A fish cage having one or more air-tight buoyancy rings (1) being entirely or partially hollow, with water valves (20) for inlet and outlet of water, and air valves (3) for injection and outlet of air, and preferably with closing shot plates (2) in the buoyancy ring (1). The novel feature according to the invention is that at least one or more of the air valves (3), and preferably also the water valves (20) are arranged inside of the buoyancy ring (1) so that the air valves (3) and water valves (20) are protected from external mechanical influence.