About animals

Azolla Carolina (Azolla caroliniana)


  • Other names: Azolla caroliniana.
  • Origin: North America.
  • Size: height 0.5-2 cm, width.
  • Temperature: 20–28 ° C.
  • Water parameters: pH.
  • Lighting: 0.8-1 W / l.
  • Growth rate: medium.
  • Additional information: grows on the surface of the water.
  • The complexity of the content: complex.


A small floating fern with blue-green algae growing on its leaves, capable of absorbing nitrogen from the air, which in turn is used by the plant. Water resistant. Currently, this plant has spread throughout the tropics, and has become an environmental threat, as it draws the entire surface of the lakes and deprives the light of plants growing at the bottom.

Azolla Caroline is widespread in both tropical and subtropical regions. This fern forms very beautiful green islands floating on the surface of the water. The plant is very tender, requires careful handling. It is relatively rare among aquarists. It has a pronounced seasonal pattern of growth with a dormant period in winter.


The plant requires a very bright light. For artificial lighting, you can use fluorescent lamps such as LB and incandescent lamps. Incandescent lamps should be used with caution, as too bright light from them can burn floating parts of the plant. The power of fluorescent lamps should be at least 0.8-1 W / l. Duration of daylight hours is at least 12 hours. Under favorable conditions, the azolla, rapidly growing, draws on the entire surface of the aquarium, obscuring other plants, so its excess must be periodically removed from the aquarium.


The dying of the azolla in the winter period is usually associated with a decrease in illumination, therefore, under very bright lighting and a sufficiently high temperature of the water, the plant can be preserved.

Also for the winter, you can extract the Caroline azolla from the aquarium and place it in a container with wet swamp moss. In such conditions, at a temperature of 12 ° C, the plant has a great winter, and by March it can already be released into the aquarium again.


In the aquarium, Azolla Carolina is suitable for creating natural shading, as well as for providing shelter to growing young fish. In a closed aquarium, the maintenance is problematic, but in open aquariums with a large surface area, the thickets of this plant are great for decorating the water surface.

Water Fern, Magic Moss, Mosquito Fern

Family Salviniaceae
Floating plant

tropical and subtropical zone of America

  • small aquatic fern, whose vaii resemble moss,
  • forms a low cover on the water surface (0.7-2.5 cm high),
  • the stem is horizontal, forked, with a bunch of hanging roots, with a low level of water rooting in the ground

neutral or slightly acidic

keep in the aquarium, observing the following conditions:

  • temperature + 20 + 28 degrees (at +16 and below, the plant rots and plunges into water, where the spores remain until spring),
  • Illumination is not lower than 2-2.5 W per 1 sq. dm, length of daylight 12 hours (dies away with a short daylight)

another way of preservation is to put it in a moist sphagnum and keep it at a temperature of up to +12 degrees

filling the surface of the reservoir with azolla may cause shading of submerged plants

during the season, part of the plants is removed with a net to restrain spread

Origin and description

Azolla Carolina is a native of North America, lives in the eastern and southern regions of the United States, as well as in Central and South America. In nature, mosquito fern is found on the surface of ponds, lakes and swamps, forms a dense thick coating on the surface of the water (mats). Azolla, depending on the light intensity, can be green, red or saturated red. The leaves are scaly, 5-10 mm long, covered with thin hairs that give a resemblance to velvet. Due to the too rapid growth of this fern, azolla is rarely used as an aquarium plant, however, it can always be found on sale in both amateurs and nurseries.

In nature, Caroline azolla comes into symbiosis with the blue-green alga Anabaena, growing in cavities at the base of fern leaves. The Anabaena algae is able to receive nitrogen from the air, and makes it available to its host plant. Therefore, due to its high nitrogen content, Carolina azolla is often grown in rice fields and is often used as agricultural nitrogen fertilizer.

Due to its propensity for invasive distribution, Azolla Caroline cannot be used in open local water bodies.