A film bag for storing a fluid, in particular a reagent or an auxiliary agent for a biochemical analysis method, includes a film, a seam, and an irreversibly destructible predetermined breaking point. The film is impermeable to the fluid and constituents of the fluid. The seam is formed in a fluid-tight manner between a first sub-region of the film and a second sub-region of the film and forms the film into a fluid-tight bag for accommodating the fluid. The bag is configured to be arranged in a chamber of a device that provides a fluid for a biochemical evaluating unit. The predetermined breaking point is formed from the film and is fluid-tight when a fluid pressure in the film bag is below a limit. The predetermined breaking point is destroyed when the fluid pressure is above the limit.