Methods and procedures are known for the beheading, gutting and subsequent filleting of whitefish as well as sea trout belonging to the Salmonidae family. Basically, a head cut takes place first, in which the head is separated with the collarbone. Guts are removed, and the fish and/or fish parts prepared in this manner are conveyed in a row head-first and belly downwards and processed for filleting with the following steps: the abdominal cavity is opened from below with an abdominal cut, wherein the lower ray bones are cut free from the end of the abdominal cavity to the end of the tail root; the side parts of the fish are separated from the rib bones with a side cut; the rib bones are separated from the backbone by means of a rib bone cut; the backbone is cut free from below up to the dorsal fin roots over the entire length of the fish by means of a backbone cut, wherein the backbone stump produced is still connected with the back meat and the fish fillets are still connected together; a strip including the dorsal fins is cut out on the back side of the fish. Two individual fillets are produced in the last step. The backbone occurs as a backbone stump with the meat clinging to it and, in the conventional process, with a considerable quantity of blood. It is guided to a separation process to recover the remaining meat. The separation process comprises a complex washing process in which impurities, in particular blood, must be flushed out. Blood entering the separated fish meat considerably affects the colour of the fish meat and leads to germ contamination. As a consequence of this, during the separation process, the separated fish meat must be cleaned with the effort described to remove to a large extent the blood influencing the colour of the fish meat and sufficiently reduce germ contamination.