Pygmy chain sword
Helanthium tenellum
Also known asNarrow-leaf chain sword · Dwarf chain sword · Echinodorus tenellus (synonym)
Water parameters
Light and nutrients
Substrate type: nutrient preferred. Propagation: runners.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| 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 |
| Inert sand (Pool filter sand) | neutral / inert | none |
With fish
Origin and habitat
A small grass-like sword of the family Alismataceae, long known as Echinodorus tenellus and now reclassified as Helanthium tenellum. It is native widely across the Americas, through the eastern United States from Texas and Florida north to Michigan and Massachusetts, southern Mexico, the West Indies, Central America and South America to Argentina, in shallow pond margins, seasonal wet meadows and freshwater flats. The smallest of the swords, it forms grass-like rosettes only 3–7 cm tall and spreads by runner chains, like dwarf sagittaria, into dense carpets of narrow leaves a millimetre or two wide. A green standard form and a red or bronze form are traded, the latter colouring up under strong light.
Care notes
An easy carpeting plant that works in both low-tech and high-tech tanks. It is undemanding, growing in low to medium light with no CO2, where it stays sparser and a bit taller, and under bright light with CO2 and fertiliser it forms a fast, dense turf and stays short. The red or 'bronze' form needs moderate to high light and good iron to colour; in low light it stays green. Plant small portions a couple of centimetres apart, and a nutrient-rich or soil-based substrate, or root tabs, drives faster, denser growth, since it has an extensive but delicate root system. It propagates itself by runner chains up to half a metre long that bud plantlets every few centimetres; detach and replant them gently. Trim the top to hold height. It likes soft to moderately hard water around pH 6 to 7.5 and a wide temperature range, and is cold-hardy given its temperate distribution. It is shorter than dwarf sagittaria under good light and offers a red form, at the cost of slightly higher light needs; the two combine well for a varied low-tech ground cover. It is an ornamental carpet, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.