Device for supply of feed to a floating sea pen (600) exhibits a cyclone (200) arranged on a raft (100) provided with a framework (101) and floats (102a, 102b). A conduit (206) provides air-transported feed tangentially to the upper part of the cyclone (200). Numerous air vanes (205) are connected to a shaft (304) and further with water vanes (303). The air vanes (205) are driven by transport air from the feed supply and operates the water vanes (303) to pump water from the sea pen via inlets (301a, 301b, 301c, 301d) and into the internal of the cyclone (200) via water outlets (302a, 302b) to mix feed and water. The cyclone (200) is arranged at least partially submerged under the water surface (w) and exhibits feed outlet conduits (401, 402) extending down into the sea to release feed beneath the lice belt. The device is optionally submerged by a sea pen cover (103) to protect fish from injury when jumping. An underwater camera (500) is optionally arranged liftable between a submerged operational position to a retracted position inside a protecting housing (503) located above the water surface (W) to prevent fouling of the camera lens.