Fitting (1) for a closed cage, wherein the fitting (1) is provided with an elongate first recess (2) for receiving and holding an elongate bead (3) of an upper portion of the cage. The fitting (1) comprises two mutually interlocking members (4, 5), which when interconnected together define the first recess (2). The invention also relates to a cage system (10) comprising such fittings (1).