Brazilian elodea (Egeria densa), or Anacharis as it’s more commonly known, is an attractive and easy to grow freshwater aquatic plant. It is often confused with the similar looking Canadian waterweed (Elodea canadensis) or hydrilla (Hydrilla verticillata) as it looks very similar.
It is native to South America, and can be found in the waters of Brazil, Argentina and Uruguay. However, due to the aquarium trade, it has become an invasive species in numerous countries worldwide, and can be is highly destructive outside of its natural habitat. It clogs waterways, crowds out native vegetation and can even prevent fish passage. In recent years, it has become established in the United States, Northern Europe, Japan, Australia and New Zealand.
Brazilian elodea grows fully submersed and is a freshwater perennial. It roots in the bottom, though it can also grow free-floating in the water. It is found in everything from lakes and ponds, to small streams and ditches, though it prefers slow-moving, or stagnant water. It can grow in depths of up to 20 feet (6 meters), and its stems grow up to 6 feet (1.82 meters) in length.
Male and female flowers will develop on separate plants, and the flowers are tiny, with white petals that are around 0.75-1 inch (20-25 mm) in diameter, although some are slightly larger. With that being said, the majority of the plants being sold in the aquarium trade are male plants that reproduce vegetatively (through cuttings or fragments).
Even with its incredible popularity in the aquarium trade, some areas now ban its sale or possession due to its invasive potential. Always check local regulations before keeping, or selling this plant.
Caring for Brazilian Elodea
This is an ideal plant for beginners, and can thrive in a variety of conditions. It is very hardy and fast growing, though it does best when provided with moderate to high lighting and nutrient rich waters. It will survive in both cold and warm water, though their nutrient and lighting requirements are significantly higher in tropical aquariums.
It is recommended that you plant Brazilian elodea in gravel like substrate, as it tends to have more difficulty rooting in a loose, sand like substrate. While it can grow free-floating, it needs to be planted to properly mature. Large fish have a habit of uprooting this plant, so it does best with small, relatively docile fish.
Fertilizer should be added to the water column on a weekly basis, and fertilizer root tabs will have little effect, since most of its nutrients are taken from the water column. While it doesn’t require CO2, it will benefit from its addition.
Brazilian elodea should be provided with a minimum of 2 watts per gallon, and the bulbs should provide full spectrum light. A high quality LED bulb, or fluorescent bulbs are the best choices, and unlike many other aquatic plants, it is difficult to provide too much light for this plant.
How to Propagate Brazilian Elodea
It is easily propagated by cuttings, and a cutting from the main stem will quickly grow into an adult plant. Cuttings should only be taken from mature and healthy plants.
Where to Place Brazilian Elodea
Brazilian elodea looks best when it is placed in the background of an aquarium. Regular trimming may be required to prevent it from over growing and looking unkempt, and if it is left to its own devices, it will completely choke off an aquarium.
How to Tell Brazilian Elodea and Canadian Waterweed Apart
Brazilian elodea (Egeria densa) is often confused with Canadian waterweed (Elodea canadensis), as they look nearly identical. However, Brazilian elodea has four leaves per whorl and each leaf is usually around 0.75 inches (2 cm) in length. Canadian waterweed only has three leaves per whorl, and they are generally shorter, at only 0.40 inches (1 cm) in length.