|First seen||The Power Of Harmonix|
When the fairies manage to open the Book of Sirenix, the search begins and the book gives along the Sirenix boxes, the power of Harmonix, in order that they can move quickly underwater, overcome obstacles and solve the riddles from the book and so pass to Sirenix.
The outfit of a Harmonix fairy has three colors related to each other and consists of a top with a strap over one shoulder, a belt, a skirt or tutu with a transparent train that gives the appearance of a mermaid tail. High-heeled sandals with long ribbons of two different colors that reach legs. The hair is long and can be decorated with a tiara or marine oysters and the wings are slightly smaller than those of Believix so the fairies can overcome any obstacles during the search.