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Family: Alismataceae

Common Name: Red Melon Sword

Origin: This is a cultivar species and consequently has no natural distribution.

Ideal position in aquarium

A specimen plant, suitable for the mid-ground in most tanks except very small aquaria, or back-ground in shallower tanks.

Lighting requirements

Moderate to bright. This cultivar grows very well in moderate light, better than many red-leaf plants, but the red will be much more intense with brighter lighting. In less light, the leaves will initially appear as brownish-red but turn more olive green as they mature.

Growth rate


Minimum Tank Suggestion

20 gallon but preferably larger.

Water parameters for Red Melon Sword

Soft to medium hard, slightly acidic to slightly basic water, temperature 18-26C/64-79F.


This red-leaf sword cultivar was one of the first to be developed, but its adaptability to varying water parameters and moderate lighting have kept it popular as a nice contrast plant in aquaria. It is sometimes seen under the common name of "Osiris Double Red" as well as "Red Melon" Sword.

The leaves are very similar to those of Echinodorus osiris [see that species profile] except for being red/brownish-red in colour and somewhat wider when grown in the same aquarium. In growth it will attain 10-20cm/4-8 inches in height with a spread of up to 25cm/10 inches. Several authors indicate a significantly larger plant, so either this is based on higher nutrients/lighting or it may be another variety. The writer (Byron) has maintained this plant for two years within the stated dimensions which are taken from Kasselmann (2003).

The leaf colour is largely dependent upon light and nutrient supply. In one of the writer's aquaria with plain fine gravel substrate, regular liquid fertilization and moderate lighting, the leaves tended to be brownish/olive green. With a more nutritious substrate, the leaves are more reddish/brown. Other writers report that in brighter light, a nutritious substrate and with CO2 diffusion, the leaves will be a more intense shade of red/reddish-brown.

Like the parent plants, this species can be grown emersed (as in a plaudarium) or submersed. In the aquarium, it will produce inflorescences with adventitious plants. Flowers will appear on the inflorescence when the plant is grown emersed.

In 1986, H. Muhlberg described this plant as a distinct species, Echinodorus barthii, the epithet honouring the plant breeder H. Barth. Kasselmann (2003) and most other writers believe it is a hybrid and not a distinct species. Echinodorus uruguayensis is said to have been one of the parent species, and the other is probably E. osiris whose distinctive submersed leaf shape and veining is very prominent in this hybrid.

Some of the most beautiful and useful plants for the tropical aquarium are found among the Echinodorus, a genus distributed in the tropical and sub-tropical regions of the Americas from the lower United States down to Argentina; the two "African" species of Rataj are almost certainly erroneous (Kasselmann, 2003). The genus name derives from the Greek echinos [hedgehog] and doros [pipe or hose] referring to the spiny fruit. The English common name "sword plant" comes from the general lanceolate shape of the leaf of most species and is generally used for all plants in this genus although other non-Echinodorus plants may sometimes appear under the name "sword."


Kasselmann, Christel (2003), Aquarium Plants, English translation, Krieger Publishing Company.

Muhlberg, H. (1986), "Echinodorus barthii spec. nov." Aquarien Terrarien 33(11), pp. 368-369.

Contributing Members

The following members have contributed to this profile: Byron


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