Blyxa japonica
Synonyms Japanese blyxa
Blyxa japonica is a stem plant for the midground, growing to about 15 cm (5.9 in) at a fast pace. It wants 72–82°F (22–28°C), medium light and CO₂ if you have it, and counts as a medium-difficulty plant to keep alive.
At a glance
| Type | Stem plant |
|---|---|
| Light | MediumThe least light it survives in, not the light it looks best in. |
| CO₂ | RecommendedWhether it survives without added CO₂ — not whether CO₂ would help it grow faster. |
| Difficulty | Medium |
| Temperature | 72–82°F (22–28°C) |
| Max height | 15 cm (5.9 in)Grown submersed, left to mature, never trimmed. |
| Growth rate | Fast |
| Placement | planted in the midground |
| pH | 5.5–7 |
Before it goes in
- Blyxa japonica needs medium light. Under a low-light LED it thins out instead of filling in.
- CO₂ is not required, but without it expect slow growth and a thinner result.
- It feeds through its roots, so in plain sand or gravel it needs root tabs; in an aquasoil it does not.
- It only colours up under strong light with CO₂; in a low-tech tank it stays green.
- Its leaves are medium: Goldfish, Electric Yellow Lab and Colombian Ramshorn Snail will eat it.
Can it grow without CO₂?
Yes, but slowly. Blyxa japonica is listed as CO₂-recommended, not CO₂-required: without injection it survives and grows, it just takes far longer to fill in.
How much light does it need?
Medium light — and that is the survival line, not the “it looks better” line. Colour is a separate question: it only turns red under strong light with CO₂.
How big does it get?
About 15 cm (5.9 in) tall when it is mature and untrimmed, growing fast, after roughly 3 weeks to root in.
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: Water Sprite, Anubias nana 'Petite', Cryptocoryne wendtii and Dwarf Hairgrass Mini.
- Animals that share its temperature range and will not eat or uproot it: Betta, Cherry Shrimp, Angelfish and Bristlenose Pleco.
Often compared with
| Blyxa japonica | Gratiola viscidula | Hygrophila corymbosa 'Compact' | |
|---|---|---|---|
| Light | Medium | Medium | Low |
| CO₂ | Recommended | Recommended | Not needed |
| Max height | 15 cm | 15 cm | 15 cm |
| Difficulty | Medium | Medium | Easy |
More plants
Sources (1)
- CO₂dennerleplants.co.ukSep 2026