Frogbit
Limnobium laevigatum
Also sold as South American spongeplant
Synonyms Amazon frogbit · Frog bit · Smooth frogbit · Hydrocharis laevigata
Frogbit (Limnobium laevigatum) is a floating plant for the surface, growing to about 5 cm (2 in) at a fast pace. It wants 64–82°F (18–28°C), low light and no CO₂, and counts as an easy plant to keep alive.
At a glance
| Type | Floating plant |
|---|---|
| Light | LowThe least light it survives in, not the light it looks best in. |
| CO₂ | Not neededWhether it survives without added CO₂ — not whether CO₂ would help it grow faster. |
| Difficulty | Easy |
| Temperature | 64–82°F (18–28°C) |
| Max height | 5 cm (2 in)Grown submersed, left to mature, never trimmed. |
| Growth rate | Fast |
| Placement | floating |
| pH | 6–7.5 |
Before it goes in
- Frogbit lives under a plain low-light LED — it does not need a planted-tank lamp to survive.
- It grows without CO₂.
- It stays around 5 cm (2 in), low enough to keep the front glass clear.
- Its leaves are medium: Goldfish, Electric Yellow Lab and Colombian Ramshorn Snail will eat it.
Can it grow without CO₂?
Yes. Frogbit does not need CO₂ at all.
How much light does it need?
Low light is enough — and that is the survival line, not the “it looks better” line.
How big does it get?
About 5 cm (2 in) tall when it is mature and untrimmed, growing fast, and it does not root at all.
Will my fish eat it?
Its leaves are medium, so some will: Goldfish, Electric Yellow Lab and Colombian Ramshorn Snail.
What it goes with
- Plants that run on the same light and CO₂, so they can share a tank without one of them being the odd one out: Hygrophila corymbosa 'Siamensis', Anubias nana 'Petite', Cryptocoryne wendtii and Hygrophila corymbosa 'Compact'.
- Animals that share its temperature range and will not eat or uproot it: Betta, Cherry Shrimp, Angelfish and Bristlenose Pleco.
Often compared with
| Frogbit | Red Root Floater | Salvinia minima | |
|---|---|---|---|
| Light | Low | Low | Low |
| CO₂ | Not needed | Not needed | Not needed |
| Max height | 5 cm | 2 cm | 2 cm |
| Difficulty | Easy | Easy | Easy |
More plants
Sources (3) · checked Sep 2026
- pHtheplantladysf.com
- pHtheshrimpfarm.com
- Max heighttropica.com