Floating water sprite

Care at a glance

Overview

Let it float for the fastest growth and the best plantlet production, or anchor the base loosely in substrate for a taller submersed form. It is undemanding, thriving across a wide range of conditions in low-tech and even unheated setups with no CO2 needed, though bright light keeps it compact and green instead of stringy. Because it grows fast it soaks up excess nutrients and shades the tank, so plan to thin it often, and pull the baby plants (plantlets) that sprout along the older fronds to start new plants.

In the wild

Ceratopteris cornuta is a floating and marsh fern of the Old World tropics, found through tropical Africa and Asia in shallow ponds, ditches, rice paddies and slow backwaters. It grows either free-floating with a rosette of coarse, lobed fronds and a curtain of roots hanging below, or rooted in mud at the water's edge. It is naturally adapted to warm, still, nutrient-rich shallow water.

Good to know

It is a true aquatic fern in the family Pteridaceae (older aquarium references still use Parkeriaceae or Ceratopteridaceae for the water sprites). Its taxonomy is genuinely muddled: many botanists treat C. cornuta as a synonym or coarse-leaved form of the widespread C. thalictroides, and in the hobby the coarser broad lobes are what get sold as cornuta. Like all ferns it can complete a full spore life cycle, but in tanks it almost always spreads vegetatively instead.

Did you know

Water sprite is such an efficient nutrient sponge that fishkeepers deliberately float a clump in new or algae-prone tanks to outcompete algae, and shrimp and fry treat its dangling roots as a built-in nursery.

Related plants

• 

  Water sprite

  Ceratopteris thalictroides

  Medium lightBackground15 in (38 cm)

• 

  African water fern

  Bolbitis heudelotii

  Low lightEpiphyte15.7 in (40 cm)