Hygrophila polysperma 'Rosanervig' is normally an undemanding plant.
It may suddenly develop shoots that are entirely green. Remove these to keep the distinctive pink, marbled leaves. If you want deep-pink leaves, you must provide intensive light. Stems become 20-40 cm tall and 5-8 cm wide. The distinctive colouring of the pale leaf ribs is probably caused by a virus which prevents chlorophyll from being produced in the cells around the leaf ribs, making them white. However, this virus does not affect other plants in the aquarium.