design: High-molecular-weight genomic DNA was extracted from muscle tissue of a wild-caught Phoxinus grumi individual. The DNA integrity and purity were assessed via agarose gel electrophoresis and spectrophotometry. Sequencing libraries were constructed following the standard Illumina protocol. Briefly, the qualified genomic DNA was randomly sheared to a target insert size of approximately 350 base pairs using a Covaris ultrasonicator. The fragmented DNA then underwent end-repair, A-tailing, and ligation of Illumina-indexed adapters. The resulting libraries were purified and PCR-amplified with a limited cycle number to enrich for properly ligated fragments. Final library quality and size distribution were confirmed using an Agilent Bioanalyzer. Paired-end sequencing was performed on an Illumina NovaSeq X Plus platform.