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 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 pair of bent and flexible seashell-shaped wings