Rotala indica 'Bonsai' is best described as a compact, moderate growing version of Bacopa caroliniana.  Plant it in small groups and trim it often. Cuttings may be re-planted in the group to achieve a more dense group or carpet.  At high light the tip of the stems may become reddish, at lower light the leaves will become larger and the plant less compact.  Rotala 'Bonsai' is particularly suitable for nano-aquariums. 

Source : tropica.com