Floating fern: the water spangle floater
Salvinia natans
A floating fern of paired, water-repellent leaves — fast shade and cover.
Where it comes from
Salvinia natans is a floating fern found on still fresh water across Europe, Asia and Africa. It has no true roots — instead a modified, feathery underwater leaf hangs beneath the surface pair and does the job of a root.
What to expect
Each plant is a chain of paired oval leaves covered in tiny water-repellent hairs that give them a velvety, silver-green sheen and keep them dry on top. It spreads into a light floating raft, sold under names like water spangles or floating fern.
How to keep it
Like most floaters it is easy given light and calm water. It feeds from the water and pulls nitrate down fast, shading the tank and sheltering fry. Its dislike is surface turbulence, which flips the leaves and wets them.
| Parameter | Value |
|---|---|
| Lighting | Medium to high — compact and dense in bright light |
| CO2 | Not required; draws CO2 from the air |
| Temperature | 18–28 °C |
| pH | 6.0–7.5 |
| Hardness | Soft to hard |
| Fertiliser | Iron and trace elements help |
| Substrate | None — floats |
| Growth rate | Fast |
| Placement | Floating |
| Difficulty | Easy |
Living with it
Give it an open corner and thin it by the handful each week to stop it covering the whole surface. Keep it clear of strong filter flow. A floating corral of airline tubing keeps it where you want it.
What goes wrong
Melting or rotting leaves almost always mean water sitting on top — from a condensation-heavy lid or spray. Leave an air gap and keep the surface calm. Yellowing usually points to a lack of iron. Note it is invasive in warm climates, so never release it.
More plants in this series
- Amazon frogbit (Limnobium laevigatum) — the round-leaved floater
- Water lettuce (Pistia stratiotes) — the big-rooted floater
- Duckweed (Lemna minor) — the tiny relentless floater
- Red root floaters (Phyllanthus fluitans) — the colourful nano floater