Aquaculture International最新文献

Odontobutis potamophila, a small fish of high economic value in the middle-lower Yangtze River, is currently farmed under two principal systems: recirculating aquaculture and rice-crayfish-Odontobutis potamophila integrated culture. Previous research has emphasized water-saving or yield-increasing aspects, yet systematic comparisons of how these systems modulate the species’ intestinal microbiota remain scarce, constraining optimization and dissemination of healthy production strategies. In this study, two culture modes of Recirculating aquaculture system and rice-crayfish-Odontobutis potamophila integrated culture were set up in the same season and the same region. The composition, diversity, and potential function of gut microbiota were analyzed. At the same time, the blood physiological and biochemical indexes were measured to systematically evaluate the effects of the two culture modes on the intestinal microbial function of O. potamophila. The results showed that there was no significant difference in the dominant phylum of gut microbiota between the two culture modes, but there was a significant difference in the composition of dominant genus. LEfSe analysis found that the composition of the core gut microbiota was significantly different between the two culture modes. A total of five significantly different pathways were identified by the differential analysis of KEGG pathway level 3, all of which were significantly up-regulated under the rice-crayfish-Odontobutis potamophila integrated culture. The up-regulation of these metabolic pathways can enhance the function of energy metabolism and lipid metabolism of the gut microbiota of O. potamophila. The five blood physiological and biochemical indexes (ALT, AST, TG, T-CHO, and GLU) of O. potamophila in recirculating aquaculture system were significantly higher than those in rice-crayfish-Odontobutis potamophila integrated culture. The specific microbiota was significantly correlated with blood glucose, blood lipid, and liver enzyme levels, indicating that gut microbiota may be an important microecological factor causing the difference in blood physiological and biochemical indexes. This study confirmed that different culture modes can reshape the intestinal microbial community of fish, and then regulate the metabolic pressure and physiological health of the body, providing a scientific basis for selecting appropriate management strategies for different culture modes.

We examined the effects of photoperiod and light intensity on survival and growth of kuruma shrimp (Marsupenaeus japonicus) across developmental stages from the zoea–mysis (ZM) to the postlarval (PL) stage, as well as the effect of light intensity on phototactic behaviour. During the ZM stage, growth tended to be higher (p = 0.052) under photoperiods including a dark phase (12L:12D and 18L:6D) than under continuous light (24L:0D) and tended to be higher (p = 0.059) under low to medium light intensities (200 and 1000 lx) than under the highest intensity (5000 lx). In contrast, during the PL stage, growth was not strongly affected by photoperiod but was significantly greater (p < 0.001) at 5000 lx than at 200 or 1000 lx. Although the optimal photoperiod and light intensity differed markedly among developmental stages, survival was not significantly affected by the light environment. In behavioural experiments using a projector to generate different light intensities, larvae at the ZM stage showed strong positive phototactic behaviour (p < 0.05), whereas this behaviour was weaker at the PL stage. These results suggest that kuruma shrimp growth during the ZM stage is enhanced under photoperiods including a dark phase and low-to-medium light intensities. Overall, our findings suggest that the optimal photoperiod and light intensity for M. japonicus shift during development: light regimes including a dark phase and low to medium intensities may favour early larval growth, whereas high light intensity enhances growth at later stages.

Captive reproduction of wild freshwater fish species remains a significant challenge in aquaculture, particularly for ecologically and economically valuable cyprinids. Broadly distributed across the Middle East, the longspine scraper (Capoeta trutta) is now facing population declines due to overfishing, habitat degradation, and river regulation. This study investigated the effects of salmon gonadotropin-releasing hormone analogue (sGnRHa), administered via single injection or sustained-release implantation, on the reproductive performance of wild-bred male C. trutta maintained under captive conditions. A total of 48 2‑year‑old males were collected from rivers in western Iran during the natural breeding season and acclimatized to captive conditions over a 12‑month period. At the time of experimentation, the fish had an average length of ~ 23.8 cm and a weight of ~ 111.6 g. Fish were randomly assigned to three treatment groups: (1) control (0.25 ml/kg physiological saline injection), (2) single sGnRHa injection (Ovaprim, 0.25 ml/kg), and (3) sGnRHa (5 µg/kg) + domperidone (5 mg/kg) implantation using cholesterol–cellulose pellets. Semen and blood samples were collected at 24 and 48 h, and 7 days after single injection or implantation. Results showed that both hormonal treatments significantly increased sperm volume and motility duration compared to the control (P < 0.05). Notably, sperm density and spermatocrit were significantly reduced in the hormonal treatments (P < 0.05). Hormonal treatments also led to a significant increase in serum testosterone (T) and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) levels (P < 0.05), while 11-ketotestosterone only increased significantly in the implantation group. Histological examination of testicular tissue confirmed the presence of spermatozoa in all groups, indicating the potential for spermiation under captive conditions. However, sperm quantity and quality were suboptimal for commercial use without hormonal induction. These findings demonstrate that sGnRHa therapy, whether by single injection or implantation, enhances the reproductive capacity of C. trutta males and can be a valuable tool for developing controlled breeding programs for this declining species.

