Abstract: Abstract: Head-to-tail directional transportation of freshwater fish is essential to the automatic pre-processing of fish bodies. However, the current orientation of freshwater fish from the head to tail depends mainly on the manual operation with the high labor intensity and low mechanization. In this study, the typical bulk freshwater fish was taken as the research object. A novel reciprocating vibration was utilized to explore the directional transportation of freshwater fish parallel to the head-to-tail axis. The experimental procedure was: 1)The friction characteristics of fish bodies were determined on the conveyor belts with different surface structures, thereby analyzing the orientation feasibility of fish bodies from head to tail in the horizontal direction. 2) A reciprocating vibration system was proposed to realize the head-to-tail directional transportation of fish bodies with constant orientation with respect to the head-to-tail axis. A test device was designed to verify if the trial-produced response followed the predefined characteristics. 3) An orthogonal experiment was conducted to clarify the effect of main factors on directional transportation of freshwater fish from the head to tail. The main factors included the type of conveyor belt, fish scale, vibration frequency, and amplitude. Four types of freshwater fish were used in the test. The duration for the directional transportation of fish body was selected as the indicator. The test results show that the directional transport effect of fish body was the best, when the surface structure of conveyor belt was an inverted triangle structure. The head-to-tail orientation of fish body was achieved when the surface of fish body was scaled or removed. Specifically, the average time was 2.42 s for the directional transportation of fish bodies with scale, whereas, the average time was 3.39 s for those without scale. In Crucian carp with scales, when the vibration frequency was 5 Hz and the amplitude was 120 mm, the head-to-tail directional transportation of fish was achieved, where the duration of directional transportation was 2.65 s. In 4 types of freshwater fish, when the vibration frequency was 5 Hz and the amplitude was 120 mm, the average time was 2.45 s for directional transportation of fish with scale, and the average time was 3.43 s for that without scale. The research finding can provide the theoretical basis and technical reference for the development of freshwater fish bodies in potential orientation equipment.