Salvinia

Quick facts

Max height

3 cm

Growth rate

fast

Difficulty

beginner

Placement

floating

Propagation

fragmentation

Water parameters

Temperature

20–30°C

pH

6.0 to 8.0

Hardness

1 to 20 dGH

Light and nutrients

Lighting

medium

CO2

not needed

Substrate

epiphyte

Feeding

feeds from the water column (use liquid fertilizer)

Substrate

What this plant roots into (or attaches to). The substrate affects both plant nutrition and water chemistry; see each linked page for full effects.

This plant feeds primarily from the water column, so substrate choice matters more for its fish-tank compatibility than for plant nutrition.

With fish

Plant-eating fish

will be eaten by mollies, silver dollars, large goldfish, and other plant-grazers

Diggers (corydoras, loaches)

fine - root system or attachment style handles it

Root-disturbing fish

sensitive to root disturbance, plant where roots stay undisturbed

Habitat

Native to tropical and subtropical regions of the Americas. The genus Salvinia includes several species used in aquariums; the most common is S. minima (water spangles). Salvinia is a floating fern with small, oval, bright green leaves (5–15 mm) arranged in pairs along a branching stem, with a modified third leaf that hangs below the surface as a root-like structure. The upper leaf surface has fine, water-repellent hairs that trap air bubbles, giving the leaves a velvety appearance. Salvinia spreads by fragmentation and budding, forming floating mats on still water surfaces. Several species are invasive in tropical and subtropical waterways worldwide; S. molesta (giant salvinia) is one of the world's worst aquatic weeds. In aquariums, S. minima is the most commonly kept species because of its manageable size (leaves 5–15 mm). Larger species like S. auriculata and the infamous S. molesta produce leaves several centimeters across and are too large for most tanks. S. molesta is one of the world's worst invasive aquatic plants, capable of covering entire lakes and river systems. Do not release any Salvinia species into natural waterways.

Outdoor pond use

This species transitions to outdoor ponds well, not just indoor aquariums.

Outdoor pond zones (USDA)

8 to 13 (winter low around -12°C or warmer)

Below the minimum zone, the plant won't overwinter outdoors but can still be grown seasonally and overwintered indoors. Several pond-friendly species (water hyacinth, water lettuce, parrot's feather) are regulated as noxious in some jurisdictions; check the legality data on the profile before releasing anything to an outdoor body of water.

Care notes

Easy floating plant. Grows under low to high light in any water chemistry (pH 5.5-8.5, GH 2-20+), temperature 15–30°C. Growth rate is fast; a small amount doubles in coverage every 1-2 weeks under good conditions. Thin regularly to prevent complete surface coverage. The tiny leaves and trailing structures provide shelter and grazing surface for fry and shrimp. Salvinia absorbs nutrients from the water column through its hanging root-like leaf, helping reduce nitrate and phosphate. Like all floaters, it needs calm water surface; strong current from filter outlets pushes it around and can damage the delicate leaves. Leave a gap in the tank lid to prevent condensation from dripping onto the leaves (which causes rot). Propagation is automatic through fragmentation and daughter plants. In aquaponics, salvinia is less useful than duckweed for nutrient export because it grows slower, but it's more visually attractive. Compatible with all fish. Available from pet stores, aquatic plant retailers, and hobbyist trades at low cost.

Further reading

• How to cycle a fish tank
• Water chemistry for fishkeepers: pH, GH, KH, and what they mean