Subwassertang
Lomariopsis cf. lineata
Also known asSüsswassertang · Round pellia · Lomariopsis prothallium
Water parameters
Light and nutrients
Substrate type: epiphyte. Propagation: fragmentation.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Wood and rock mounts (Hardscape mount) | varies | none |
| Inert sand (Pool filter sand) | neutral / inert | none |
| Inert gravel (Aquarium gravel) | neutral / inert | none |
| Bare bottom (no substrate) (Bare bottom) | n/a | none |
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
With fish
Origin and habitat
Subwassertang, properly Susswassertang (German for 'freshwater seaweed'), is one of the odder aquarium plants. It was long taken for a liverwort because of its flat, ribbon-like, semi-translucent green thalli that branch into something like small pieces of seaweed or lettuce, but DNA sequencing showed it is actually the gametophyte (prothallium) of a fern in the genus Lomariopsis, family Lomariopsidaceae, order Polypodiales, closest to Lomariopsis lineata. Remarkably, it persists indefinitely in this juvenile gametophyte stage underwater and never develops into the mature fern, which is why it looks nothing like a typical fern, with no stems or true leaves, just expanding flat thalli. Despite the German name it appears to come from tropical Africa and Asia, and all the plants in the trade are thought to be clones of a single specimen introduced around 2001.
Care notes
Very easy. It grows in any light from low to high, across a wide temperature range, in almost any water chemistry and without CO2. Attach it to wood or rock with mesh or thread, wedge it into crevices, or just leave it loose, where it sinks and gathers on the bottom; its rhizoids will grip hardscape on their own, and the thalli are far less brittle than the similar Monosolenium. Growth is slow to moderate, the flat thalli spreading from their edges, and it needs no real trimming, just pull away excess by hand when the clump gets too big. It is one of the best plants for shrimp, alongside Java moss: the tangled fronds give huge biofilm grazing surface and hiding space for shrimplets. Its seaweed-like texture adds variety among stem and rosette plants. Propagate by breaking off any piece, which grows on its own. It is an ornamental, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.