Ceratopteris thalictroides is a fern species more commonly known as water sprite and belongs to the Pteridaceae family. Other names that are often used are water fern or Indian water fern. The genus Ceratopteris is derived from “keratos” which means “horn” and “pteris” meaning “fern” in Greek. In 1821 there were a total of 11 different species within the Ceratopteris genus, however, in 1974 Robert M Lloyd published a monograph that grouped these eleven into 4.
This beautiful plant can be found in most tropical regions globally, due to its ability to withstand a wide variety of conditions. Water sprite is an amphibious plant, meaning it can survive both in and out of water. Therefore, not only is this plant perfect for aquariums but it can also be introduced to a paludarium.
Water sprite has beautifully vibrant green stems with fingerlike projections as leaves, similar to their terrestrial relatives, the fern. This stunning appearance makes water sprite very popular for aquariums. Many benefits can come from introducing water sprite into your ecosystems, such as quick growth and high photosynthesis rates, releasing large amounts of oxygen.
Water sprite can also keep stagnant water bodies clean and absorb lots of nitrates which prevents a buildup of algae.
Water Sprite Growth, Hardiness & Climate
Water sprite is well known for its quick growth rate, reaching a maximum size of around 70cm when planted, although the average size is between 30-60cm. When floating, this plant can grow to cover the entire water surface depending on the aquarium size. So, it is very important to keep control of the water sprite’s growth through frequent trimming.
As water sprite is pan-tropical, it is found in most tropical areas in both hemispheres! You might be wondering how water sprite can survive in such a wide range of habitats, and this is due to its excellent versatility and high survival rates. Water sprite can withstand hardiness zones between 9-11 USDA, and is most commonly found in stagnant water bodies such as swamps and marshes, making it perfect for aquariums and manmade ponds.
How to Plant Water Sprite
So, how do we plant this beautiful species? As previously stated, one main attraction of water sprite is that it can either be planted or float on the water surface. Floating water sprite can add lovely texture and depth to your aquarium or pond, whereas planted water sprite can create a dense background.
If you choose to plant your water sprite, first start with 2 – 3 inches of a substrate of your choice along the bottom. Create a small hole in the substrate, then place the plant into it. Make sure to cover the roots completely, but not too deeply, as this can lead to rotting. Fill the hole back up with substrate to secure the submerged plant.
Due to water sprite’s hardiness and the fact that they mainly feed through their leaves, any substrate will satisfy this plant. However, in an aquarium, it is best to have a nutrient-rich substrate to ensure the plant can uptake all the nutrients it requires.
Water sprite is great for reproduction, as you can simply take a clipping from the mother plant and either replant it in a substrate or let it float. Water sprite can easily survive while floating, and adds beautiful color to the water surface as well as adding depth. You can drop cuttings onto the surface of the water and then allow them a couple of days to grow roots, which will fall slightly below them. The floating water sprite absorbs the necessary nutrients directly from the water. Another benefit of having floating water sprite in an aquarium is that the leaves will grow larger due to being closer to the source of light, increasing the rate of photosynthesis.
How to Care For Water Sprite
Water sprite prefers low to moderate light conditions, so it would be ideal to place them between the middle to the back of a fish tank or pond. Another benefit of this placement is that this plant will grow upwards at first, therefore avoiding the delicate leaves from becoming damaged by the power filter.
Besides beauty, another attractive quality of this plant is that it does not require too much attention, making it exceptionally easy to care for. The only attention it requires is maintaining its size. When in optimum conditions, there is no limiting factor to growth, allowing water sprite to grow very quickly. To keep on top of this, it needs to be trimmed regularly.
When trimming the water sprite, avoid cutting the main stem as this will cause damage to the plant. The snippets obtained from maintenance are perfect for replanting or allowing to float on the surface.
Water sprite has an optimum soil pH between 5 and 9 which is a very wide range due to water sprite being very tolerable to different conditions. To prevent damage to your water sprite, keep the soil pH around neutral or slightly acidic. The wider pH range between 5-9 is very beneficial within larger ecosystems in ponds and aquariums, as you can monitor and maintain a pH close to optimum for a wider range of species.
How to Winter Water Sprite
Water sprite is hardy to cold weather and will quickly die back during the first frost of the year. To overwinter, you can bring a few small plants indoors to a small aquarium or aerated container (i.e., with use of an air stone bubbler) to keep them healthy. Since water sprite grows so quickly in the right conditions, allowing most of the plants to die back in winter and only re-planting the few smaller plants you kept indoors will help keep it’s annual growth under control.
Is Water Sprite Invasive or Toxic?
Indian water fern is another common name for this plant, as this species was originally contained within Central and Southern India. Water sprite can therefore be seen as invasive, as it is now pan-tropical. Water sprites are not toxic, but instead are beneficial to other fish and plants in the ecosystem. One attraction of the water sprite is that it can create shade beneficial for shy fish, for example, Cherry Barbs. Their rapid growth and photosynthesis release lots of oxygen and prevent algal growth, ensuring a healthy water body, sustaining the life of beautiful plants and organisms.
Where to Buy Water Sprite & Seeds? (UK & US)
You can find water sprite at most local aquarium stores or easily purchase it online. Remember that water sprite has other common names, so it might be sold as ‘Indian water fern’ or ‘Water fern’.
Make sure you are purchasing a healthy plant to prevent the disappointment of this species browning or dying shortly after being planted. It is easy to identify sick water sprites due to holes or tears in their leaves, so be sure to inspect the condition of the plant before purchasing. The roots of this species when planted should be very large and numerous, which also indicates it is in good health.
