A new spined loach, Cobitis beijingensis, is described from Beijing, China. The new species can be distinguished from other congeners by a combination of characters: 1) Lamina circularis on pectoral fin of male elongated, posterior margin slightly serrated; 2) possessing 14–18 (mode 15) pre-pelvic myotomes; 3) pelvic fin inserted below 3^rd–5^th branched dorsal-fin ray; 4) total vertebrae 4+ 36–38 (mode 37); 5) L₂ of the Gambetta’s pattern does not exist or is fused with L₁. The molecular phylogenetic analyses based on mitochondrial Cyt b also support C. beijingensis to be a new species.

Microphysogobio bicolor (Nichols, 1930), a species which has long been synonymized with Microphysogobio fukiensis (Nichols, 1926), is revalidated in this study, based on morphological comparison and molecular phylogenetic analysis. The species can be distinguished from congeners by the following characters: mouth horseshoe-shaped, central portion of anterior papillae arranged in one row, tightly contact with each other, equal or slightly larger than all other papillae on upper lip; lateral-line scales 36–38; branched anal-fin rays 5; posterior chamber of air-bladder length equal to eye diameter; vertebrae 4+32; body usually sharply bicolored. The significant Cyt b gene sequence divergence between M. bicolor and its congeners also strongly support that it is a valid species which represents an individual clade sister to the M. luhensis–M. kachekensis–M. yunnanensis clade. A redescription of M. bicolor and a diagnostic key to all valid Microphysogobio in the Yangtze River Basin are also provided in this study.

Although Microphysogobio tungtingensis (Nichols, 1926) has been treated valid since it was described, its morphology remains vague, especially when comparing it with another similar species, M. elongatus (Yao & Yang, 1977). In this study, the types of both species were examined and also compared with several lots of specimens from a wide geographical range: there is no significant difference in morphology between them. Additionally, molecular evidence supported by mitochondrial gene sequence also showed low genetic distance in between. Thus, it is suggested that M. elongatus is a junior synonym of M. tungtingensis. While revising these two species, a new species, Microphysogobio punctatus sp. nov., was discovered that has a similar distribution with them both. However, it can be distinguished from its congeners by having a globular or oval shaped posterior air-bladder chamber which length 58.6%–82.8% of eye diameter; a narrow upper jaw cutting edge which less than half mouth width; a slender caudal peduncle with depth 34.6%–48.5% of length; and a six-branched-ray anal fin. This new species also has numerous small black spots on all fins which is also unique. The new species is morphologically and molecularly close to M. bicolor (Nichols, 1930).

The Yellow River drainage is a biodiversity hotspot for the Gobio group, but no one has yet reviewed these species systematically. This study examined the type specimens of the species in the Gobio group and numerous newly captured specimens in the Yellow River drainage for an overall morphological comparison. A phylogenetic tree of those species based on mitochondrial cytochrome-b sequences was also constructed. Our results indicate the presence of four species, i.e., Gobio guentheri (this was described as Acanthogobio guentheri), G. rivuloides, G. coriparoides, and G. huanghensis. Morphological and molecular phylogenetic analyses indicated that G. tchangi is a junior synonym of G. huanghensis, while G. meridionalis is a junior synonym of G. rivuloides. Additionally, the phylogenetic analysis showed that the genus Acanthogobio is nested within Gobio. In order to maintain the monophyly of Gobio, this study suggests that the genus Acanthogobio should be a junior synonym of Gobio, and the type species A. guentheri should be treated as Gobio guentheri. Furthermore, the type specimens of Romanogobio johntreadwelli and R. amplexilabris were checked, and this study confirmed that these two species are junior synonyms of G. rivuloides. Therefore, the genus Romanogobio is not distributed in the Yellow River drainage. The Gobio species are primarily distributed in the upper and middle reaches of the Yellow River drainage, from Qushian Township, Qinghai Province, to Sanmenxia City, Henan Province, at an average elevation above 300 meters. A diagnostic key for four valid Gobio species in the Yellow River drainage is provided.

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.