is a single-season breeder, which dies soon after reproduction. It is important to study the reproduction of . Male size plays an important role in mating competition. This study set out to explore the differences in courtship, competition, and mating behavior between different size male . An experiment with three treatment groups (1L1S, 1L2S, and 1L4S; where L and S represent large- and small-size males, and the number represents the amount of experimental male ) was conducted. A video camera was used to record the reproductive behaviors of during the experimental process. Four different types of behaviors (mate behavior, aggressive behavior, submissive behavior, and accompany behavior) were analyzed over a 2-day period. It was shown that exhibited clear territorial and guarding behaviors during the breeding season. With the increasing proportion of smaller males in the treatment groups, the dominance hierarchy of the large-sized males changed, in which the duration of guarding behaviors and number of successful mating attempts decreased among the large males, while those for the smaller males increased. When there were not enough smaller males in the treatment group, the larger males often actively attacked the smaller ones. When the number of smaller males increased, they actively attacked the larger males to strive for the chances of guarding and mating. The results show that male size has a significant influence on competition and mating behaviors, which potentially corresponds with the determination of male sizes and male-female ratio during breeding. These results may improve the breeding efficiency and contribute to the stock enhancement and development of .