All individuals used in this part of study were sacrificed within 1 month after the behavioral tests, and the prosoma were kept at -80 for further analysis. We used three extremely aggressive individuals with a mean score higher than 3.5 points from HA group and three extremely non-aggressive individuals with a mean score lower than 0.5 point for transcriptome analyses. We did not use individuals from the middle group because they seem less aligned with personality traits in their predatory behavior. During extraction, we first transferred each sample into a 1.5ml Eppendorf with 0.5ml trizol, and ground them thoroughly with a polypropylene grinding rod. Then RNA extraction was performed according to the protocols on the website of Thermo (https://reurl.cc/gQo4eb), and Nanodrop was used to access the quality (value of A260/280) and concentration of the RNA. Before library construction, we performed DNase treatment using the Invitrogen TURBO DNA-free Kit from Thermo (https://reurl.cc/MXo4Wp). Then, we constructed libraries using Universal Plus mRNA-Seq with NuQuant (https://reurl.cc/WqoRVL, TECAN). After library construction, Qubit 2.0 Fluorometer with dsDNA High Sensitivity Kit and DNA 1000 assay of Agilent 2100 Bioanalyzer were used to access the quality and concentration of each library. When RNA quality was satisfactory 2 x 151bp paired-end sequencing was performed using NovaSeq 6000 sequencing system. After sequencing, QC test and trimming were conducted using QV20 by CLC Genomics Workbench v10 to prevent low-quality sequences from affecting further analyses.