of Asia (China), Africa, Australia, and New Zealand.
Habitat of Elodea Canadensis
Habitat analysis showed that Elodea canadensis prefers habitats with watercourses flowing through the agricultural landscape, with a narrow, more or less disturbed riparian zone.
It is usually found in lakes, ponds, springs, and slowly moving waters in rivers, streams, and canals.
Although some sources say that Elodea canadensis can grow in shallow waters as well as to maximum depths of 42 ft (13 m), results of the experiments showed that the limit for the growth is up to 13 ft (4 m) deep.
This plant does not live in the parts of streams with the most dynamic flow, and extreme water level fluctuations.
Taxonomy problems
Historically there has been lots of confusion in the classification of the species Elodea.
Initially, there were described 17 species. In 1985, according to the latest revision of the genus, there were only 5 recognized species of Elodea:
- Elodea canadensis,
- Elodea potamogeton,
- Elodea bifoliata,
- Elodea nuttallii,
- Elodea callitrichoides
Another problem is that genera Elodea, Egeria, Hydrilla, and Lagarosiphon have been also confused in the scientific literature, mainly because of similarities in appearance and habitat. These plants have all been recorded as weedy, although usually not in their country of origin.
For example, Elodea canadensis is quite similar to Anacharis (Egeria densa) but smaller.
Description of Elodea Canadensis
Elodea canadensis is a perennial aquatic plant species with submerged leaves and floating flowers.
Distinguishing characteristics of Elodea canadensis:
- Plant size: The plant’s height is dependent on the depth of water surrounding it. In the wild, it can attain a massive height of up to 6 ft (2 m). In aquariums, this plant features a height of 10 – 20 inches (20 – 50 cm).
- Structure: Leaves are densely packed along stems. Elodea canadensis has 3 leaves in the whorls and lacks marked leaf serrations. It also feels smooth when handled in the water. The internodes become shorter towards the apex.
- Leaf shape. It is very variable in Elodea canadensis. The leaves can range from ovate to linear-oblong, ovate, and occasionally linear-lanceolate. Leaf apices are broadly acute or obtuse. The angle at the leaf apex is greater than 45º.
- Leaf size. The leaves are relatively short and range from 0.4 to 0.8 inches (1 – 2 cm) and 0.08 – 0.2 (2 – 5 mm) in width.
- Flowers: Elodea Canadensis has also large, attractive white flowers with 3 petals (9-12 mm long) and the presence of ‘double nodes’. Male flowers reach the surface on slender, fragile pedicels. Female flowers are floating and attached.
The flowers of Elodea canadensis are usually borne singly in the axils of leaves and are scattered along the stem in a loose indeterminate inflorescence. The plant is not self-fertile.
In nature, it flowers from May to October, and the seeds ripen from July to October. - Color. The color variation depends on light intensity and/or nutrient status
of the water and/or substrate. Elodea canadensis becomes dark green if does not have enough light and green under optimal conditions. - Growth form. Elodea canadensis can grow only submersed (rotted or floating).
Tank Requirements and Water Parameters
Elodea canadensis is a true survivor. This plant can thrive in a wide range of water parameters. The problem though, it may look leggy if not grown in optimal conditions.
Tank size:
The recommended tank size for growing Elodea canadensis is a minimum of 10 gallons (~40 L).
Because of its growth potential, tall tanks are better than long tanks for this plant. In short tanks, it will reach the top very fast and start trailing along the surface.
Water type, Temperature, Hardness, and pH:
Temperature: Elodea canadensis prefers cool water temperatures between 50 – 77°F (10–25°C). This plant exhibits slow growth even at 40°F (4°C) and is able to survive inside ice for some time.
Note: In nature, this plant overwinters in the mud in the form of swollen shoot apices, and populations are rapidly re-established when these grow out as leafy stems in the spring.
pH: Elodea canadensis can thrive in the range of 6.5 – 9.0 pH.
Hardness: The plant is adaptable to a range of water hardness values (2 – 20 GH). However, it does not like sudden transitions from soft to hard water and vice versa. It may melt.
Lighting:
Elodea canadensis is species is a relatively light-demanding plant.
Bright illumination is required to witness the full growth potential of this plant. Therefore, you should provide medium-high lighting (30 – 50 PAR) using an efficient lighting system.
In addition, maintain a standard photoperiod of at least 8 hours daily (absolute minimum!). Ideally, a 10-hour photoperiod is preferable. Elodea canadensis may melt if it does not get enough light.
When exposed to low lighting conditions, Elodea canadensis becomes dark green and it starts to grow thin and leggy.
Interesting fact: This plant has a high compensation point. For example, it is not photosaturated with light at 3 times the levels tolerated by Anacharis.
Related article:
Substrate:
Elodea canadensis can grow in any (soil, gravel, or sand) substrate. This is a very versatile plant and absorbs nutrients through the root system and from the water column.
