For Aranath Bhagwan, “Nandavart” is given as lanchan mainly because:

1. It is one of the Aṣṭamaṅgal (8 very auspicious Jain symbols)

- Nandavart is a very shubh (auspicious) figure, like a complex swastika with many turns. - Such auspicious symbols are naturally connected with Tirthankars, who are the highest auspicious beings.

1. Connection with his name and mother’s dream

- According to Jain tradition, Aranath Bhagwan’s mother saw an auspicious dream of a bejewelled wheel (ara) before his birth. - From this, he got the name “Ara-nāth”. - Nandavart is also a special “wheel‑like” auspicious diagram, so it fits very well with this dream and his name.

1. Symbol of prosperity and completeness

- Nandavart is taken as a sign of: - great prosperity, - stability, - and completeness. - Aranath Bhagwan was also described as a Chakravarti (universal emperor) in his worldly life, so this symbol matches his grandeur and auspicious influence on the world.

1. Difference of traditions

- Śvetāmbara tradition: lanchan of Aranath Bhagwan is Nandavart. - Digambara tradition: many texts mention fish as his lanchan. - Both are considered very auspicious symbols.

So, Nandavart is given as the lanchan of Aranath Bhagwan because it is an ancient Jain auspicious sign, harmonises with his mother’s dream and his name “Ara”, and reflects his great prosperity and spiritual greatness.

You can read a simple list of Tirthankar symbols here