Sirenix is the second and most powerful transformation from Season 5.
To obtain the Sirenix, a fairy must find gems of empathy, self-confidence and courage during a lunar cycle, otherwise she will lose her powers forever. Later, go to the Lake Roccalucce to activate the source of Sirenix along with the Guardians of Sirenix, who combined powers open the portal to the Infinite Ocean. There Omnia, the supreme guardian of Sirenix, appears stating that the quest is over and the Sirenix was gained.
A Sirenix fairy has long hair with some stripes of different color, also is tied up in a pony tail. Her outfit consists in a bright top, a transparent skirt with pants with mermaid designs below and boots decorated with some ribbons. Also the fairy has a bracelet, some ribbons around one the arms and some pieces of jewelry on the hair. She also have wings shaped oysters, which are not very big so the fairy can move fast.