Nonetheless, cultivation in enriched substrates will definitely help the plant develop thicker stems and healthy, fleshy foliage.
Some recommended soil substrates for this plant include (links to check the price on Amazon):
Related article:
Flow:
Elodea canadensis does not like high flow. In its natural habitat, this plant is mostly found in slow-flowing or stagnant waters.
CO2 and Fertilization:
CO2: CO2 supplementation is optional.
Fertilization: Elodea Canadensis require moderate to high nutrient levels (especially phosphorus and nitrogen). Experiments showed that although phosphorus can be taken up through the leaves and through the roots, root uptake appears to be the preferential mechanism.
If you do not have nutrient-rich substrate then regular dosing of liquid plant fertilizers (2-3 times a week) is required.
Note: If you keep shrimp in the tank with Elodea Canadensis, I would highly recommend reading my articles:
- CO2 in a Planted Tank Guide
- CO2 in a Shrimp Tank
- How Copper Affects Dwarf Shrimp
- Shrimp Safe Plant Fertilizers
The point is that a high level of CO2 and Copper (most fertilizers contain copper) is extremely dangerous to the shrimp.
Interesting fact: Elodea Canadensis does not react well to Copper sulfate. It significantly slowed or stopped growth even in all concentrations (low: 1 ppm, medium: 5 ppm, high: 10 ppm of copper sulfate) used in the experiments.
Care and Maintenance of Elodea Canadensis
Elodea canadensis is an extremely fast-growing plant. Under optimal conditions (lots of light and nutrition), it can easily grow about 1 inch (2.5 cm) in 1 or 2 days.
As a result, you need to be ready to trim the foliage at least once a week to prevent it from completely overrunning the tank. After trimming, it will shoot out new buds off the sides and can become relatively bushy.
Leafy stems grow upwards to the water surface, followed by lateral shooting and canopy formation. Do not allow Elodea canadensis to reach the surface. You will get a big tangled mass.
Start trimming it when there are 4 – 6 inches (10 – 15 cm) to the surface of the water. You can safely shorten it by half, it will grow back very quickly anyway.
Planting Elodea Canadensis
In aquascaping, Elodea canadensis can be only used to design the background of the tank.
You can use trimmed pieces to replant them. Just stick them into the substrates.
There is one interesting thing about planting this plant. Some Elodea canadensis may rot if you plant them into the substrate. It usually happens when there are no developed roots yet.
To avoid it, some aquarists recommend letting it float in the tank and letting it root by itself.
Tip: If you are planning to start the tank with this plant, do not completely fill it in. Pieces continue to grow while floating in the water. Elodea canadensis will root faster in low water volumes.
Nonetheless, personally, I would not worry too much about rotting. It grows so fast that some of them will survive.
Propagation of Elodea Canadensis
Elodea canadensis is one of the easiest plants to propagate. Simply cut off the stems (3 – 4 inches (7 – 10 cm) long) and plant them.
Stems from regular trimmings can be used for this purpose. You can also remove the leggy stems and replace them with new ones.
In nature, Elodea canadensis colonizes new areas by means of plant fragments with a high survival capacity and through peripheral propagation. In spring, most plant fragments develop propagules, whereas in summer and autumn most fragments anchor themselves to increase survival during winter.
Problems Associated With Elodea Canadensis
Melting: Elodea canadensis usually melt when there is not enough lighting or there are sudden and large changes in water hardness.
Solution: Provide enough lighting and check your water parameters.
Discoloration: Changes in color may be triggered by nutrient deficiency (nitrogen (NO3) and phosphates (PO4)).
Solution: Regular feeding. Use liquid fertilizers periodically. Going forward, always test the tank water and ensure it holds ample nutrients to promote optimal health and development of the plants.
Leggy bottom leaves: When Elodea canadensis gets really large the lower leaves may die back. Top leaves start blocking the light for the lower leaves.
Solution: Prune the plant. Check the lighting. These are usually the main reasons.
Fast growth/ Overgrowth: Under high lighting, nutrition, and CO2, Elodea canadensis can grow like a weed. It can completely fill up the tank within weeks. So, it will require a lot of trimming.
Solution: The plant will require regular stem trimmings to prevent it from overtaking the whole tank.
Related article:
- How to Spot Nutrient Deficiencies in Aquatic Plants
- Everything about Nitrates in Planted Tanks
- Phosphates in Freshwater Tanks
Benefits of Elodea Canadensis
Aquascape: The shape and form of Elodea canadensis can be an excellent decorative addition to the jungle or Dutch style aquascapes.
Oxygenation: Elodea canadensis also generates lots of oxygen in the tank water.
Hiding place: Serves as cover and shade for inverts and small fish.
Foraging place: Acts as a buffet of biofilm, which is an ideal first food for newly hatched fry and shrimplets.
Reduces nitrates: Because of its extensive growing period, Elodea canadensis act as a sink for nutrients such as phosphorus and nitrogen.
