Genome sequencing, comparative analysis, and gene expression responses of cytochrome P450 genes in provide insights into environmental adaptation.

The mangrove fish () serves as a model for researching environmental adaptation and sexual development. To further such research, we sequenced and assembled a high-quality 842 Mb reference genome for . Comparative genomic analysis revealed 891 expanded gene families, including significantly expanded cytochrome P450 () detoxification genes known to be involved in xenobiotic defense. We identified 69 () across 18 families and 10 clans using multiple methods. Extensive RNA-seq and qPCR analysis demonstrated diverse spatiotemporal expression patterns of by developmental stage, tissue type, sex, and pollutant exposure (17β-estradiol (E2) and testosterone (MT)). Many exhibited sexual dimorphism in gonads, suggesting reproductive roles in steroidogenesis, while their responsiveness to model toxicants indicates their importance in environmental adaptation through enhanced detoxification. Pathway analysis highlighted expanded genes in arachidonic acid metabolism, drug metabolism, and steroid hormone biosynthesis. This chromosome-level genomic resource provides crucial biological insights to elucidate the functional roles of expanded in environmental adaptation, sexual development, early life history, and conservation in the anthropogenically impacted mangrove habitats of . It also enables future ecotoxicology research leveraging as a pollution sentinel species.