A filter insert for a filter for filtering a fluid having] an inflow surface, and outflow surface, and a main throughflow direction. A filter body of the insert has a filter medium with pleats forming a pleated bellows, are arranged perpendicular to the main throughflow direction. A first number of the pleat edges form the outflow surface and a second number of the pleat edges on a pre-filtration side of the filtration body form the outflow surface. A first seal prevents the fluid from overflowing from the pre-filtration side to the post-filtration on a surface formed by a first number of of end face of the pleats. A second seal prevents the fluid from overflowing from the pre-filtration side to the post-filtration side on a surface formed by a second number of end faces of the pleats.