This study focused on T. strauchii in Sayram Lake, Xinjiang. In August 2023, a total of 768 samples were collected to investigate its morphological, age, and growth characteristics. T. strauchii has an elongated body with a slightly raised area behind the head. Its head is flat, the body is slender, the back contour is arc-shaped, the trunk is thick and round, and the tail is short. Principal component analysis (PCA) showed that the cumulative contribution rate of the first three principal components was 53.80%, which reflects the morphological characteristics of the species. Moreover, gender characteristics are not prominently manifested in external morphology. Discriminant analysis showed an accuracy rate of 51.80%, indicating that the accuracy of gender discrimination relying solely on external morphology is limited. The species’ age distribution ranges between 1 and 7 years old, with the dominant age around 3 years old, and age structure showing a unimodal distribution. The relationship between body length and body weight is W = 7.432 × 10⁻⁶L^3.037(R² = 0.995, n = 768). The exponent 3.037 indicates a growth pattern with priority given to body mass growth because it is greater than 3. The von Bertalanffy growth equation was selected to describe the growth of T. strauchii. The body length growth equation is L_t =139.346 [1 − e^{−0.267(t+1.639)}], and the body mass growth equation is W_t = 27.79 [1 − e^{−0.267(t+1.639)}]^3.073. The inflection point age (t_i) is 2.563, the growth coefficient (k) is 0.267, and the growth characteristic index(φ) is 3.715. The growth rate decreases with age, and the growth inflection point ages of males and females differ. The research findings provide basic data for population assessment, resource protection, and rational fishing in fishery resource management. This highlights the ecological adaptability of T. strauchii and emphasizes the importance of comprehensively considering multiple factors in fishery management.

Fish are vital for material cycling and energy flow in aquatic ecosystems. The genus Triplophysa, with over 100 known species, is significant in the Central Asian highlands’ freshwater ecosystems. T. strauchii and T. tenuis, as representatives, occupy distinct ecological niches and face challenges from climate change and human activities. There is a lack of research on Triplophysa fishes’ digestive systems, especially comparative studies, so this research aims to fill this gap. In September 2024, 40 samples of T. strauchii were collected from Sayram Lake and 40 samples of T. tenuis were collected from the Muzat River in Xinjiang. After acclimation, morphological observations (measuring fish and digestive tract parameters) and histological analyses (paraffin sectioning, HE staining, and microscopy) were carried out. The data were sorted in Excel and analyzed with an independent samples t-test in SPSS 27.0. Morphologically, T. strauchii has an obtuse snout, terminal mouth, specific upper lip papillae, and an S-shaped intestine about (1.45 ± 0.11) times its body length, while T. tenuis has an arc-shaped subterminal mouth, fringed papillae, and a spiral-shaped intestine around (0.82 ± 0.09) times its body length. Both possess a digestive tract, glands, and a hepatopancreas attached to the mesentery. Histologically, a large number of club cells were found in the oropharyngeal cavities of both species; their secretions have an adhesive effect on food, aiding food selection. Their digestive systems vary in structure and cell composition: the oropharyngeal cavity has three layers; the esophagus has four layers with more goblet cells in T. strauchii; the stomach has three regions without goblet cells and a thicker muscular layer in T. strauchii; the intestinal wall has four layers with different villi and goblet cell distributions; the hepatopancreas has lobules; and T. strauchii has a typical portal area. In conclusion, this study systematically compared the gastrointestinal systems of T. strauchii and T. tenuis for the first time, revealing significant structural differences related to their niches and feeding patterns as adaptations to specific environments. It fills the research gap, provides a basis for exploring fish ecological adaptation and environmental impacts on digestion, offers new ideas for Triplophysa protection strategies, and guides fish evolutionary biology research and Triplophysa resource protection and utilization.

Aeromonas veronii is a widely distributed opportunistic aquatic pathogen associated with diseases in freshwater fish. Despite the ecological and conservation significance of Diptychus maculatus, a protected cold-water fish inhabiting high-altitude ecosystems, information regarding its associated bacterial communities remains limited. This study aimed to isolate and characterize A. veronii recovered from D. maculatus and provide baseline information on its occurrence and phenotypic characteristics. Eight bacterial isolates were recovered from various tissues, including skin, gills, eye, intestine, dorsal fin, body kidney, gonad, and spleen of randomly sampled fish individuals from Xinjiang, China. Phenotypic and biochemical characterization, together with 16S rRNA sequencing, supported their identification as A. veronii, while gyrB analysis of a representative isolate provided additional species-level confirmation. Antimicrobial susceptibility testing revealed a consistent multidrug-resistance phenotype among all isolates. The isolates were susceptible to enrofloxacin, cefotaxime, ceftriaxone, and florfenicol. Intermediate responses were observed for ciprofloxacin, ofloxacin, doxycycline, oxytetracycline, and trimethoprim–sulfamethoxazole, whereas resistance was detected against norfloxacin, neomycin, penicillin, amoxicillin, tetracycline, and erythromycin. In vitro biofilm assays demonstrated weak to moderate biofilm-forming capacity among isolates. These findings provide baseline data for wildlife microbial surveillance and conservation-oriented monitoring of protected fish populations, supporting future investigations into environmental monitoring, genomic characterization, and host–microbe interactions.