An experimental ecological method was used to study the effects of water temperature, photoperiod, and light intensity on the survival, feeding, and growth of juvenile Schizothorax irregularis and Diptychus maculates. The Box–Benhnken experiment was designed to predict the optimal environmental conditions for juvenile growth. With the maximum specific growth rate at 15 °C and a photoperiod of LD16:8, the results demonstrated that the juvenile S. irregularis had a survival rate of over 85% in water temperatures ranging from 5 to 25 °C. A daily light duration of 15.86 h and a light intensity of 1166.28 lx, with the water temperature maintained at 10.45 °C, allowed the juvenile S. irregularis fish to attain the optimal circumstances for growth and survival. At water temperatures below 25 °C, the juvenile D. maculates exhibited maximum specific growth rates at 10 °C and LD16:8 light period. Additionally, as the light intensity reached 1000 lx, the juvenile fish grew better. Furthermore, the juvenile D. maculates fish achieved theoretically optimal survival and growth circumstances when the water temperature was maintained at 10.87 °C with a light period of 15.0.5 h per day and a light intensity of 1474.68x. The results showed that both fish species may be raised in captivity in highland regions, but precise control over water temperature is required.

Perca schrenkii populations are experiencing significant declines, yet comprehensive morphological studies are still lacking. Understanding the relationship between morphological traits and body weight is crucial for conservation and breeding programs. We analyzed 13 morphological traits in 100 P. schrenkii specimens from Hamsigou Reservoir using correlation analysis, path analysis, and principal component analysis (PCA). Body weight exhibited the highest variability (CV = 39.76%). Strong correlations were observed between body weight and body length (R = 0.942), total length, and body width. A four-variable regression model explained 94.1% of body weight variation, with body length showing the strongest direct effect (path coefficient = 0.623). The first three principal components accounted for 76.687% of the total variance. Our findings demonstrate that BL, BW, BD, and ES can effectively predict body weight, providing valuable insights for the conservation and selective breeding of P. schrenkii.

To test the performance of COI-based DNA barcoding in species delimitation, we amplified and sequenced the mitochondrial COI gene from six Schizothoracine fishes endemic to Xinjiang, China. We then characterized the COI gene dataset, quantified genetic divergence, and inferred phylogenetic relationships using distance-based approaches. Morphological examination supported clear phenotypic differentiation among taxa. In particular, Diptychus maculatus can be readily distinguished from the densely scaled Schizothorax species by having a single pair of barbels and relatively sparse scales. The COI gene sequences showed an evident AT bias (55.1%), consistent with patterns reported for teleost mitochondrial genomes. Across all samples, 11 haplotypes were identified. Pairwise comparisons indicated a maximum interspecific divergence of 15.296%, whereas the smallest interspecific distance (0.262%) occurred between Schizothorax barbatus and Schizothorax irregularis. Species-delimitation analyses and phylogenetic reconstruction supported D. maculatus and A. laticeps as distinct mitochondrial lineages, whereas S. biddulphi, S. eurystomus, S. irregularis, and S. barbatus were not fully resolved by COI gene. The shared haplotypes and low genetic distances among the four Schizothorax species may reflect recent divergence, incomplete lineage sorting, or historical gene flow. Overall, COI gene barcoding is effective for distinguishing the major lineages in this dataset, especially D. maculatus and A. laticeps.