He was voiced by Jason Marin in the 1989 film, both Edan Gross and Bradley Pierce in the television series, Parker Goris in the prequel and Kingdom Hearts II, and Cam Clarke, as an adult in the sequel.
Flounder scares easily, and is prone to panicking under stressful situations, but when Ariel is in trouble, he comes through for her without hesitation.
In the film, he is the only character to give unconditional support for Ariel's fascination with human things, and at one point gives Ariel a statue of Eric as a gift. He is first seen after the preformance, Daughters of Triton with Ariel after sneaking away. When Ariel confesses she is in love with Eric, she strikes a deal with an evil sea witch. Flounder joins Ariel in Eric's Kingdom as she tries to win his heart.
Because he can't survive above water, he is forced to only be able to get news from Scuttle or Sebastion nearby water. He was persistent in asking if they were kissing, showing how dearly he wanted Ariel to get her happy ending.
Flounder joins Sebastian, Scuttle and other fish in the song Kiss the Girl. Later, Flounder helps Ariel defeat Ursula who is planning to capture Ariel by battling Flotsam and Jetsam. When Ursula is killed, Flounder attends the wedding and gets a good-bye kiss as she and Eric enjoy their marriage. He is voiced by Jason Marin in the 1989 film and the album called Sebastian From The Little Mermaid.
Flounder appears in all the episodes of the prequel television series, sharing constant adventures with Ariel. In the series, he is voiced by Edan Gross and Bradley Pierce. He generally tries to serve as a voice of reason in comparison to Ariel's more adventurous nature, but usually goes along with her anyway. He is often seen giving rides to Sebastian, who cannot swim as fast as Flounder or Ariel. According to the television series, Flounder's real name is Guppy Number 35. In the episode "Land Of The Dinosaurs", when he has been found frozen in an ice cube, Ariel thaws him with King Triton's trident and he gets a cold resulting in his sneezing.
The episode "The Evil Manta" shows that Flounder and Ariel met as young children, though Flounder initially mistook Ariel for a large fish that intended to eat him. The same episode shows Flounder outsmarting Evil Manta, who had been trying to spread prejudice throughout Atlantica. Flounder simply fakes believing Manta's words then works with Ariel to fix the problems Manta caused. The episode "The Beast Within" has Flounder being bitten by a dangerous Howling Hairfish; he then begins to transform into one himself. However, Ariel is able to cure him with the assistance of silverfish.
Flounder has a small role in The Little Mermaid II: Return to the Sea, where he is voiced by Cam Clarke. He is reunited with a grown-up Ariel and takes part in the search for Melody. He is shown as an adult and became a father himself, having a number of five children of his own.The Little Mermaid: Ariel's Beginning, in which he first meets Ariel (contradicting the TV series) and later unknowingly leads her to the Catfish Club, where he works as a waiter, but dreams of being a part of the the Catfish Club Band. His characterization is notably different in this movie; he doesn't scare as easily and is much more carefree and high-spirited. It is possible that he became more worrisome after the first few adventures with Ariel. He's obsessed with music, constantly humming and beatboxing even at inappropriate moments, which, given that music is forbidden in Atlantica, lands him into trouble on more than one occasion, but which also helps others keep their spirits up, most notably when his beatboxing kicks off the reprise of "Jump In The Line (Shake, Senora)" when he, Ariel, Sebastian and the Catfish Club Band are on the run from Atlantica. In this film, he is voiced by Parker Goris.
When Sora, Donald, and Goofy first arrive, Flounder was chased by Heartless with Ariel and Sebastian, but was saved by the trio. Because Sora and the others were new to the sea world, they did not know how to swim flexibly. Flounder, then became their instructor and was chased so he could teach them.
When Ariel and the others set off to find the Keyhole, Flounder was the one who told them about the dolphin that would help them swim against the water currents.
Flounder appears as a fragment of Sora's memories. In this story, he was sent to the surface by Ursula so she could use him to make Ariel steal the Trident from her father. Towards the battle, Ariel was supposed to choose between giving the Trident to Ursula or losing Flounder. Ariel willingly gave up the Trident so that Flounder would not lose his life - but Sora defeated Ursula in the end.
When Sora, Donald and Goofy revisited them, Ariel was under deep depression. Flounder wanted to cheer her up, and so he showed them a statue that resembled Prince Eric and asked them to move it to Ariel's cave. When Ariel was turned into a human by sea witch Ursula, he and the others stayed near the princess to assist her.
Flounder can be seen in the first sequence of the show with Sebastian during Under the Sea.
Flounder is seen in computer animation with Ariel and later during the Under the Sea sequence.
Flounder can be seen with Ariel during her Part of Your World segment of the show.
Flounder is makes a cameo when Donald enters the Little Mermaid segment. He has only one line: "Cool!".
Flounder appears in the stage adaptation of The Little Mermaid. His supporting role is similar as in the film, but he does not give Ariel the statue of Eric, and does not help Ariel reach Eric's wedding barge, as the Vanessa subplot has been removed. However, Flounder performs a new song titled "She's in Love", which he sings with Ariel's sisters when they notice that Ariel has been acting "fishy lately". The stage role was originated by Cody Hanford and J.J. Singleton, but the two actors had to leave the show when their height overshot that of Sierra Boggess, who originated Ariel. The role was taken over by Trevor Braun and Brian D'Addario. On the Original Broadway Cast Recording, Brian D'Addario performs as Flounder. He is voiced in Japanese by Rica Matsumoto as a child and Yūji Mitsuya as an adult.