Abstract: We used juvenile black rockfish (Sebastes schlegelii) to investigate the impact of the 5-HT1A receptor gene on aggression control in this study. The administration of 5-HT1A receptor agonist, 8-OH-DPAT, was utilized to evaluate its impact on aggression among juvenile black rockfish. Subsequently, different aggression phenotypes within the juvenile groups were scrutinized for genetic variations in the 5-HT1A receptor gene, aiming to identify potential SNP markers correlated with aggression. Our findings showed that fish treated with 8-OH-DPAT exhibited significantly reduction in the frequency and duration of aggressive behavior compared to the control group (P<0.05). The latency period for aggression was significantly higher in the treated group (P<0.05). We discovered seven significant polymorphic sites linked to attack phenotypes in the 5-HT1Aα promoter region (P<0.05): SNP 1236, SNP 1245, SNP 1260, SNP 1301, SNP 1302, SNP 1309, and SNP 1330. Additionally, two polymorphic sites were significantly associated with attack phenotypes in the 5-HT1Aβ promoter region (P<0.05): SNP 892 and SNP 1147. However, no significant polymorphic sites were identified in the coding region of the 5-HT1A gene in relation to attack phenotypes (P>0.05). In summary, the results demonstrate that activating the 5-HT1A receptor effectively inhibits aggressive behavior in black rockfish. Furthermore, we also identified SNP loci within the 5-HT1A receptor gene that are associated with different aggression profiles.