Sirenix (Form)

Sirenix is the second transformation of Season 5. It is water related and the Winx looked for this ancient power to fight the villain Tritannus as their Believix powers (along with the opaque and unbent wings) were too weak underwater. In addition, they would need Sirenix in order to enter the Infinite Ocean. The Trix also got the Sirenix power from Tritannus, called Dark Sirenix which help them to swim faster with their tentacles instead of a bent and flexible seashell shaped wings.
 * Previous Transformation: Harmonix
 * Next Transformation: Unconfirmed

Overview
According to Miss Faragonda in Return to Alfea, the Sirenix power is an ancient power that was born of the magic of the ocean and it will make the Winx more powerful underwater since their Believix power is less effective under the sea. She also mentioned that no one had acquired Sirenix for a long time and that Daphne was the last fairy who had acquired it and that she was the only one who knew where the ancient Sirenix Book is hidden.

When Bloom asked Daphne about the location of the Book of Sirenix, Daphne told her not to look for it because when the Ancestral Witches attacked Domino, she acquired Sirenix and was ready to fight them by using it, but the Witches had placed an evil spell on Sirenix and when Daphne tried to use Sirenix it turned against herself and caused her to become a spirit without a body. Bloom ended by persuading Daphne, who reveals that the Sirenix Book is in the Magical Archives of Alfea.

The Source of the Sirenix power is found in the cave where Daphne dwells in Lake Roccaluce which grants Sirenix powers to Fairies who have completed the Sirenix Quest. It also protects the Sirenix powers of Sirenix fairies.

Requirements
The fairies need to find the Gem of Self Confidence, Empathy and Courage within one lunar cycle in the oceans that are all over the magic dimension, or they would lose their powers forever. After that, they needed to activate the source of Sirenix in Lake Roccaluce. Then the fairies' Sirenix boxes will appear along with there Sirenix Guardians, who combine ther powers to open the portal to the Infinite ocean. Finally,Omnia, the Supreme Guardian of Sirenix will appear with the portal to the Infinite Ocean which the fairies needed to cross into and they became Sirenix fairies.

It is unknown whether Witches can also be allowed to acquire Sirenix by the Sirenix Quest, as the Trix, the only Witches known to have acquired Sirenix, obtained it after Tritannus stole it from Daphne, a Sirenix Fairy, and gave it to them.

Dark Sirenix
After Tritannus forced Daphne to tell him where the source of Sirenix power was, Tritannus headed to Lake Roccaluce to destroy the Source of Sirenix permanently, so Daphne can't protect her Sirenix from being stolen by him. After he destroyed the source (which was later restored by the Winx using their Harmonix powers and the powers of the Selkies), Tritannus absorbed Daphne's Sirenix powers and used his trident to give a dark version of Sirenix to the Trix.

Magical Abilities
It allows the Winx to fight Tritannus in the Infinite Ocean where their Believix powers are too weak. Also Sirenix grants the Fairies and Trix access to the Infinite Ocean without absorbing all of the Selkies' powers like Tritannus did. Once the Winx have pleased their destiny; they are each given one single wish by their Sirenix Guardians.

Sirenix Wish
On gaining Sirenix, a Fairy is given a wish which she can ask her Guardian of Sirenix to grant it once she has accomplished the purpose for which she acquired Sirenix. The limitations of the wish are however unknown.

Sirenix Curse
Sirenix was cursed by the Ancestral Witches before Daphne acquired it, and it caused the Sirenix power to turn against Daphne herself when she tried using it to defend herself from the Witches. It's unknown if the Curse affects to the Winx, as well as the Trix and Tritannus.

Fairies
The girls' hair is longer than in their Harmonix, and like a long ponytail, somewhat like Icy's hair, except for Tecna, whose hair is shorter than the other girls' are. Also their hair color changes when they go underwater. For example, Bloom's becomes carrot orange with teal streaks, Stella's becomes green with pink streaks, Flora's becomes pinkish-purple with brunette streaks, Aisha's becomes honey blond with purple streaks, Musa's becomes purple with orange streaks, and Tecna's hair becomes violet with blonde streaks.

