Alternanthera aquatica is a fascinating, quite uncommon representative of its genus. It is found along riversides, lakeshores and in swampy areas in Brazil, Paraguay and Bolivia.
This floating plant has a bulky growth and tends to anchor its roots in muddy substrates rich in nutrients. Its shoots grow several metres long and rise above the waterline, providing other floating plants like Limnobium laevigatum, Phyllanthus fluitans, Eichhornia crassipes and Ludwigia helminthorrhiza with a well-protected room to grow.
The internodes of Alternanthera aquatica are filled with air, as adaptation to its life as a floating plant, and look "bloated".
Alternanthera aquatica tries to grow out of even the largest aquarium tanks. Frequently trimming the shoots is thus unavoidable. The cut-off parts may be replanted or can be left floating in the tank, they will form new roots very quickly and resume their enormous growth.
Apart from the large space it requires, A. aquatica is an undemanding plant for a large aquarium. However, if you plan on keeping it in the long run, intensive light is one of the most crucial factors. Ample fertilisation with nitrate, phosphate, potassium and trace elements, via the water or the substrate, speed up growth and provide for lush green stems.
During the warm months, this floating plant may also be kept in garden ponds outside. To provide it with sufficient nutrients, the shoots are best place in a pot with loam or pond soil in the shallow water zone.References and further reading:
Due to its enormous size, this plant is not suitable for just any aquarium. It's seldomly found in the hobby but rather in botanic gardens or ponds in tropical climates.
However, it is very suitable for a South American theme tank, especially if natural habitats in the Pantanal are represented and its diverse floating plant communities, which provide cover for various characin and cichlid species originating from the natural range of distribution of Alternanthera aquatica.1
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