He is a short light-olive green fish with dark olive green lips. He wears a light purple suit that fits his position, short black hair, and a light purple hat with a yellow feather. He also has a yellow diamond and a "N" in the center of his suit.
He liked that Mindy thinks that Neptune is cruel and inhumane, and wished for him to be compassionate and understandable. Neptune later turned around at the end of the film.