A sea-pen arrangement (1) for farming fish, the sea-pen arrangement ( 1) comprising : - a service unit (2) with a plurality of shafts (23) projecting downwards and provided with a pontoon (25) at their lower portions, the shafts (23) defining an inner area (20) and - a net (33) forming a closed enclosure (35), and the sea-pen arrangement (1) further includes: - at least one sea pen (3) positioned in an outer area (29) on the outside of two shafts (23) and - a frame structure (4) comprising an upper frame (41) with a first fastening portion (410) and a second fastening portion (419), a bottom frame (43) and a fence (45) fastened to the upper frame (41) and the bottom frame (43), the frame structure (4) is fastened to the service unit (2) at the fastening portions (410, 419), and the frame structure (4) surrounds the at least one sea pen (3) in the outer area (29).
