The Thirteenth Year

In "The Thirteenth Year," a young boy named Cody Griffin discovers he's turning into a merman, with scales, fins, and the ability to communicate with fish, as he approaches his 13th birthday. As he navigates this transformation, Cody must come to terms with his true identity and decide whether to embrace his new life or return to his old one. Along the way, he learns that his birth mother was a mermaid who left him on a boat to avoid capture, and his adoptive parents advise him to avoid water at all costs. Despite the risks, Cody attends a swim meet and wins, but his scales and arm fins reappear, causing a power surge and revealing his secret to his classmates. With the help of his friend Jess, a marine biology expert, Cody tries to turn back to normal, but the scales are lasting longer, and he must face the reality of who he truly is.

You can stream The Thirteenth Year on: Disney+ Amazon Store

Some movies that have similar genres and were produced around the same time as The Thirteenth Year include Jumanji, Lemony Snicket's A Series of Unfortunate Events, Toy Story, The Wild Thornberrys Movie, Snow Day, Zeus & Roxanne.