In fish species, there is limited analysis of signature transcriptome profiles at the single‐cell level in gonadal cells. Here, the molecular signatures of distinct ovarian cell categories in adult Nile tilapia ( Oreochromis niloticus ) were analysed using single‐nucleus RNA sequencing (snRNA‐seq). We identified four cell types (oogonia, oocytes, granulosa cell, and thecal cell) based on their specifically expressed genes and...