Bacterial pathogens such as Aeromonas hydrophila and Edwardsiella tarda cause major economic losses in Nile tilapia (Oreochromis niloticus) aquaculture. In this study, we developed and evaluated a bivalent injectable vaccine (IPV) to enhance protective immunity against both pathogens using fucoidan as adjuvant. Fish were vaccinated intraperitoneally and boosted at 28 days post-vaccination (dpv), followed by immune, biochemical, and challenge studies. The IPV group exhibited the highest survival rates, reaching 83% against E. tarda and 77% against A. hydrophila, significantly higher than other treatments and the non-vaccinated control. Vaccinated fish showed enhanced adaptive responses, with upregulation of immune-related genes (IgM, TCRβ, MHC I, MHC II, IFNγ, IL-8) in spleen and head kidney, indicating both humoral and cellular activation with tissue- and time-dependent dynamics. Serum IgM titres were significantly elevated post-vaccination and further boosted at 35 dpv, correlating with improved survival. Non-specific immune markers, including lysozyme, catalase, superoxide dismutase, and bactericidal activity, were consistently higher in the IPV group, reflecting strengthened innate defense mechanisms. Histopathological analysis of spleen and head kidney demonstrated reduced necrosis and preserved tissue architecture in vaccinated fish, confirming vaccine-mediated protection. Collectively, the bivalent IPV vaccine elicited a broad spectrum of immune responses, integrating antigen-specific and innate defenses, and conferred significant protection against two major bacterial pathogens of tilapia. These findings support the potential of bivalent injectable vaccines as a practical prophylactic strategy to reduce disease outbreaks and antibiotic reliance in commercial tilapia farming.

Deep analysis of aquaculture water parameters can improve both the accuracy and efficiency of dissolved oxygen (DO) prediction and help identify key environmental factors essential for precision aquaculture management. To enhance short-term forecasting performance, this study proposes an adaptive graph convolutional–improved long short-term memory (AGCN-ILSTM) model optimized using an improved Superb Fairy-wren Optimization Algorithm (ISFOA). The ISFOA employs a hierarchical learning mechanism to strengthen global exploration and convergence stability. The AGCN-ILSTM model integrates adaptive graph convolutional networks with an improved recurrent learning structure, enabling it to capture complex spatial–temporal dependencies between DO and environmental parameters. The proposed model provides 3-h-ahead predictions and is validated using measured seawater DO data collected from an aquaculture zone in Huguang Town, Mazhang District, Zhanjiang City, Guangdong Province, China. Results show that the model achieves NSE, LMI, and WI values of 0.958, 0.978, and 0.989, respectively, with RMSE and MAE as low as 0.084 mg/L and 0.069 mg/L—significantly outperforming conventional models such as SMI-TCN-BiLSTM, WD-MIC-PSO-SVR, and NGO-CNN-GRU. These findings demonstrate that the ISFOA-AGCN-ILSTM model can accurately perform short-term seawater DO prediction and provide effective support for intelligent and sustainable aquaculture management.

