A fluid filter, in particular a thermally sterilizable fluid filter, for purifying substances contained in a fluid, in particular through microfiltration, nanofiltration or ultrafiltration of the fluid, - with a filter housing which features a fluid inlet, a retentate outlet and a permeate outlet; - with a filter cartridge disposed in the filter housing and extending in the axial direction with respect to the longitudinal axis of the filter housing and which features a filter medium; and - with at least one, preferably rubber-elastic, deformable gasket (40, 42, 52), which rests against the filter cartridge in the radial direction in a circumferentially sealing manner and by means of which the filter cartridge is disposed so as to be retained on the filter housing with axial play, - wherein an overpressure area of the fluid filter that can be pressurized with the fluid is sealed with respect to a permeate collection chamber using the gasket (40, 42, 52), said permeate collection chamber engaging around the filter cartridge in the radial direction on the exterior side, preferably in a ring-shaped manner, and/or which passes through the filter cartridge, - and wherein the at least one gasket (40, 42, 52), in particular a gasket (40, 42, 52) allocated to the fluid inlet, features a sealing lip which can be pressed against the filter cartridge by the fluid in proportion to the pressure to an operating pressure of the fluid prevailing in the overpressure range of the fluid filter, characterized in that a retaining ring is disposed radially between the filter housing and the filter cartridge adjacent to the gasket (40, 42, 52), wherein the retaining ring features a plurality of retaining bulges extending from a first radius to a second radius, wherein the retaining ring is designed to rest against the outside surface of the filter cartridge radially inside in a retaining area and to rest against the filter housing radially outside. - with a filter housing which features a fluid inlet, a retentate outlet and a permeate outlet; - with a filter cartridge disposed in the filter housing and extending in the axial direction with respect to the longitudinal axis of the filter housing and which features a filter medium; and - with at least one, preferably rubber-elastic, deformable gasket (40, 42, 52), which rests against the filter cartridge in the radial direction in a circumferentially sealing manner and by means of which the filter cartridge is disposed so as to be retained on the filter housing with axial play, - wherein an overpressure area of the fluid filter that can be pressurized with the fluid is sealed with respect to a permeate collection chamber using the gasket (40, 42, 52), said permeate collection chamber engaging around the filter cartridge in the radial direction on the exterior side, preferably in a ring-shaped manner, and/or which passes through the filter cartridge, - and wherein the at least one gasket (40, 42, 52), in particular a gasket (40, 42, 52) allocated to the fluid inlet, features a sealing lip which can be pressed against the filter cartridge by the fluid in proportion to the pressure to an operating pressure of the fluid prevailing in the overpressure range of the fluid filter, characterized in that