Fairy moss
Azolla filiculoides
Also known as Water fern, Mosquito fern, Red azolla, Pacific azolla
Care at a glance
- Light
- Medium light
- CO2
- No CO₂ needed
- Growth rate
- Fast
- Placement
- Floating
- Type
- Floating
- Temperature
- 59–82°F (15–28°C)
- pH
- 6.0–7.5
- Hardness
- 2–18 dGH
- Max height
- 0.8 in (2 cm)
- Spread
- 11.8 in (30 cm)
- Nutrient uptake
- Water column
- Growth region
- Submersed or emersed
- Difficulty
- Easy
- Origin
- A tiny floating fern native to warm and temperate fresh water across the Americas, now naturalized widely on ponds, ditches, and still backwaters.
- Family
- Salviniaceae
Overview
Drop it on the surface in moderate light and it will spread quickly with no CO2 or planting needed. It dislikes strong surface agitation, so calm water and a gentle filter outflow suit it best, and weekly scooping keeps it from covering the whole top. It draws nutrients straight from the water, which helps starve out algae.
In the wild
Azolla is a minute floating fern whose overlapping scale like leaves form a soft green film across the water surface. Under strong light or cool weather the mat turns deep red, giving it real ornamental appeal. It multiplies fast and provides shade and cover for fry and shrimp at the surface.
Good to know
Azolla is a true fern, not a flowering plant, and it spreads by spores and by simply breaking apart. Each frond houses the nitrogen fixing cyanobacterium Anabaena azollae in a small leaf cavity, a partnership carried from one plant generation to the next.
Did you know
Because its cyanobacterium pulls nitrogen from the air, Azolla has been grown for centuries as a natural fertilizer in flooded rice paddies, and it is banned from sale as an invasive weed in parts of Europe.
Where to buy
Some links may not be the exact species or variety.
- Glass Aqua Aquascaping plants and planted tank supplies
- Aquarium Plants Factory Aquatic plants shipped from a California greenhouse
…or ask your local fish store.
Appears in
No-CO2 plants · Floating plants · Beginner plants · Fast growers
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