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The study of fish parental care is important for understanding the social structure and improving the survival rate and welfare of fish populations in aquaculture. However, little is known about the parental care of fish at present, especially their attack patterns, behaviour patterns and spatiotemporal statistical characteristics. In this study, Aequidens rivulatus was taken as the research object and the parental care processes were recorded including the attacker, the attackee, and the start and end attack time. Then, the attack pattern, behaviour pattern and their changes over time were further analysed. The results were as follows: (1) no biting occurred most frequently (58%) and had the highest velocity and acceleration during the parental care period compared with lateral biting and frontal biting. (2) Male attacked intruder the most (52%) with the lowest velocity and acceleration, while female attacked male the least (7%) with the highest acceleration. (3) There was a shift in the role of protection of larvae from females to males. This shift occurred approximately 30 h after the first parental care action. These results suggested that A. rivulatus display a high degree of parental care and an obvious pattern of young protection when facing intruder, which is an important consideration when designing breeding and holding facilities.

The mating roles of males and females, to a certain extent, are dynamic and variable. Several factors influence the mate choice process. Nonetheless, the main preference features have not yet been fully understood in Aequidens rivulatus. In this study, because of its natural pairing characteristics, A. rivulatus was selected to explore the mate choice preferences of different sexes. Specifically, male and female behavioral performances were described and quantified through a “no-choice paradigm” during mate choice. A total of 12 behavioral performances were defined in male mate choice (experiment 1), whereas 14 behavioral performances were defined in female mate choice (experiment 2). According to the obtained results, unselected females did not display any proactive behaviors in experiment 1, whereas unselected males exhibited proactive behaviors in experiment 2, including quivering, nipping, tail beating, swimming up and down, and aggression. It was also found that both male and female individuals tend to express dislike rather than like. Those behaviors with higher frequencies (e.g., quivering) often mean less energy expenditure, thus easier repeatability. Moreover, principal component analysis (PCA) was employed to extract and identify mate choice preference features. Preliminary results indicated that male preferences for a mate were mainly associated with body size, behavioral intention, and appearance, whereas the intensity of female preferences was in the order of body size, appearance, and behavioral intention. In addition, sex hormone levels were associated with mate choices.