Their outfits consists of a sparkly mermaid skin top, a belt, a transparent seaweed skirt over mermaid skinned colorful leggings with tail fins and boots with ribbons wrapped around them. The girls also have bracelets made of a piece of jewelry and strips of cloth wound around their arms, and a piece of jewelry in their hair. There is a single pair of seashell shaped wings which shine when the Fairies are swimming.

Witches
The girls become clothed in a body suit that looks like as if made of oil. The suit is less revealing and darker than fairies' Sirenix form with makeup smeared on there eyes and lips, with there hair slightly altered. Instead of seashell-shaped wings, they gain long flowing tentacle which help them to swim faster like an octopus and their version of Sirenix is known as Dark Sirenix.

It must be noted that Dark Sirenix is created by Tritannus, so it can't be considered as real witch form.

Trivia

 * Sirenix comes from the Siren which was the name given to legendary creatures who lived on islands at the entrance of the Strait of Messina found between Sicily and southern Italy and which lured sailors with their enchantingly beautiful and melodically soft hypnotic singing voices and vocalizing tunes to shipwreck on the rocky coast of their island. They were originally portrayed as being half-woman half-bird creatures. Later they began to be portrayed as half-woman half-fish and their English name came to be Mermaids in this appearance. In most languages: "sirena", "sirene" or another variation of these is how mermaids are still called.
 * This is the first transformation in the series that is available for both fairies and witches.
 * The Trix' Sirenix reminds some fans of Ursula and Morgana from "The Little Mermaid" and "The Little Mermaid II: Return to the Sea".
 * The creators redesigned the Sirenix looks in the transformation after it was leaked from Comic Con.
 * When the Winx are in Magix, Sirenix will appear in two-dimensional animation but when the Winx are in the Infinite Ocean, it will appear in three-dimensional animation.
 * This is the most dangerous power among all fairy levels because of a curse.
 * When the Winx use Sirenix on land, they'll retain their original hair color but with added colorful highlights and when underwater, their hair will change a completely different color.
 * The Sirenix song was reworked, yet the original lyrics retained. Also, the Sirenix song is the first transformation song which possess a dance-pop genre.
 * Flora resembles as Princess Krystal and Roxy in her Sirenix form underwater.
 * Sirenix is the first transformation to grant a wish to Fairies that possess it. However, it is still unknown if Dark Sirenix gives the user a free wish.
 * The fact that Sirenix has the ability to grant wishes may be derived from the fact that in Mythology, mermaids have the ability to grant wishes.
 * This is the only transformation which is not a power-up, earned by the Trix.
 * Dark Sirenix allows the user to grow tentacles and even control them and was a name given by the Queen of Sirenix' Guardians, Omnia.
 * Tritannus can enter the Infinite Ocean because he has all of the Selkies' power, while the Trix can enter the Infinite Ocean because they have Dark Sirenix.
 * This is the first transformation to match both animations: 2-Dimensional and 3-Dimensional.
 * During Musa's Sirenix Transformation 2D, her arm ribbon first appears on her left arm, even though it's really supposed to be on her right arm. However, when she strikes her final pose, the ribbon seems to be in the correct position.
 * Flora's Sirenix Wings appeared to be smaller than the actual size in her 2D Sirenix final pose.
 * Stella's hightlights are in pink in 3D transformation, but become purple in 2D one.
 * It's possible that Sirenix may give the Winx a special power, such as Stella's Light of Sirenix. Yet this is the first special power that doesn't feature any graphical effect background.
 * It's unknown if Daphne had already used her Sirenix wish or not.
 * Aisha's ponytail looks pretty loose in 2D version, but much tighter in the 3D one.
 * Flora has pink highlights on her hair, but in 2D transformation and scenes, they mostly disappear.
 * Bloom's hair turns into a darker shade of orange, but in her 3D color change her hair goes back to its original color.
 * It could be possible that the Trix loses their Sirenix power as it is shown on the trailer.
 * Oddly, Aisha appears in all 3 episodes in which the Winx earn 3 mystical gems to finish the Quest of Sirenix.