Abstract: This study aims to realize the head, tail and ventral dorsal orientation of fish bodies in conveyors using machine vision technology. The Scomber japonicus was taken as the object of study. The morphological and physical characteristics of the fish were used to design the mackerel body lifting device, the fish body separation device, the fish body head, fishtail and ventral dorsal directional conveying device, the fish body return conveying device, and the directional control system to form the mackerel body directional arrangement conveying device. The fish body lifting device included a spacer conveyor belt and brush rollers to separate and convey the fish upwards; the fish body separation device included a fish sliding mechanism and brush rollers to guide the fish from the lifting device to the fish separating device, in order to separate and convey the fish; the fish body head, tail and ventral dorsal directional conveying device consisted of an image acquisition device, head- and tail- and ventral-dorsal directional actuator to convey the fish in a set head, tail and ventral dorsal directional direction. The fish return conveyor was used to return the fish with the wrong head and tail orientation, in order to the fish lifting device for reorientation. The mackerel dataset was created. The image data was then enhanced with brightness enhancement, Gaussian noise and rotation to enrich the number of training datasets. The annotation of the image data was finally realized. YOLOv5s was selected as the fish head, tail and ventral and dorsal orientation detection model, with an accuracy of 99.76%, a recall of 99.59%, and an average detection accuracy value of 99.5%. The head, tail and ventral and dorsal orientation of the fish were detected in real time on the device. The orientation control system consisted of an Arduino UNO controller, a computer and detection program, a CMOS industrial camera, a head and tail orientation actuator cylinder, a ventral and dorsal orientation actuator cylinder, a solenoid valve, an optocoupler isolated relay, a photoelectric sensor and a power supply. The orientation control system controlled the head, tail and ventral dorsal orientation of the mackerel using the identification results of the fish head, tail and ventral dorsal orientation model, and finally realized that the fish were transported forward in a certain head, tail and ventral dorsal orientation. As such, a prototype of the fish body directional arrangement conveying device was tested to verify the conveying effect of the fish body lifting device at different conveying speeds using the single fish body lifting success rate as the evaluation index. At the same time, the directional success rates of the fish body head and tail, as well as ventral and dorsal were used as evaluation indexes, and the conveying speed of the fish body lifting device, the conveying speed of the fish body separation conveying device, the fish body head, tail and ventral and dorsal directional conveying. A series of tests were performed on the effect of the directional transport of fish in a directional arrangement transport device. The test results show that the fish lifting device effectively separated and lifted the fish at different conveying speeds, and there was no overlapping of the fish upwards. The directional conveying speed of the fish body reached 15 pieces/min when the conveying speed of the fish lifting device was 0.05 m/s, the conveying speed of the fish separating device was 0.45 m/s, and the conveying speed of the fish head, tail and ventral dorsal orientation device was 0.60 m/s. The finding can offer a strong reference for the development of freshwater fish orientation conveyors.