Professional mermaid performer Mirella Ferraz was reached out on Facebook by series creator Glória Perez to help prepare Isis Valverde in her role as a mermaid. Valverde started having classes for three months before production for this series started. According to Ferraz, when she first told her mother that Glória Perez had contacted her, Ferraz's mother replied "Who? Carla Perez?"
Juliana Paes's character is inspired by Fabiana Escobar, known as the "Pot Queen". Escobar was married to a prominent drug dealer, Saulo Sá (the "Pot King"), who acted at the Rocinha slums in Rio. Glória Perez initially wanted to create a series focused on this character only.
Isis Valverde's second "mermaid"/"siren" role after Siren's Song (2013) in which she starred in the title role.
Fábio Assunção was originally cast as Eugenio but dropped out in favor of a future Rede Globo series. Dan Stulbach was cast instead.