Helanthium tenellum

Helanthium tenellum, perhaps better known as Echinodorus tenellus is one of the most loved aquarium foreground plants.

Helanthium tenellum

Helanthium tenellum

Helanthium tenellum was described in 1830 by Mart as Alisma tenellum. Afterwards, this well-known plant was given the name Echinodorus tenellus. Due to new descriptions and insights, the name has been changed to Helanthium tenellum, but it will remain known as Echinodorus tenellus for a long time to come… you can no longer change books and this name will also persist on websites and in shops.

Deze soort valt onder de familie Alismataceae or Water plantains.. This family includes about 11 genera and about 90 species. The genus Helanthium has only three species:

  • Helanthium bolivianum
  • Helanthium tenellum
  • Helanthium zombiense


Helanthium tenellum is an aquarium plant that can stay underwater all year round. The leaves are elongated and grow to a maximum length of about 10 centimetres. A leaf is about 3 to 5 millimetres wide. Depending on the amount of light and the variety, the leaf turns green to reddish-brown when there is a lot of light.

Due to the large distribution area, a natural variation has arisen in the color and shape of the leaves. Some varieties become a bit reddish in color under a lot of light. Other variants also remain completely green under a lot of light. In the store, they are often referred to as Helanthium tenellum ‘Green’ (or Echinodorus tenellus ‘Green’).


The distribution area of ​​Helanthium tenellum is very extensive. They occur in the eastern United States from Michigan and Massachusetts south to Florida, to Cuba, Jamaica, along Central America to South America from Guyana to Argentina. It usually grows there as a marsh plant where the roots remain underwater all year round.

The Aquarium

Usually Helanthium tenellum is used as a foreground plant. This plant is also frequently used in aquascapes. The offshoots of the plants run through each other, which gives it a bit of a wild natural appearance.

With regard to the water values, a temperature of 22 to 30 degrees is fine. At a temperature below 22 degrees, the plant hardly grows anymore. Because they can withstand higher temperatures, you can also use this plant in, for example, an aquarium with Discus fish. They tolerate a pH of 6 to 8 but grow best somewhere in the middle.

You can keep Helanthium tenellum without plant food or Co2, but of course, they grow better when they are provided with both. The light doesn’t have to be very bright either. With an average amount of light, the plant grows well. You will see after a while if the plant is not getting enough light. The leaves will then grow towards the light and can grow up to 30 to 50 centimetres in length. Like many other plants, it grows faster with more light, CO2 and plant food. The leaves then remain compact and low.

The roots are a bit tender. It is, therefore, best to keep Helanthium tenellum on sandy soil or opt for very fine (rounded) gravel.


With the right nutrients and amount of light, the plant propagates by forming runners. These runners get new plants at a short distance, after which they sprout further. In this way, a dense mat is formed that continues to expand. They reproduce both completely underwater and along the waterline in a Paludarium in the same way, both with runners.

Helanthium tenellum in a pot

If you bought Helanthium tenellumin in a pot, the roots are often stuck in rock wool. Before you put the plant in the aquarium, remove the pot and the rock wool. Cut the plastic off the jar. Now carefully remove the rock wool. This is easier with a toothpick under running water. Just make sure you don’t rinse the rock wool down the sink to avoid clogging. Trim the roots back to a few centimeters in length if necessary. If the plants are still attached to each other like runners, you can cut them. You can then place the plants wherever you want.


John de Lange

Copyright images

John de Lange



Bijgewerkt op 9 June 2023 door John

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