How does the catfish – the largest freshwater fish in Europe, the terror of fish, nutria and even pigeons – gradually colonize all our waterways without ever eradicating other species?

Coming from the rivers of the East, the catfish has colonized almost all the lakes, canals and rivers of Europe since 1950. As an adult, this giant does not encounter any competition, and sits at the top of the aquatic food chain. .

Shads, pike, or ducks, nothing can resist it. It adapts quickly, and even learns to beach itself voluntarily to catch pigeons! It has become the largest freshwater fish in Europe, much larger and heavier than the fishermen who facilitated its irresistible conquest. After more than half a century of terror and impunity, should we declare this invader "harmful"? To answer this, the film presents the contrasting points of view of pro and anti catfish fishermen, relayed by environmentalists. It documents the objective work of biologist Frédéric SANTOUL who seeks to solve an enigma: why, in all the rivers where it has been introduced, has the catfish not eliminated any other fish?

Director: Bertrand LOYER