Fish back opener, its main function is to break the fish from the back or belly, make the fish into butterfly piece or two pieces, which can realize high efficiency and high yield. The fish back opening machine consists of frame, conveyor belt device, cabin, blade, motor, electric appliance, discharge port and so on. The whole machine is made of stainless steel, wear-resistant and durable, safe and hygienic, and can be used for all kinds of fish back opening and filleting, and can be customized with suitable equipment according to the size and characteristics of the fish.