The Little Mermaid
Arista appears during the "Daughters of Triton" sequence, singing with her sisters. Afterwards, she only appears in cameos alongside her other sisters. After Ursula dies from being impaled by the bowsprit, she watches with her father and other sisters as Ariel marries Prince Eric.
The Little Mermaid (TV series)
Arista's most important appearance is in the episode "Beached". This episode shows that she and Ariel are prone to fighting, such that Triton "beaches" (or grounds) them both from attending a carnival with the rest of the family. When two gators named Ebb and Flo attempt to steal the royal treasure, Arista and Ariel have to work together; despite their constant arguing, to protect the castle. Arista confesses that she always secretly envied Ariel's adventurous lifestyle.
In the episode "Trident True", when Arista tries to put on her lipstick, she gets upset by having too much of it. She is the only one who appears in the episode "Against the Tide", where she states that Ariel has brought bad luck to Atlantica by rescuing a "Bad Luck Creature".
The Little Mermaid II: Return to the Sea
In the sequel, Arista and Alana are mysteriously absent from the group shots featuring Ariel's sisters. No explanation is made regarding her absence.
The Little Mermaid: Ariel's Beginning
In the prequel film, Arista is introduced as one of the seven daughters of King Triton and Queen Athena. After her mother dies in an accident, She, like her sisters, is raised very strictly by their governess, Marina Del Rey. She is shown to have a difficult relationship with Aquata. They are prone to arguing, and Arista is known for borrowing Aquata's things without asking. She is the first of her sisters to ask Ariel if she can come along to the Catfish Club. She quickly discovers a passion for playing music, and towards the end of the film, she joins the band.