Abstract

Simple SummaryTheCephalopholis sonneratiis a valuable marine fish species widely farmed for food; however, the fundamental biological mechanisms governing its growth rate remain poorly understood. To address this knowledge gap, we examined 8-month-old tomato hind from the same cohort that exhibited markedly different body sizes (large vs. small individuals). Fish from each size group were randomly and equally assigned to two subgroups subjected to either a one-week starvation treatment or normal feeding conditions. Subsequently, brain and muscle tissues were collected for transcriptomic analysis. Through transcriptome sequencing and network analysis, we found that fish growth is regulated by an integrated system involving both tissues: the brain detects and initiates growth signals, while the muscle carries out growth processes such as protein synthesis and sugar metabolism. Our research uncovers the key biological network behind growth differences in tomato hind, and the findings provide essential information and key genetic targets to help farmers breed faster-growing tomato hind, supporting the sustainability and productivity of this important marine aquaculture industry.The tomato hind(Cephalopholis sonnerati)is a marine aquaculture fish species with high economic value. Elucidating the mechanisms underlying its growth regulation is crucial for the development of the aquaculture industry. To analyze the biological mechanisms underlying growth differences, individuals with extreme body sizes at 8 months of age from the same batch were selected in this study. A combined experiment of “body size × feeding status” was constructed, and transcriptome sequencing and weighted gene co-expression network analysis (WGCNA) were performed on brain and muscle tissues. The results showed that 2553 differentially expressed genes (DEGs) were identified between individuals with distinct body sizes, which were significantly enriched in growth regulation pathways such as PI3K–Akt,