A fluid filter has a plurality of inlet channels, a plurality of outlet channels, and filter walls separating the inlet channels from the outlet channels. The inlet channels are parallel to the outlet channels, and the filter walls have a plurality of pores through which the inlet channels are connected to the outlet channels. A cross-sectional area of all inlet channels is larger than a cross-sectional area of all outlet channels, and a value of diameters of the pores of the filter walls calculated by mercury porosimetry being a median value d50, being between 0.01 μm and 0.5 μm.