A semi-submersible fish farm (1,100,101) comprises a partially submerged lower part (2) configured to hold a net cage (4,4a-d) therein and having a plurality of substantially vertical columns (5a- d) supporting an upper part (3) in a position above a waterline； the upper part (3) comprising a plurality of substantially horizontal structural members (6a-d) extending between the vertical columns (5a-d). There is also provided a feeding barge (200,200') for a fish farm, comprising a spar (202) having an elongate vertically oriented hull (203) with a ballasted section (204), a topside module (206), and a feed storage (207a, b)； wherein the topside module (206) comprises a feed conveyance system configured for conveying feed from the feed storage (207a, b) to the fish farm.
