Rotala

Rotala is a large genus of aquatic plants in the family Lythraceae, distributed widely across tropical and subtropical wetlands of Asia, Africa, and the Americas. In the aquarium hobby numerous species are cultivated — most notably R. rotundifolia and R. indica — as essential background stem plants prized for their capacity to color red to orange under intense illumination and CO2 enrichment. Leaves are small and grow opposite along slender stems. The more light and iron-rich liquid fertilizer provided, the deeper and more vivid the red coloration becomes. Dense, bushy backgrounds are achieved through regular trimming and replanting of cut stems. Many species are forgiving for beginners, though requirements vary considerably between species, making species selection important.

CO2 recommended + liquid fert (iron is key for red color)