Flounder is Ariel's best friend. He is not very brave and is scared easily, but whenever Ariel is in distress, he rises up to help her out in any type of situations.
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.
Flounder is a round, yellow fish that more closely resembles a convict tang than a flounder. He has sky blue stripes along his top side. His pectoral, dorsal, and tail fins have alternating sky blue and dark sky blue stripes. His dorsal fin lines his back and is frayed near the front, vaguely reminiscent of hair. He seems to have dark eyebrows, a round nose, and a pink, human-like tongue, all dissimilarities to real fish. Flounder's eyes are aquamarine.
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 for three days by sea witch Ursula, he and the others stayed near the princess to assist her. He is also present during most of the Atlantica songs, and in the last performance, sings with Sebastian before Sora and his friends set off.
At the end credits, Flounder is seen watching as Ariel marries Eric, now in true human form.
Flounder first appeared in Disney's 1989 movie The Little Mermaid. He also appeared in its 2000 direct-to-video sequel, The Little Mermaid II: Return to the Sea as an adult fish. In the film he is the only character that supports Ariel's fascination with human things. In the first movie he was voiced by Jason Marinm and in the sequel he was voiced by Cam Clarke.