Salvinia natans

Also known as Floating fern, Floating watermoss, Floating moss

FreshwaterFloatingFragmentationSide shoots

Invasive. Salvinia species are regulated as noxious weeds in some areas. Never release into the wild; dispose of in the trash.

Salvinia natans (Salvinia natans) — Le.Loup.Gris · CC BY-SA 3.0

Care at a glance

Light: Medium light
CO2: No CO₂ needed
Temperature: 64–82°F; 18–28°C
Max height: 1.2 in; 3 cm

Growth rate: Fast
Placement: Floating
Type: Floating
pH: 6.0–8.0
Hardness: 2–15 dGH
Spread: 3.9 in (10 cm)
Nutrient uptake: Water column
Growth region: Submersed or emersed
Difficulty: Beginner
Family: Salviniaceae
Origin: Central/Eastern Europe and Asia

Overview

Salvinia natans is a fast-growing floating fern that sits on the surface and shades the tank below. It is a beginner plant, and it stays low and small, unlike taller floaters.

Did you know

Most plants sold as Salvinia natans are a different fern, since the true species is rarely sold. Shops usually offer a giant salvinia from the Salvinia auriculata group under this name. That plant grows bigger and folds its ruffled leaves upright, while the real one keeps small, flat, oval leaves.

Caring for Salvinia natans

Float Salvinia natans on calm water with a bright light overhead. Heavy surface agitation and condensation dripping from above both rot the floating leaves.

It grows fast in medium light with no CO2 and no substrate. It pulls its nutrients straight from the water column, which helps starve out algae, so feed it with a liquid fertilizer rather than root tabs. In very low light it turns pale and stringy.

It branches and divides on its own, and pieces that break off keep growing. Keep it going simply by removing the excess. The same care suits the giant salvinia usually sold under this name.

Good to know

Salvinia natans is a true floating fern in the family Salviniaceae, and it has no roots. What looks like a pair of leaves and a hanging root is really three leaves per node. Two oval leaves float on the surface, and a finely divided third leaf dangles below and does the job of a root. Tiny water-repellent hairs on the floating leaves trap a film of air and keep the plant from getting waterlogged. The hairs stand in groups of four with free tips, while giant salvinias join theirs at the tip like a whisk.

In the wild

Salvinia natans is native to standing and slow fresh water across central and eastern Europe and much of temperate to subtropical Asia. It grows in ponds, ditches, lakes and quiet river edges with still water, plenty of sunlight and humid air. Unlike most aquarium floaters, it is an annual that dies back in cold weather and overwinters as spores.

Common questions

Does Salvinia natans need to be planted in the substrate?

No. Salvinia natans floats at the surface and takes its nutrients straight from the water.

Does Salvinia natans need CO2?

No. Salvinia natans grows well without added CO2.

How much light does Salvinia natans need?

Salvinia natans wants medium light. A light sold for planted tanks covers it.

How do you propagate Salvinia natans?

Salvinia natans propagates by fragmentation and side shoots. Pieces that break off keep growing, so pulling a clump apart spreads it. Side shoots bud off and float free.