Vibrio harveyi is a major pathogen causing fatal vibriosis in marine aquaculture, resulting in substantial economic losses. This study innovatively explored the infection-mitigating effectiveness and mechanisms of Xiaochengqi Decoction (XCQD), a traditional Chinese herbal formula, against V. harveyi infection using a multi-method approach (in vivo experiments, molecular docking, functional assays, network pharmacology). In kuruma shrimp (Penaeus japonicus), XCQD significantly alleviated V. harveyi-induced intestinal damage, reduced intestinal Vibrio load from 1.6 × 10⁸ to 1.23 × 10⁵ CFU/mL, and preserved intestinal mucosal integrity. Molecular docking revealed that 12 bioactive compounds within XCQD bound to V. harveyi hemolysin (VHH), with four (nomilin, aloe-emodin, narirutin, hesperidin) inhibiting VHH-mediated hemolysis. Furthermore, 12 compounds also suppressed biofilm formation (e.g., hesperetin achieved 89.7% inhibition at 64 μg/mL). Network pharmacology identified 378 potential targets of 47 XCQD compounds enriched in cAMP, TNF, and nitrogen metabolism pathways, with EGFR, HRAS, HSP90AA1, JAK2, MAPK1, and PTK2 as core targets, indicating multitarget modulation of host–pathogen interactions. Our findings highlight XCQD as a promising natural therapeutic for sustainable aquaculture disease control, offering a practical alternative to antibiotics by targeting bacterial virulence and host immunity.

The potential replacement of fishmeal using fermented abalone viscera meal in Oreochromis mossambicus feeds was explored. Five diets were prepared by adding fermented abalone viscera meal at 0% (control), 10%, 20%, 30%, and 40% to replace fishmeal. Diet 6 constituted the fermented abalone viscera meal only. The diets were then denoted as FAV1, FAV2, FAV3, FAV4, FAV5, and FAV6, respectively. Diets (each) were assigned at random to triplicate tanks of O. mossambicus fingerlings (7 ± 1.4 g) and fed for 6 weeks. Specific growth rate was higher in the FAV4 (1.51 ± 0.09), FAV5 (1.74 ± 0.05), and FAV6 (1.68 ± 0.02) diets than in the FAV1 (1.05 ± 0.09), FAV2 (1.12 ± 0.10), and FAV3 (1.21 ± 0.07) diets. Feed intake and weight gain were also higher in the FAV4, FAV5, and FAV6 diets compared to the FAV1, FAV2, and FAV3 diets. Feed conversion ratio was significantly lower (P < 0.05) in the FAV4 (2.73 ± 0.31), FAV5 (2.63 ± 0.28), and FAV6 (2.65 ± 0.19) diets than in the FAV1 (3.34 ± 0.67), FAV2 (3.29 ± 0.54), and FAV3 (3.18 ± 0.38) diets. However, among the viscera inclusion levels (FAV2-FAV5) and the FAV6 diet, the highest growth performance was noted in the FAV5 group. The highest apparent digestibility coefficient values were noted in FAV4 (91.27 ± 3.39%), FAV5 (92.52 ± 3.44%), and FAV6 (92.24 ± 3.82%) while lower values were recorded in FAV1 (86.42 ± 3.11%), FAV2 (86.04% ± 3.18), and FAV3 (87.21 ± 2.96%). The addition of the fermented viscera to the O. mossambicus diets did not affect villi height and width nor goblet cells count. In addition, liver histology was not impacted by the use of the fermented abalone viscera meal across treatments (no enlargement of hepatocytes, sinusoids, or vacuolation). The results indicated that activities of protease, amylase, and lipase were higher in the FAV4, FAV5, and FAV6 diets as opposed to the FAV1 and FAV2 and FAV3 diets. The improved growth performance and enzyme activities in the FAV4, FAV5, and FAV6 diets show that the abalone viscera can be utilised as a protein source in O. mossambicus.

