Glaucus was a mortal fisherman who was transformed into a sea-god after eating a magical herb. He was the patron god of fishermen.
Glaucus fell in love with the beautiful nymph Scylla and wanted her for his wife, but she was appalled by his fish-like features and fled onto land when he tried to approach her. He asked the witch Circe for a potion to make Scylla fall in love with him, but Circe fell in love with him instead. She tried to win his heart with her most passionate and loving words, telling him to scorn Scylla and stay with her. But he replied that trees would grow on the ocean floor and seaweed would grow on the highest mountain before he would stop loving Scylla. In her anger, Circe poisoned the pool where Scylla bathed, transforming her into a terrible monster with twelve feet and six heads.