The little fish who shares the title possesses a huge imagination despite his small stature. He’s perpetually tardy for class, and his explanations to "Miss Skate" grow increasingly inventive. These involve pirate loot, a shark encounter, a massive squid—and even some fishing nets! However, his classmates simply see him as an aquatic version of Pinocchio. Surprisingly, one of these fabricated stories turns out to be real, leading to him being separated from familiar surroundings and lost, requiring a very literal trail of breadcrumbs to guide him back to school and his friend "Johnny Dory." The animation style brought to mind “The Gruffalo,” and I’m fairly certain I spotted a scaled version of that creature somewhere within the film. It's a story with similarities to the boy who cried wolf, told in an appealing way and employing different techniques to differentiate between reality and imagination. There is definitely a lesson to be learned, but it’s presented in a delightful fashion, proving you don't need large studio funding to create a fun underwater adventure that also educates viewers about various types of fish.

Source on TMDB