Photo: Forest and Kim Starr / CC BY 3.0 usWater Sprite Care
Ceratopteris thalictroides · Pteridaceae
🐾 Pet-safe
🎯 Easy
☀️ Medium, bright indirect
💧 Every 7 days
Photo: Forest and Kim Starr / CC BY 3.0 usCare at a glance
Light
Medium, bright indirect
Temperature
22–28 °C (72–82 °F)
Soil
a nutrient-rich aquarium substrate (or attached to wood/rock)
Difficulty
Easy
Mature size
15–40 cm (6–16 in)
Pet safety
Pet-safe
Care effort
Medium
The short version
- Beginner-friendly and forgiving.
- Give it Medium, bright indirect.
- Water every 7–7 days.
- Safe around cats and dogs.
The Water Sprite (Ceratopteris thalictroides) is an aquatic plant grown submerged in freshwater aquariums. It comes from Pantropical and is rated Easy to keep, reaching 15–40 cm. Here is how to grow it underwater — lighting, substrate, CO₂, placement and propagation.
Also known asCeratopteris thalictroidesウォータースプライト水蕨Helecho acuáticoFougère de Sumatra
📋Quick facts
| Growth rate | Fast |
|---|---|
| Mature size | 15–40 cm (6–16 in) |
| Native region | Pantropical |
| Plant family | Pteridaceae |
| Toxicity | Non-toxic |
| Air-purifying | No |
| Ideal for | beginners, homes with pets |
⚖️Pros & cons
Pros
- Non-toxic to cats and dogs
- Hard to kill; great for beginners
- Fast, rewarding growth
- Compact — fits a desk or shelf
Cons
- Needs high humidity to look its best
🐟Growing it in an aquarium
Keep the water at 22–28 °C. Stable, gently moving water and regular partial water changes keep it healthy; sudden swings in temperature or chemistry cause melting.
Light
Give it Medium, bright indirect-equivalent aquarium lighting. Low-tech tanks suit undemanding species; brighter light (and often CO₂) brings out the best colour and compact growth but also feeds algae, so balance it carefully.
Soil
Plant it in a nutrient-rich aquarium substrate (or attached to wood/rock). Rooted species are hungry feeders — use root tabs or a liquid aquarium fertiliser (and CO₂ for demanding types). Epiphytes like Anubias, Java fern and Bucephalandra must NOT be buried: tie or glue their rhizome to wood or rock, or they rot.
Its size and habit suit a spot in the foreground, midground or background depending on how tall it grows; trim and replant tops to keep it dense.
✂️How to propagate, step by step
Spring and early summer, during active growth, give the best success. Here is how to do it, step by step:
plantlets (runners)
- Look for baby plantlets forming on the runners or stems.
- Leave them attached and rest each one on a small pot of moist mix.
- Once it roots into the pot (a couple of weeks), snip it free from the runner.
- Or cut a well-formed plantlet and root it in water first, then pot it up.
- Grow the young plant on in bright, indirect light.
spores from mature fronds
🔬Classification
| Plant type | Aquatic plant |
|---|---|
| Genus | Ceratopteris |
| Family | Pteridaceae · Pteridaceae |
| Native to | Pantropical |
🩺Common problems
| Symptom | Likely cause | What to do |
|---|---|---|
| Algae on leaves or glass | Too much light or excess nutrients in the water | Cut the lighting period, reduce feeding, and add algae-eating clean-up crew. |
| Melting or dissolving leaves | Shock from a new tank (common when settling in) | Be patient — trim mushy leaves; new submerged growth usually follows. |
| Yellowing leaves | Usually overwatering or poor drainage | Let the soil dry more between waterings and make sure the pot drains. |
🐛Pests & prevention
The usual indoor pests are spider mites (fine webbing, speckled leaves), mealybugs (white cotton-wool tufts), scale (small brown bumps), and fungus gnats (tiny flies from soggy soil). Inspect any new plant before it joins the others, wipe the leaves now and then, and let the topsoil dry to keep gnats away. At the first sign, isolate the plant, wipe or rinse off what you can, and treat with insecticidal soap or neem oil every week until it is clear.
🐾Is it safe for pets?
Good news for pet owners: the Water Sprite is considered non-toxic to both cats and dogs by the ASPCA. It is one of the safer choices for homes with animals, though eating any plant can still cause mild stomach upset.
Toxicity information is a general guide based on ASPCA data. If your pet or child may have eaten any part of a plant, contact a vet or poison control right away.
❓Frequently asked questions
Is the Water Sprite toxic to cats and dogs?
No — the ASPCA lists the Water Sprite as non-toxic to cats and dogs. Eating a lot of any plant can still cause mild stomach upset.
How often should I water a Water Sprite?
About every 7–7 days — let the top few centimetres of soil dry out first, then water thoroughly and drain.
How much light does a Water Sprite need?
Medium, bright indirect. Keep it out of harsh direct midday sun unless it is a full-sun plant.
Why does my Water Sprite have Algae on leaves or glass?
Too much light or excess nutrients in the water. Cut the lighting period, reduce feeding, and add algae-eating clean-up crew.
How often should I repot a Water Sprite?
About every 1–2 years, ideally in spring. Move up just one pot size when the roots fill the pot or creep out of the drainage holes.
How fast does a Water Sprite grow?
It is a Fast grower, with most of its growth in the brighter, warmer months of spring and summer.
How big does a Water Sprite get indoors?
Usually 15–40 cm indoors, depending on light, pot size, and how long you have had it.
Is the Water Sprite an air-purifying plant?
It is grown mainly for its looks rather than as an air-purifying plant, though all houseplants add a little greenery and humidity.
Is the Water Sprite easy to care for?
It is rated easy. It is very forgiving and great for beginners.
📚Sources & further reading
Care values reflect established horticultural guidance; toxicity is cross-referenced with the ASPCA.
🌱Related plants
Anubias Barteri
Anubias barteri
Anubias Nana Petite
Anubias barteri var. nana 'Petite'
Java Fern
Microsorum pteropus
Amazon Sword
Echinodorus grisebachii
Cryptocoryne Wendtii
Cryptocoryne wendtii
Vallisneria
Vallisneria spiralis
Last reviewed: 2026-08-23