Water sprite
Ceratopteris thalictroides
Also known asIndian fern · Water fern · Floating fern
Water parameters
Light and nutrients
Substrate type: any. Propagation: daughter plants.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Bare bottom (no substrate) (Bare bottom) | n/a | none |
| Inert sand (Pool filter sand) | neutral / inert | none |
| Inert gravel (Aquarium gravel) | neutral / inert | none |
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
With fish
Origin and habitat
Native to tropical and subtropical regions across Asia, Africa, and the Americas. The species (Ceratopteris thalictroides) is an aquatic fern with finely divided, bright green fronds that grow either rooted in substrate or floating on the surface. The fronds are deeply lobed and lacy, creating a feathery, open texture. Water sprite is one of the fastest-growing aquarium plants and one of the most effective nutrient sponges, pulling nitrate and phosphate from the water at a rate comparable to floating plants. The plant has been a staple of the aquarium hobby for decades, valued for its versatility, fast growth, and use as a natural water purifier in newly cycling and overstocked tanks. The species name 'thalictroides' means resembling Thalictrum (meadow rue), referring to the finely divided frond shape. Water sprite is one of the few amphibious aquarium ferns, growing equally well submerged, emergent, or floating. The terrestrial form (C. cornuta) is sometimes sold separately but is the same species in a different growth phase. Widely distributed across tropical latitudes and naturalized in warm regions worldwide.
Care notes
Extremely easy. Grows in any light (moderate to high produces the fastest, most robust growth), any water chemistry (pH 6.0-8.0, soft to hard), temperature 20–30°C, and without CO2. Can be planted in substrate (where it develops a root system and grows upright) or left floating (where it grows larger and more rapidly, with fronds spreading across the surface). Floating water sprite produces adventitious plantlets on the frond margins; small plants form directly on the older fronds and detach naturally, each growing into a new plant. This prolific reproduction means a few sprigs quickly become a tank full. Trim aggressively and discard excess; the plant doubles in mass every 1-2 weeks under good conditions. The fast growth makes it one of the best plants for competing with algae in new tanks. The lacy fronds provide excellent cover for fry and egg-laying fish. Betta keepers often use floating water sprite as a bubble nest anchor. Available from pet stores and hobbyist trades at low cost. A foundational plant for any fishkeeper.