Rotala wallichii
Rotala wallichii
Also known asWhorled rotala · Wallich's rotala
Water parameters
Light and nutrients
Substrate type: nutrient rich. Propagation: stem cuttings.
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 |
With fish
Origin and habitat
A delicate, fine-leaved stem plant of the loosestrife family, Lythraceae, Rotala wallichii (Hook.f.) Koehne, named for the Danish botanist Nathaniel Wallich who worked in 19th-century India and Southeast Asia. It is native from India (West Bengal) and Bangladesh through Myanmar, Thailand, Laos, southern China and Taiwan to peninsular Malaysia, in soft, slightly acidic wetland water. The very fine, needle-like leaves sit in dense whorls along thin stems, giving a soft feathery look like Myriophyllum, but under high light with CO2 the whorls flush vivid pink to magenta-red, making it one of the most striking stem plants in the hobby. It is regarded as one of the more demanding Rotala, for experienced high-tech keepers, though tissue culture has made it easier to obtain than in the days of wild-collected stock.
Care notes
Demanding. It needs strong light, roughly 50 PAR and up, pressurised CO2 around 20 to 30 ppm, and careful, steady nutrient dosing; under poor conditions the fine lower leaves shed and the plant rots from the bottom up. Crucially it wants soft, slightly acidic water, about pH 5.5 to 7 and 2 to 8 GH, and deteriorates in hard or alkaline water. Iron is key to the pink-red colour, and nitrate should be kept low but never zero, around 10 to 15 mg/L at most. The needle leaves trap detritus and catch algae in an unbalanced tank, so consistency matters more than heavy dosing. Plant in dense groups of ten or more for effect, trim the tops and replant, though it branches less reliably than R. rotundifolia. Keep it around 22–28°C. It is not a beginner plant, but in a dialed-in high-tech tank the glowing magenta whorls are among the most beautiful things in aquascaping. It is an ornamental, not a crop, so it is unsuited to media-bed aquaponics or hydroponics.