Rise of the Teenage Mutant Ninja Turtles (2018)

S2E1 Flushed But Never Forgotten

The Turtles find themselves facing a familiar foe when Splinter's beloved goldfish, Piebald, who was mistakenly sent down the toilet, returns with a vengeance after consuming an Oozesquito. This unexpected transformation brings a wave of chaos, forcing the Turtles to confront their past mistake while navigating the challenges of their new reality. As they scramble to contain the situation, they must also find a way to remedy their old error before it spirals out of control.