The Chinese section of the Irtysh River Basin and the Ulungur River Basin, two major river basins of the Altay region, are located at the northwest of Xinjiang Uygur Autonomous Region of China. As an international river, the Chinese section has seven state-level protected fish and seven local-level protected species as well. Many more commercial species have been introduced from eastern China and other countries, accompanied by some low-value and small-sized fish in recent decades. The non-native fish species have already threatened these protected fish. This study investigated the distribution of non-native fish species in the Chinese section of the Irtysh River Basin and the Ulungur River Basin. The basic data for the biodiversity conservation and the information of the non-native fish in these two river basins were gathered. There are a lot of studies on native fish in the Chinese section of the Irtysh River Basin and Urungur River Basin in China, but there is a lack of studies on non-native fish. Thirteen non-native fish belonging to four orders, nine families and 12 genera were collected in this study. The study includes one dataset. The dataset presents taxonomy, distribution, water body and location for each of the non-native fish collected from the Chinese section of the Irtysh River Basin and the Ulungur River Basin. Our study has found that the proportion of native species has declined, while the number of non-native species has increased from 2013 to 2022. The information we provided could help to develop an international strategy for the protection of aquatic biodiversity.

The Tumen River, which delineates the border between China, North Korea, and Russia, is a vital river in Northeast Asia. Understanding its current fish diversity holds significant scientific value for aquatic ecological protection. Therefore, traditional and eDNA sampling were conducted from 2022 to 2023. Integrating the historical literature with our field collection results reveals that the Tumen River has a total of 64 native fish species, of which 51 species have been surveyed in the wild. The fish composition is mainly dominated by cold-water species, with a high proportion of these being rare, endangered, and nationally protected. eDNA surveys are crucial complements in boundary rivers where traditional methods are not feasible. The results indicated that α diversity values were highest in the Hunchunhe River, attributed to the favorable natural geographical conditions and effective conservation efforts. Recently, the fish diversity in the Tumen River has been disrupted, primarily reflected in the absence of migratory species such as Oncorhynchus gorbuscha and Pseudaspius hakonensis. The study suggests that establishing nature reserves, preventing and controlling alien species, and strengthening international cooperation are key to protect fish diversity.

Biological invasion is a major driver of biodiversity loss and ecosystem disruption, with non-native aquatic species threatening ecological integrity and economic stability. The Qinling Mountains, located in central China, serve as a crucial barrier between temperate and subtropical climate zones, and separate the Yellow and Yangtze River basins. This study investigates the role of these geographical barriers in regulating the distribution and invasion risk of non-native aquatic species. We identified 27 non-native species in Shaanxi Province based on occurrence records compiled from field survey conducted between 2012 and 2024 (and from 2019 to 2024 in the Yellow River mainstream of the Shanxi–Shaanxi Gorge), including 13 high-risk species, such as Trachemys scripta elegans, Procambarus clarkii, Sander lucioperca, and Hypomesus olidus. Using the Aquatic Species Invasiveness Screening Kit and species distribution models, we identified the Hanjiang River in the Yangtze basin and Weihe River estuary in the Yellow River basin as high-risk areas for these species. Mean annual temperature was the primary environmental factor influencing species distribution, with species adapted to cooler conditions predominantly found north of the Qinling Mountains, while those preferring warmer climates are more common in the south. Our findings highlight the Qinling Mountains as both a physical and climatic barrier, limiting cross-basin dispersal and creating distinct invasion patterns. However, human activities such as inter-basin water-transfer projects, damming, and aquaculture practices have gradually weakened the barrier’s effectiveness, facilitating the spread of invasive species. We recommend prioritizing monitoring efforts in cross-basin water-transfer regions, focusing on high-risk species adapted to both cooler and warmer climates, and incorporating environmental DNA (eDNA)-based monitoring in recipient areas of inter-basin water-transfer projects for early detection and control to minimize ecosystem damage.

The Yongding River, the largest river flowing through Beijing, is a major tributary of the Haihe River system. It holds significant ecological, economic and social importance in northern China. However, due to the climate change and anthropogenic activities, parts of the tributaries and lower mainstream of the Yongding River have dried up in recent decades. To alleviate the water scarcity crisis of the Yongding River, ecological water replenishment was initiated in 2020 based on the Middle Route of the South-to-North Water Diversion Project and the Wanjiazhai Yellow River Diversion Project. As a result, the fish population structure and diversity of the Yongding River may change accordingly. In this context, before large-scale water replenishment started, we conducted two field surveys in the summer and autumn of 2019 to assess fish diversity in the Yongding River Basin. This study provides information of 45 fish species belonging to nine orders, 18 families, seven subfamilies and 33 genera in the Yongding River Basin. Our study includes one dataset that presents taxonomy, distribution, water body and location for each species collected from the Yongding River. The provided data can assist other researchers in assessing the impact of water replenishment on aquatic biodiversity and the broader ecological environment of northern China.