In a fish processing machine consisting of fish body feeder, decapitator, belly filleting and viscera removing device, and dark-colored flesh removing device, the fish body feeder is designed to transport the fish body supplied in lying position by feeding onto the tray while aligning the back-belly direction uniformly, and the dark-colored flesh removing device is intended to separate the ordinary flesh and dark-colored flesh of the fish body efficiently to remove the dark-colored flesh.