Outcompetes algae: Recent studies show that Elodea canadensis reduces the growth of algae and cyanobacteria (allelopathic interactions), it might contribute more to the success of invasive plant species than previously thought.
Related article:
Is Elodea Canadensis a Poisonous Plant?
Well, actually, this is not a myth. The juice of Elodea canadensis can be poisonous to aquatic life (such as fish and shrimp).
I found the experiment describing the toxic effect of Elodea on Daphnia pulex.
To cut the long story short, the juice of Elodea canadensis becomes lethal only in extremely high concentrations (such as 1 gallon of juice (4 liters) per 10 gallons (40 liters) of water)! In all other cases, it is not dangerous either to fish or shrimp.
For more information, check out my article:
Elodea canadensis and Compatible Tankmates
Elodea canadensis should be kept with docile freshwater fish and inverts.
Fish:
The plant is best kept with small, peaceful community fish such as Neon tetras, Killifish, Swordtails, White Mountain Minnows, Zebra Danio, Cherry Barb, Sunburst Platy, Endlers, Mollies, Otocinclus Catfish, Pygmy Cory Catfish, etc.
Shrimp and Snails:
Inverts (freshwater snails or shrimp) are not left out. Elodea canadensis will be great in any shrimp tank.
Avoid or Be Careful
Avoid fish species that may disturb the substrate near the plant or find Elodea canadensis too palatable, e.g. Silver dollars, Bueno Aires tetras, Koi fish, Goldfish, Oscars, Rainbow, Jack Dempsey, Clown loaches, African Cichlids. These species can really cause problems in the planted tanks.
Elodea canadensis and most types of crayfish or freshwater crabs are not a good combination as well. These animals will cut, eat, and uproot everything in the tank. So, keep it in mind and do your research beforehand.
Quarantine Elodea Canadensis
Unless you are completely sure that the plant is safe, for example, it was grown in sterile/laboratory conditions (in vitro) and in vitro pot is not damaged or opened, do not forget to quarantine and disinfect Elodea canadensis to avoid the risk of contamination.
- The plant can have parasites, and hitchhikers like pest snails, or even predators (dragonfly, damsefly nymphs, etc.).
- It could also be treated with chemicals (pesticide) to remove parasites, snails, etc. However, these chemicals are extremely poisonous to fish, shrimp, and other invertebrates.
To find out more, read my articles:
- How to Remove Snails from a Shrimp Tank.
- How to Quarantine and Disinfect Aquarium Plants.
- Pesticides in Shrimp Tanks. Plants Quarantine.
In Conclusion
Elodea canadensis is widely distributed around the world because of its hardy nature and versatility.
This plant is undemanding as regards to maintenance, it also requires minimal care which mainly involves the provision of nutrients and reduction of the plant mass.
If you are in search of a large, fast-growing, and undemanding plant, I would like to let you know that Elodea canadensis ticks all the boxes.
References:
- Bowmer, Kathleen H., S. W. L. Jacobs, and G. R. Sainty. “Identification, biology and management of Elodea canadensis, Hydrocharitaceae.” Journal of aquatic plant management1 (1995): 13-19.
- Zehnsdorf, Andreas, et al. “Management options of invasive Elodea nuttallii and Elodea canadensis.” Limnologica 51 (2015): 110-117.
- Erhard, Daniela, and Elisabeth M. Gross. “Allelopathic activity of Elodea canadensis and Elodea nuttallii against epiphytes and phytoplankton.” Aquatic Botany3 (2006): 203-211.
- Mal, Tarun K., Peter Adorjan, and Andrea L. Corbett. “Effect of copper on growth of an aquatic macrophyte, Elodea canadensis.” Environmental pollution2 (2002): 307-311.
- Eugelink, A. H. “Phosphorus uptake and active growth of Elodea canadensis Michx. and Elodea nuttallii (Planch.) John.” Water Science and Technology 37.3 (1998): 59-65.
- Redekop, Petra, Deborah Hofstra, and Andreas Hussner. “Elodea canadensis shows a higher dispersal capacity via fragmentation than Egeria densa and Lagarosiphon major.” Aquatic Botany 130 (2016): 45-49.
- Wylie, Robert B. “The Morphology of Elodea canadensis. Contributions from the Hull Botanical Laboratory LII.” Botanical Gazette1 (1904): 1-21.
- Heikkinen, Risto, et al. “Predicting distribution patterns and recent northward range shift of an invasive aquatic plant: Elodea canadensis in Europe.” BioRisk 2 (2009): 1-32.
- Kuhar, Urška, Mateja Germ, and Alenka Gaberščik. “Habitat characteristics of an alien species Elodea canadensis in Slovenian watercourses.” Hydrobiologia1 (2010): 205-212.
- Simpson, D. A. “Phenotypic plasticity of Elodea nuttallii (Planch.) H. St John and Elodea canadensis Michx in the British Isles.” Watsonia 17 (1988): 121-132.