A high-quality chromosome-level genome assembly and annotation of the Amur grayling (Thymallus grubii).

Graylings (Thymallus) represent one of the earliest diverged salmonid subfamilies and provide crucial insights into the evolutionary consequences of the salmonid-specific whole genome duplication event (Ss4R). Here, we present the first chromosome-level genome assembly of the Amur grayling (Thymallus grubii), an economically and ecologically important species endemic to East Asian freshwater systems. The final assembly spans 1,754.51 Mb with 46 pseudo-chromosomes, achieving a contig N50 of 3.03 Mb and anchoring 99.97% of sequences to chromosomes. The genome contains 31,867 protein-coding genes with 97.58% functionally annotated. Repetitive sequences comprise 52.64% of the genome, dominated by DNA transposons (22.06%). BUSCO analysis indicates 97.9% completeness for conserved Actinopterygii genes. This high-quality genome assembly provides an essential resource for salmonid comparative genomics, aquaculture breeding programs, and conservation genetics of this economically important species.