(EN) An apparatus 21 for carrying out a method of processing roundfish, has eight consecutive processing stations. Initially, the fish after catch and ventral cleaning, is individually frozen with a straight shape. At a first station 22, the frozen fish is positioned using a fish positioning device which has upper and lower slot guides, by aligning the fins and straight shape of the fish, parallel to a saw. The frozen fish is then held in place by a retaining device 33 that has a number of fixing means which abut the frozen fish. Each fixing means is partly made up of a fluid absorbing and flexible material. At a second station 24, the saw cuts the frozen fish in a vertical plane to produce two halves. The two halves are turned with the cut facing up, at a third station 25. A fourth station 26 has a detector 27 for locating impurities in the fish meat and records their position. The unwanted impurities are then removed at a fifth station 28 by a tool which is controlled by a control unit which from detector 27 has received information about the position of the recorded impurities. A sixth station 31 releases the cleaned fish halves from retaining device 33. At a seventh station 32, retaining device 33 is then cleaned and the flexible material of the fixing means is moistened with liquid. Finally, at an eighth station the frozen fish is portion packed and freeze-stored.