The invention provides a fish processing device for cleaning blood and blood vessels from the spine of a fish, e.g. a salmon, after the visceral has been removed. A jet nozzle for spraying pressurized liquid and a movable suction device with a vacuum nozzle for entering the abdominal cavity of the fish serve in combination to clean the spine of the fish for blood and blood vessels. A controller controls an actuator for moving the vacuum nozzle to enter the abdominal cavity of the fish, and it is then moved in a first direction relative to the transport direction, until the first vacuum nozzle reaches an end of the abdominal cavity of said fish while sucking blood and blood vessels from the abdominal cavity along the spine of said fish. This is repeated by moving the vacuum nozzle in the opposite direction until reaching an opposite end of the abdominal cavity of said fish, where the vacuum nozzle exits the abdominal cavity. Preferably, the fish is continuously transported along with this cleaning process. Some embodiments comprise a second set of jet nozzle and suction device mounted downstream of the fish transport direction to allow even further cleaning of blood and blood vessels along the spine of the fish.