Telomere-to-telomere gapless genome assemblies of Coreius heterodon and Coreius guichenoti

Coreius heterodon and Coreius guichenoti are endemic cyprinid fishes of the upper Yangtze River Basin. C. guichenoti is classified as Endangered (EN) by the IUCN and listed as a national second-class protected wild animal in China, whereas C. heterodon is classified as Not Evaluated (NE) by the IUCN. However, genomic resources for these species have remained limited, constraining evolutionary and conservation genetic studies. Here, we present near telomere-to-telomere genome assemblies for both species. The assemblies span 1.09 Gb for Coreius heterodon and 1.08 Gb for Coreius guichenoti , with contig N50 values of 43.10 Mb and 42.62 Mb, respectively, and are anchored to 25 chromosomes. Repetitive elements account for approximately 58% of each genome, and 25,876 and 25,778 protein-coding genes were annotated, respectively. Both assemblies exhibit exceptional completeness, with BUSCO scores exceeding 98.9%, confirming their high quality and reliability. These genome assemblies provide high-resolution resources for future studies on genome evolution, adaptive diversification, and conservation genomics of endemic fishes in the Yangtze River Basin.