Subwassertang
Lomariopsis lineata
Also known asRound pellia · Lomariopsis sp. · süßwassertang
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
The origin and taxonomy of subwassertang are unusual: it's a liverwort (Lomariopsis lineata or a closely related species, identification debated) that grows as flat, irregularly branching, semi-translucent green fronds resembling small pieces of seaweed or lettuce. The name 'subwassertang' is German for 'freshwater seaweed,' coined by German aquarists who first introduced the plant to the hobby. Its exact geographic origin is unclear; it may come from tropical Asia. The growth form is unique among common aquarium plants: no stems, no roots in the traditional sense, just flat, branching thalli that slowly expand. The texture is unlike any other freshwater aquarium plant. The taxonomic identity remains debated; molecular analysis has linked it to the fern genus Lomariopsis, but the aquarium form appears to be a gametophyte (juvenile fern stage) that never develops into the mature sporophyte form. This perpetual gametophyte growth is unusual and may explain why the plant looks nothing like a typical fern. The name 'subwassertang' was coined by the German aquarium hobby community and has been adopted internationally despite not being a formal scientific name.
Care notes
Very easy. Grows in any light (low to high), any temperature (18–28°C), any water chemistry, and without CO2. The plant can be attached to hardscape with mesh or thread, left loose in the tank (it sinks naturally and accumulates on the bottom), or stuffed into crevices in driftwood and rocks. Growth is slow; the flat thalli expand gradually, with new growth branching from the edges. Under moderate light with nutrients, growth accelerates slightly but remains slow. The plant doesn't need trimming in the traditional sense; remove excess portions by hand when the mass becomes too large. Subwassertang provides excellent surface area for biofilm, making it one of the best plants for shrimp tanks alongside Java moss. Baby shrimp hide within the tangled fronds and graze on the biofilm coating. The unique seaweed-like texture adds visual variety in tanks dominated by traditional stem and rosette plants. Propagation by fragmentation: break off a piece and place it somewhere else. Any fragment grows. Available from specialty aquatic plant retailers and hobbyist trades; not commonly stocked at general pet stores.