Nanjenshen grows better in high light. Not well in low and medium light. It is specifically identifiable by its thin leaves and slightly orange crowns in high light and CO2.
Rotala indica has shorter and slightly sider leaves - tends to be reddish in high light. It is argued that Rotala Rotundifolia is the same as Indica but I noticed that Rotundifolia tends to be very bushy and pink at the tips where it is closest to the light.
Not the best picture but this is what Rotala Nanjenshen grew out to look like under high light and CO2 when I kept this plant a couple years ago:
Not a hard plant to find. You'll get some!
Free bump!