Mitten crab aquaculture is prevalent in China, however, knowledge about the threat of cyanobacteria in mitten crab aquaculture-impacted water bodies is limited. Here, seasonal variations of cyanobacteria and their relationships with environmental factors were investigated for Lake Guchenghu area. Results suggested the changes of cyanobacteria community in crab ponds distinguished from the adjacent lake. In the lake, cyanobacterial biomass (3.86 mg/L, 34.6% of the total phytoplankton) was the highest in autumn with the dominance of Oscillatoria, Aphanocapsa and Pesudanabaena. By contrast, in crab ponds, cyanobacteria (46.80 mg/L, 97.2% of the total phytoplankton biomass) were the most abundant in summer when Pesudanabaena and Raphidiopsis were the dominant species. Of particular note was that obviously higher abundance of filamentous and potentially harmful species (e.g., Raphidiopsis raciborskii and Dolichospermum circinale) were observed in ponds compared to the lake. Specifically, water depth (WD), permanganate index (COD_Mn), total phosphorus (TP), N:P ratio, and ${\mathrm{NO}}_2$ ⁻-N were the key environmental variables affected cyanobacteria composition. For crab ponds, N:P ratio, water temperature (WT) and TP were the potential environmental drivers of cyanobacteria development. This study highlighted the fact that mitten crab culture had non-negligible influences on the cyanobacteria community and additional attention should be paid to the cyanobacteria dynamics in mitten crab culture-impacted water bodies, especially for those potentially harmful species.

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.

Tor sinensis is an emerging aquaculture species in China, yet the effect of dietary protein on its hepatic and intestinal health remains unexplored. This study evaluated the effects of five diets designed to be isoenergetic and isolipidic with graded protein levels (28% to 40%) on juvenile T. sinensis (initial weight: 10 ± 0.4 g) over 60 days. Growth performance improved with increasing protein up to 34%, beyond which it plateaued. Regression analysis indicates that the optimal dietary protein level for both weight gain and specific growth rate is 34.3%. Hepatic antioxidant enzyme activities (SOD and CAT) were highest in the 34% protein group, while triglyceride content was lowest. Histological examination revealed minimal hepatocyte swelling, nuclear displacement, and lipid droplet accumulation at this protein level. Intestinal trypsin activity and villus morphology (height, width, and muscular thickness) were also optimized at 34% protein, though lipase and amylase activities remained unaffected. These findings demonstrate that a 34% dietary protein level supports optimal growth, enhances liver antioxidant capacity, and improves intestinal structure and function in juvenile T. sinensis, providing critical insights for its formulated feed development.

The lower reaches of Yarlung Zangbo River are one of the most important biodiversity hotspots worldwide. Fishes in the area are of great research value, ecological and fishery value, but little biological information about these fishes is available, restricting the conservation and development of local fish resources. This study aimed to provide basic biological data for these fish by studying the length–weight relationships (LWRs) of six indigenous fish species from the lower Yarlung Zangbo River catchment, Tibet, China. Totally, 1262 specimens belonging to four families, six genera, and six species were collected from 2022 to 2024 using various types of fishing techniques. The LWRs of Garra yajiangensis , Nemacheilus subfusca , Creteuchiloglanis kamengensis , and Exostoma tenuicaudatum were reported for the first time to FishBase, except Neolissochilus hexagonolepis and Psilorhynchus homaloptera . The maximum standard‐length information of G. yajiangensis , P. homaloptera , N. subfusca , and E. tenuicaudatum was updated to FishBase. The a and b values calculated from the LWRs ranged between 0.007 and 0.020 and 2.760 and 3.292, respectively. Interspecific and intraspecific variations in LWRs were observed in these fishes. Growth patterns of N. hexagonolepis and C. kamengensis were isometric, while those of other fishes were strongly allometric. Condition factors of species varied between 1.09 and 1.99, and the relative weight ranged from 99.87 to 104.18. Within species, there were significant temporal and spatial variations of LWRs, condition factor, and relative weight for these fishes, respectively. The findings of this study are essential for the conservation and management of local fish and fisheries.

Chinese herbal medicines could be an alternative treatment for antibiotics against fish bacterial disease. The present research was carried out to investigate the antimicrobial potential of 40 herbs against Edwardsiella tarda , Streptococcus iniae and Klebsiella pneumoniae . Firstly, the anti-bacterial activity of forty herbal aqueous extracts (HAEs) was determined using the plate perforation method on brain heart infusion (BHI) agar. Then, effective HAEs were selected to detect the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against the pathogenic bacteria through the micro broth dilution method. Lastly, the inhibitory effects of HAEs combination were also assessed. The results showed that Caesalpinia sappan , Fructus mume , Rhus chinensis and Punica granatum could effectively inhibit all strains of the test bacteria, with the inhibitory circles in 15.00–17.00 mm diameter, MIC and MBC ranging from 31.25 to 62.50 mg/mL and 62.50 to 125.00 mg/mL, respectively. Among the compound of HAEs, the combination of Fructus mume + Rhus chinensis exhibited the most potent antibacterial efficacy against E. tarda and S. iniae , producing inhibitory circles of 19.5±0.41 mm and 19.5±0.41 mm, respectively. The MIC and MBC of this combination against E. tarda were 15.625 and 31.25 mg/mL, whereas, the MIC and MBC of this combination against S. iniae were 7.8125 and 15.625 mg/mL. The compound of C. sappan + F. mume showed the most potent antibacterial efficacy against K. pneumoniae , with inhibition zone diameter, MIC and MBC were 24.50±0.41 mm, 7.8125 mg/mL and 15.625 mg/mL, respectively. Overall, the results indicate that C. sappan , F. mume , R. chinensis and P. granatum showing significant potential for inhibiting pathogens, and their combinations could be a potential alternative to treat the aquatic bacteria diseases.