Grouper species are some of the most valuable aquaculture fish worldwide. However, their vulnerability to different pathogens causes considerable economic losses. The galectin-9 gene was identified in the transcriptome of the seven-band grouper Hyporthodus septemfasciatus. The galectin-9 gene was cloned, and its recombinant protein was overexpressed, enabling a detailed analysis of its molecular characteristics. The complete cDNA sequence consists of 2,005 base pairs (bp), encompassing a 162 bp 5′-untranslated region (UTR), an 829 bp 3′-UTR, and a 1,014 bp open reading frame (ORF) that encodes 338 amino acids (aa). SGGal-9 possesses two conserved carbohydrate recognition domains (CRDs): an N-terminal CRD comprising 135 aa and a C-terminal CRD comprising 123 aa. Each CRD in SGGal-9 features two conserved β-galactoside binding motifs (H_NPR and WG_EER). The predicted protein structure lacked signal peptides or transmembrane domains. After sub-cloning the SGGal-9 gene into the pCold I vector, recombinant SGGal-9 (rSGGal-9) was successfully over-expressed as a soluble protein in Escherichia coli (E. coli) BL21 (DE3), induced with 0.1 mM isopropyl-β-D-1-thiogalactopyranoside (IPTG). To assess rSGGal-9 activity, hemagglutination assays were employed using erythrocytes from olive flounder (Paralichthys olivaceus) and sevenband grouper and demonstrated effective aggregation at minimum concentrations of 3.125 μg/mL and 12.5 μg/mL, respectively. Furthermore, the aggregation capability of rSGGal-9 was confirmed in different bacteria, including E. coli, Lactococcus garvieae, Photobacterium damselae, Streptococcus iniae, Streptococcus parauberis, and Vibrio parahaemolyticus. These findings, based solely on in vitro assays, suggest that galectin-9 has bacterial-aggregating properties; however, further in vivo studies are required to evaluate its preventive potential in aquaculture.

In order to evaluate the directly waterborne inoculation of marine red yeast (Rhodotorula mucilaginosa) on the aquaculture of Penaeus vannamei with zero-water exchange biofloc technology (BFT), this study assessed the effects of dosing R. mucilaginosa at four levels (T0, 0; T1, 2 × 10³ cells/mL; T2, 2 × 10⁴ cells/mL; T3, 2 × 10⁵ cells/mL). Yeast was supplemented every 4 days. A total of 91 shrimp (initial body weight, 6.01 ± 1.31 g; body length, 9.79 ± 0.85 cm) were stocked per 350-L tank and reared for 35 days. The experiment consisted of 12 aquaculture tanks (three replicates per group). The farming benefits were assessed by analyzing variations in the microbial community structure and nutritional composition. The highest dose (T3) produced a higher final body weight than all other treatments (P < 0.05), whereas differences in the remaining growth metrics were not statistically significant (P > 0.05). Supplementation with a higher dose (T3) of R. mucilaginosa allowed its colonization within the biofloc ecosystem, reducing eukaryotic microbial diversity without significantly affecting the prokaryotic diversity. Nutrient analysis showed increased whole-body astaxanthin and higher crude protein as well as essential and flavor amino acids in both bioflocs and shrimp muscle, with the strongest responses at T3 (P < 0.05); crude lipid did not change (P > 0.05). Hepatopancreatic trypsin, lipase, and amylase activities rose with dose, with T3 exceeding the other groups (P < 0.05). Furthermore, the activities of digestive enzymes (trypsin, lipase, amylase) exhibited a dose-dependent increase, with the T3 group showing significantly higher enzymatic activities compared to other groups (P < 0.05). In conclusion, the waterborne inoculation of R. mucilaginosa modulated the biofloc microbial composition, nutrition, and growth of juvenile Penaeus vannamei.

In 2024, Taiwan’s fisheries produced over 1 million tons, valued at more than NT$100 billion, with aquaculture accounting for roughly 40% of total value. While the fisheries sector in Taiwan has a workforce of over 300,000 people, the number of workers has declined by 11.7% from 2004 to 2024, contributing to a critical and ongoing labor shortage. The emergence of smart fisheries alleviates labor pressures but simultaneously demands that aquaculture and fisheries education advance in parallel with these technological developments. This study examines the current status and challenges of fisheries talent cultivation in the context of smart fisheries. It analyzes trends in student enrollment, graduate employment, and curriculum design within fisheries vocational high schools. Adopting a mixed-methods approach, the study combines quantitative government data with qualitative interviews of educators to provide a comprehensive understanding of educational adaptations. Findings reveal significant labor shifts within the fisheries sector, ongoing curricular reforms aimed at incorporating smart technologies, and persistent obstacles to building sustainable workforce development. These results underscore the urgent need for sustained educational investment, stronger industry-academia collaboration, and greater attention to the broader deficiency in ocean literacy to ensure that fisheries education aligns with the evolving demands of Taiwan’s smart fisheries industry.