Reproductive Behavior in Odontobutis potamophila (Günther, 1861)

An animal’s behavior can directly reflect its psychological or physiological condition. The in-depth understanding of fish behavior, especially reproductive behavior, is an important safeguard to promote sustainable aquaculture. In this study, we used the Posture-Act-Environment (PAE) coding system to construct an ethogram of Odontobutis potamophila to help people better judge and identify O. potamophila behaviors; and we designed two groups of experiments to figure out the individual factors affecting the reproduction of O. potamophila. These were the selection of female O. potamophila for male O. potamophila of different sizes, with or without nests, and with or without parental care behaviors, as well as the selection of male O. potamophila for female O. potamophila of different sizes. The results showed that we recorded 14 postures, 22 movements, and 29 behaviors of O. potamophila. Based on their biological functions, the recorded behaviors of O. potamophila were divided into nine types, that is, exploration, territoriality, attack, courtship, mating, parental care, ingestion, stationary behavior, and others. O. potamophila had nocturnal habits, and all the nighttime activities were significantly higher than those during the daytime (p < 0.001). The mating system of O. potamophila was polygamous, and the average mating duration for successful spawning was 9.99 ± 1.23 h. In mate choice experiments, both females and males spent significantly more time stationary than activity (p < 0.001). Females exhibited a slight preference for males with large individuals (strength of preference [SOP] = 53.46%), no nests (SOP = 50.51%), and no parental care behavior (SOP = 55.58%). The results of male mate choice were similar. Although the standard length of females was positively correlated with fecundity (r = 0.61), there were no significant differences in the number of male-to-female choices or duration of association (p > 0.05). This indicated that males showed no preference for larger or high-fertility females (SOP = 47.10%). Therefore, it is likely that males may not be selective for females with different fecundity levels. This study enhances the current understanding of the behavioral patterns of O. potamophila. It establishes a foundation for further research on its reproductive behavior and contributes to the advancement of captive breeding for this species.