Large algae fern - Azolla filiculoides - Portion - Dennerle

The large algae fern or floating fern Azolla filiculoides originally comes from North and South America, but is now found worldwide and can even partially overwinter outdoors in Germany. It is therefore not only suitable as a floating plant for the aquarium, but can also be cultivated in the pond. Here, however, it should be overwintered frost-free in any case - better safe than sorry.

As a floating plant, Azolla filiculoides is an excellent nutrient consumer, as its growth is not limited by the CO2 in the water. It is therefore very suitable for preventive use against algae plagues, but also just looks pretty as it is. With shy fish and also shrimps, you can quickly shade the aquarium a little with the algae fern and thus give the animals a feeling of homeliness. In the fine root beards young fish and baby shrimps find excellent hiding places.

To propagate, simply divide the shoots of Azolla filiculoides. Nutrients can be easily removed from the aquarium or pond by cutting off part of the algae fern plants. The floating fern forms a symbiosis with a cyanobacterium and stores an unusually high amount of nitrate.