Dwarf hygrophila
Hygrophila polysperma
Also known asIndian swampweed · Dwarf hygro · Miramar weed
Water parameters
Light and nutrients
Substrate type: inert ok. Propagation: stem cuttings.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Inert sand (Pool filter sand) | neutral / inert | none |
| Inert gravel (Aquarium gravel) | neutral / inert | none |
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
With fish
Origin and habitat
A small-leaved stem plant of the acanthus family, Acanthaceae, Hygrophila polysperma, called dwarf hygro, Indian swampweed or Miramar weed. It is native to Bangladesh, India, China and Malaysia, in marshes, ditches, rice paddies and slow waterways, with opposite pairs of oval to lance-shaped leaves 2–4 cm long on a thin upright stem. Submerged leaves are light green, flushing pink toward the tips under strong light, and the Tropica cultivar 'Rosanervig' carries white-to-pink veining. It is one of the fastest-growing aquarium plants, which makes it both a great beginner plant and a serious invasive: it forms dense monocultures that crowd out native plants thanks to its low light needs and rapid growth. As a result it is a US federal noxious weed and on the EU list of invasive alien species, and it has naturalised in Florida, Texas and beyond.
Outdoor pond use
- USDA zones
- 8–13 (winter low around -12°C or warmer)
Care notes
Extremely easy and nearly unkillable. It grows in anything, low to high light, no CO2, almost any water chemistry and a wide temperature range, and it is a heavy feeder that grows fastest with a nutrient-rich substrate. Growth is fast to explosive, often needing trimming two or three times a week in a bright tank, which makes it one of the best nutrient-export plants for soaking up nitrate and phosphate and outcompeting algae in a new tank. Plant stems in groups, trim the tops and replant the cuttings, and the cut lower stems throw multiple side shoots so it gets bushier with each trim. The 'Rosanervig' form shows the prettiest pink-white veins under strong light. The catch is legal: in the United States it is a federal noxious weed, illegal to import, sell or move across state lines, and prohibited in Florida; across the European Union it is on the Union list of invasive alien species, added in 2017, which bars keeping, breeding, sale and release. Where it is legal it is one of the most useful starter plants, but never release it or dump tank water outdoors.