Spinibarbus sinensis, also known as Qingbo, is an important economic fish in China. However, the detailed mechanisms underlying its growth are still unknown. To excavate the genes and signaling pathways related to its growth, we compared the transcriptome profiles of the hepatopancreas tissues of S. sinensis, with two groups of growth rate for evaluation. An average of 66,304,909 and 68,739,585 clean reads were obtained in the fast growth (FG) and slow growth (SG) group, respectively. The differential gene expression analysis results showed that 272 differentially expressed genes (DEGs) were screened between the FG and SG groups, including 101 up-regulated genes and 171 down-regulated genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis results showed that GO terms related to metabolic process, organic substance metabolic process, and catalytic activity were enriched, pathway signals related to steroid biosynthesis and protein digestion and absorption were also detected. Meanwhile, the potential key regulatory genes sst2, fndc4, and cckra related to the growth of S. sinensis were screened. Reverse transcript fluorescence quantitative PCR (RT-qPCR) validation of 18 DEGs associated with growth differences showed that the RT-qPCR results were consistent with RNA-seq analysis, and nine genes, stk31, gpr149, angptl1, fstl1, sik1, ror2, nlrc3, pdlim2, and nav2 were significantly expressed in the FG group. bmp1, stc1, gpatch8, sstrt2, s100a1, ktf6, cckar6, sync1, bhlha15, a total of nine genes were significantly expressed in the SG group. This study provides basic information for improving the growth characteristics of S. sinensis and the functional research of candidate genes.

The terminal reservoirs of water transfer projects directly supply water for domestic, agricultural, and industrial applications, and the water quality of these reservoirs produce crucial effects on the achievement of project targets. Typically, fish assemblages are monitored as indicators of reservoir water quality, and can also be regulated for its improvement. In the present study, we compared traditional fish landing (TFL) and environmental DNA (eDNA) metabarcoding methods for monitoring fish assemblages in three terminal reservoirs of the East Route of the South-to-North Water Transfer Project, China. Results of TFL and eDNA showed similar assemblage structures and patterns of diversity and spatial distribution with obvious differences in fish composition across three examined reservoirs. Demersal and small fish were dominant in all reservoirs. In addition, a strong association between water transfer distance and assemblages and distribution of non-native fish was found. Our findings highlight the necessity of the fish assemblage monitoring and managing for water quality and revealed the impact of water diversion distance on the structure of fish assemblages and dispersal of alien species along the water transfer project.

Procypris rabaudi, commonly known as the rock carp, is an endemic economic fish in the middle-upper reaches of the Yangtze River. To enhance the understanding the biology of rack carps, a high-quality reference genome is required in different areas of study. Here, we generated the first telomere-to-telomere genome assembly and annotation of the rock carp, which spans 1.64 Gb with a contig N50 of 32.36 Mb. Hi-C assembly suggested that 99.83% sequences were positioned to 50 pseudo-chromosomes. Notably, 43 chromosomes were assembled without any gap. Through the integration of homologous-based predictions and RNA-sequencing technology, we identified 44,402 protein-coding genes, with 43,663 of them (98.3%) predicted to be functional. Furthermore, our assembled genome achieved 98.1% BUSCO completeness. This work improves the quality of the rock carp genome and provides valuable foundation for the future studies of genomics, biology and the fishery resources breeding.

This study used environmental DNA (eDNA) metabarcoding to monitor fish communities at 14 sites along the upper Yangtze River across four seasons, aiming to understand seasonal variations in community structure. This study reflects on the current status of fish community structure in the region by leveraging an analytical discussion on the composition of fish species and functional groups, the application of 16 multidimensional diversity indices, and the relationships between fish communities and environmental variables. A total of 120 fish species were detected. The communities predominantly consisted of species that produce sticky eggs, are sedentary, and have omnivorous diets. However, the sequence reads of species producing drifting eggs, migratory, and carnivore fish groups were higher in autumn and winter compared to spring and summer. Except for the functional evenness index (FEve), all other functional diversity indices, as well as α diversity, taxonomic diversity, and phylogenetic diversity indices, were higher in spring and summer compared to autumn and winter. This suggests that fish diversity is greater in spring and summer due to increased fish activity during the spawning season and higher eDNA shedding and detectability under warmer conditions; however, ecological niche overlap is more pronounced during these seasons. This study provides practical experience for fish monitoring based on eDNA metabarcoding technology.

Procypris rabaudi, a member of the Cyprinidae family and genus Procypris, has been designated as a national second-class protected wildlife species in China due to a significant decline in its wild populations. Understanding its genomic characteristics and mitochondrial genome structure is crucial for germplasm conservation and systematic classification. In this study, we utilized high-throughput sequencing to investigate the genome of P. rabaudi. The genome size was 1.5 Gb, with a heterozygosity rate of 0.44% and 61.47% of repetitive sequences. We identified 1,151,980 simple sequence repeats (SSRs), with mononucleotide repeats being the most abundant at 55.34%. The complete mitochondrial genome was assembled with 16,595 bp length. A phylogenetic tree constructed from 13 mitochondrial protein-coding genes indicated that genus Procypris was most closely related to genus Luciocyprinus and formed a monophyletic group with Cyprinus, Carassioides, and Carassius. Pairwise Sequentially Markovian Coalescent (PSMC) analysis revealed a rapid population expansion prior to the Last Interglacial Period, followed by a decline after reaching its peak during Last Glacial Period. Notably, P. rabaudi exhibited a two-peak demographic pattern during both the Last Glacial Period. These genomic data provide valuable resources for the conservation of P. rabaudi germplasm and for future studies on cyprinid classification and evolution.