<p>The international community has reached a consensus to facilitate knowledge of living resources in the Central Arctic Ocean (CAO), where the demersal fishes remain largely unexplored. The Chukchi Borderland is currently one of the few viable areas for bottom trawling within the CAO because it possesses some gentle terrain and has experienced severe seasonal sea ice retreat. In this region, we report an unexpectedly speciose demersal fish fauna with unique zoogeographic patterns based on the most extensive fish surveys conducted by the Chinese National Arctic Research Expedition (CHINARE). Several fish species were recorded here for the first time, which is crucial for updating their geographic ranges and assessing their distribution shifts. Cods (Gadidae), eelpouts (Zoarcidae), and sculpins (Cottidae) were the dominant families, which may have diverse origins and intensified competition that revealed by otolith chemistry and stable isotope analyses. The key species, polar cod (<i>Boreogadus saida</i>), exhibits high mobility and flexible feeding strategies that contribute to its high biomass. Fish assemblages in the Chukchi Borderland have been significantly influenced by sea ice and oceanic inflows, thereby the individual northwards movement and rising biota and nutrients in this region are assumed to increase its fish species richness and biomass. Our findings highlight the importance of scientific monitoring and research in comprehending the impacts of climate change on fish, which is essential for future conservation and sustainable fisheries management in the CAO.</p> Graphical abstract <p></p>