Water velvet (Azolla caroliniana) care guide

Group
Plants
Other names
Azolla cristata (current name), Carolina mosquito fern, Carolina azolla, Mosquito fern
Family
Salviniaceae (floating fern family)
Origin
Eastern North America, Caribbean, Central and South America
Water
freshwater
Maximum size
1 cm
Temperature
5–30°C
pH
6–8
Hardness
Tolerant (estimate)
Care level
beginner
Lighting
Medium to high light; CO2 not needed
Flow
Still water; dislikes surface flow

Care

Legal note: plants sold under this name are often Azolla filiculoides, which may not be sold to buyers in England and Wales (check GOV.UK for the current rules). Wikipedia notes that the type specimen of Azolla caroliniana is in fact A. filiculoides, and that the American plant long called A. caroliniana is now named Azolla cristata. Only a microscope check of the leaf hairs (one-celled in A. filiculoides, two-celled in A. cristata) tells them apart. Azolla cristata, the Carolina mosquito fern, is a tiny floating fern from eastern North America, the Caribbean and Central and South America. Its scale-like fronds are 5–10 mm long, green to reddish (redder in winter and strong light) and look velvety from tiny hairs; mats can be up to 4 cm thick. Like all Azolla it fixes nitrogen through cyanobacteria living in its leaves, and is used as a green manure in Asian rice fields. It survives water at 5 °C in winter and grows best at 25–30 °C in summer, so it suits ponds and tanks alike. Sources: Wikipedia (en.wikipedia.org/wiki/Azollacaroliniana); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.

Breeding

Divides constantly as pieces break off; a few plants soon cover the surface.

Compatibility and tank mates

Goldfish and many larger fish eat it. Covers the surface quickly, cutting light to plants below and gas exchange for fish, so remove a share every week. Floating plants dislike strong surface flow.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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