Vietnam Rotala

Rotala sp. 'Vietnam' was introduced to the aquarium trade by the Japanese company Rayon Vert and has not yet been identified to species, so the trade name stands. Its native range is unrecorded. In the wild it populates shallow waters and wet ground, and the submersed form is said to resemble Rotala hippuris, with requirements close to those of Rotala wallichii. Under moderate light it stays green with reddish stems, while intensive light brings out a golden tint. Provide medium to strong light, an optimum temperature of 22 to 28 °C, a pH range of 4.5 to 7, and carbon dioxide levels of 20 to 40 mg/l; CO₂ injection helps it colour up. Phosphate around 1 to 2 mg/l produces thicker stems and a reddish tone, and an iron shortage shows as small, weakly coloured shoots. It grows vertically with many lateral shoots and is increased by cuttings of the tops.