Dwarf sagittaria
Sagittaria subulata
Also known asDwarf sag · Awl-leaf arrowhead · Narrow-leaved arrowhead
Water parameters
Light and nutrients
Substrate type: any. Propagation: runners.
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
Native to the Americas, along the coastal eastern United States from Massachusetts to Louisiana and again in Colombia and northwestern Venezuela, in shallow pond margins, slow streams, marshes and estuaries. Sagittaria subulata, the awl-leaf arrowhead, belongs to the family Alismataceae and grows as grass-like rosettes of narrow flat leaves that spread fast by runners into dense mats. The 'dwarf' name is only half true: in bright light the leaves stay short, around 5–8 cm, but in low light or rich water they stretch to 20 cm or more, behaving more like a midground plant. True to its tidal origins, it tolerates low-salinity brackish water and even forms meadows in estuaries, an unusual trait among aquarium plants that suits it to mildly brackish aquaponics. It has been recorded as a minor non-native in Britain (now largely gone), the Azores and Java.
Care notes
One of the very best carpeting plants for low-tech tanks, and realistically the only one that will spread aggressively without CO2 below about 50 PAR. It grows across low to high light, in soft or hard water around pH 6 to 8 and a wide temperature band, and tolerates a little salinity. Under strong light with CO2 it stays short, 5–8 cm, and runs hard, carpeting in four to six weeks; under low light without CO2 it grows taller and slower but still fills in over six to ten weeks. Plant small portions a few centimetres apart, and a nutrient-rich substrate or root tabs speeds colonisation, though it manages even in plain sand. Once knitted in, the runner mat crowds out algae. Trim the tops to hold height and push lateral spread, which matters more in low light where it grows tall enough to hide background plants. Propagation is automatic by runners. It is a good first carpet for anyone not ready for CO2. As a hardy, brackish-tolerant grower it is genuinely usable in aquaponics.