The morphological variation in Schizothorax oconnori, Schizothorax waltoni, and their natural hybrids was examined using conventional and image‐based analysis approaches. In total, 38 specimens of S. oconnori, 35 of S. waltoni, and 37 natural hybrids were collected from the Shigatse to the Lhasa section of the Yarlung Zangbo River during June and July 2021. A total of 21 morphometric, 4 meristic, and 27 truss variables were employed for the classification of S. oconnori, S. waltoni, and natural hybrids. Principal component analysis (PCA) and factor analysis (FA), as well as discriminant function analysis (DFA) and cluster analysis (CA), were conducted to identify differences based on traditional and truss measurements. Four principal components explained 75.92% of the variation among the morphometric characters, while five principal components accounted for 79.69% of the variation among the truss distances. FA results showed that factor 1 was associated with head shape, and factor 2 was associated with fins based on morphometric characters. Among the truss characters, factor 1 was related to head shape, and factor 2 was related to chest shape. In DFA, morphometric measurements achieved higher accuracy (100%) compared to truss distances (94.55%). The head morphology of hybrids exhibited intermediate traits between S. oconnori and S. waltoni. Both morphometry‐based and truss‐based clustering indicated that the morphology of natural hybrids leaned toward S. oconnori. In conclusion, the combination of morphometric and truss analysis is beneficial for classifying S. oconnori, S. waltoni, and their natural hybrids. The presence of natural hybrids could be considered an evolutionary response to the differentiation of nutritional and spatial niches in the middle Yarlung Zangbo River.

Per-recruit analyses, with consideration for uncertainty in growth, natural mortality and maturity, were conducted for European bream Abramis brama in the downstream section of the Irtysh River in China to assess its status. The Chapman-Robson method produced an estimate of total mortality rate (Z) of 0.65 year⁻¹. The natural mortality rates (M) were estimated as 0.13 and 0.26 year⁻¹, resulting in corresponding estimates of current fishing mortality rate (F_cur) of 0.52 and 0.39 year⁻¹, respectively. All the estimates of yield per recruit (YPR), spawning stock biomass per recruit (SSB/R) and corresponding biological reference points (BRPs) were sensitive to M. The uncertainty of growth and maturity parameters had limited impacts on the estimates of BRPs, but had a large effect on the YPR and SSB/R outputs. Our findings indicate that A. brama may be at higher risk of growth overfishing than those of recruitment overfishing. In addition, increasing the t_c to nine years might ensure that the spawning potential ratios (SPRs) are above the management targets under all ranges of F with comparatively small impacts on YPR regardless of M. In addition to providing a basic assessment for A. brama in the downstream of the Irtysh River in China, our study presents a comprehensive approach that may be useful for data-limited species in other fisheries.

The Lancang-Mekong River watershed has extremely high fish biodiversity. With the rapid population growth and economic development in the river basin, fish diversity and fishery resources of this river are experiencing serious threats. Basic biological information on most fish species in the Lancang River, required to improve conservation in this area, is limited. This study aimed to provide new estimates of length-weight relationships (LWRs) by using the linear regression of W=aL^b for eight indigenous fish species from the Lancang River, Southwest China. From 2018 to 2021, 534 specimens belonging to 3 families and 8 genera were collected using various types of fishing techniques. Standard length (SL) and body weight (BW) of each specimen were measured to the nearest 0.1cm and 0.1g, respectively. This study presents the first public records of LWR parameters of Schizothorax lissolabiatus, Poropuntius huangchuchieni, Tor sinensis, Scaphiodonichthys acanthopterus, Mystacoleucus lepturus, Hemiculterella macrolepis, Glyptothorax lampris, and Schistura porthos. The range of b values for the LWRs was 2.53783.1732, and the r² values for all LWRs estimates ranged from 0.9102 to 0.9952. Intraspecific difference of b values across population and/or season was observed in S. lissolabiatus, T. sinensis, P. huangchuchieni, S. acanthopterus, and M. lepturus. The range of mean condition factor (K) and mean relative weight (W_r) was 0.972.39 and 100.29108.18, respectively. This study updated information for FishBase and provided new record of maximum standard length for five species, namely, S. lissolabiatus, P. huangchuchieni, T. sinensis, S. acanthopterus, and M. lepturus. The findings of this study are essential for the management and conservation of locally indigenous fish and fisheries.

The lower reaches of the Yarlung Zangbo River are one of the most important biodiversity hotspots worldwide. With the rapid economic development in the area coupled with global climate change, the fish resources and diversity of this region are experiencing serious threats. Basic biological information on most fishes in the river is limited, restricting the conservation of local fish resources. This study aimed to provide estimates of length–weight relationships (LWRs) for six fish species from the lower Yarlung Zangbo River catchment, Tibet, China. From 2023 to 2024, 4034 specimens belonging to two families, five genera, and six species were collected using various types of fishing techniques. The LWRs of five species, namely Schizothorax curvilabiatus, Schizothorax molesworthi, Pseudecheneis sulcata, Parachiloglanis hodgarti, and Exostoma labiatum were reported for the first time to FishBase, except Garra tibetana. The b values calculated from the LWRs ranged between 2.738 and 3.172, and the r² values for all LWRs estimates ranged from 0.931 to 0.989. Sexual variations of LWRs were observed in S. molesworthi and P. sulcata; seasonal variations were detected in S. curvilabiatus, S. molesworthi, G. tibetana, P. sulcata, and P. hodgarti; and geographical differences were discovered in S. molesworthi, G. tibetana, P. sulcate, P. hodgarti, and E. labiatum. Additionally, this study updated information for FishBase by providing a new record of maximum standard length for S. curvilabiatus, S. molesworthi, G. tibetana, and P. hodgarti and a new record of total length for P. sulcata. The findings of this study are essential for the management and conservation of locally indigenous fish and fisheries.

Underwater noise pollution, driven by human activities, is an emerging environmental concern, yet its effects on fish behavior and physiology remain poorly understood. As a vertebrate model with conserved stress pathways, zebrafish (Danio rerio) is well-suited for investigating the mechanistic basis of such impacts. We hypothesized that daytime and nighttime noise exposure would differentially induce anxiety-like behavior and associated neuroendocrine disruptions in zebrafish, with effects varying by sex. To evaluate this hypothesis, adult zebrafish were exposed to anthropogenic noise (100–1000 Hz, 130 dB) for seven days, specifically during daytime (08:00–20:00) and nighttime (20:00–08:00) periods. Behavioral assays revealed that noise exposure delayed the first entry of females into the top zone during daytime, while both sexes exhibited prolonged bottom-dwelling and reduced exploratory behavior under nighttime noise. Physiological analyses showed elevated plasma cortisol levels in females, accompanied by up-regulated HPI-axis genes, whereas males displayed a non-significant cortisol increase. Neurotransmitter profiling indicated a sex-specific response to nighttime noise: In females, brain 5-hydroxytryptamine (5-HT) showed a non-significant increasing trend, whereas in males it was significantly elevated, while dopamine (DA) decreased in both sexes. Gene expression analysis further revealed disruptions in 5-HT and DA pathways. These findings demonstrate that underwater noise induces anxiety-like behavior in zebrafish by dysregulating endocrine and neurotransmitter systems, with nighttime noise exhibiting more pronounced effects, suggesting that chronic exposure to anthropogenic noise may impair natural behavior and stress regulation in aquatic species, particularly during nighttime periods.