Aquaculture International最新文献

We examined the effects of different levels of dietary bile acid (BA) on the growth performance, digestive capability, immune response, antioxidant activity, and intestinal microbiota of Litopenaeus vannamei in a zero water exchange culture system to identify the optimal dietary BA level. A total of 30,000 shrimps, initially weighing 0.33 ± 0.02 g, were fed diets that included 0 (BA0), 0.2 (BA0.2), 0.4 (BA0.4), 0.6 (BA0.6), and 0.8 (BA0.8) g/kg of BA over a 45-day period. The BA0.2 group exhibited the greatest final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR), along with the lowest feed conversion ratio (FCR). According to broken-line regression analysis, the ideal dietary level of BA for L. vannamei was between 0.21 and 0.23 g/kg, based on SGR and FCR. The levels of lipase, trypsin, acid phosphatase, alkaline phosphatase, glutathione peroxidase, and catalase were notably elevated in both the BA0.2 and BA0.4 groups compared with the other groups (P < 0.05). The BA0.2 group exhibited the highest values for both the ACE and Chao indices and showed the highest estimated species richness. According to Shannon and Simpson index analysis, the intestinal flora diversity of shrimp was highest in the BA0.4 group. Supplementation with BAs can enhance the relative abundance of Actinobacteria present in the intestine. In conclusion, dietary addition of 0.21 to 0.23 g/kg BA is optimal for L. vannamei under a zero water exchange culture system.

Vibrio harveyi is a critical pathogen in aquaculture, capable of inducing severe hepatic damage and metabolic disorders in fish. Comprehensive histopathological, biochemical, transcriptomic, and metabolomic analyses were performed to elucidate the impact of oligochitosan supplementation on hybrid grouper subjected to Vibrio harveyi infection. Growth performance analysis demonstrated that V. harveyi infection markedly elevated the hepatopancreas somatic index, whereas this was effectively attenuated by oligochitosan supplementation. Histopathological findings confirmed that oligochitosan supplementation attenuated V. harveyi-induced pancreatic lesions, including hypertrophy, vacuolization, and apoptosis. Biochemical evaluation showed that oligochitosan improved GOT and SOD activities and mitigated oxidative stress by lowering MDA content. Transcriptomic profiling revealed significant enrichment of immune and metabolic pathways, particularly Toll-like receptor signaling and amino acid degradation, as identified by KEGG analysis. qRT-PCR confirmation revealed that oligochitosan intervention attenuated inflammatory signaling by significantly decreasing the transcript levels of IL-8 and TLR-3. Metabolomic analysis revealed substantial alterations in lipid and glycolipid-related metabolites, with KEGG enrichment indicating notable changes in lipid metabolism. Notably, integrated multi-omics correlation analysis revealed that immune-related genes, such as complement component 7b (c7b) and haptoglobin (hp), were positively associated with anti-inflammatory and lipid metabolism–related metabolites, whereas the lipid synthesis gene pancreatic progenitor cell differentiation and proliferation factor b (ppdpfb) showed a negative association with these metabolites. In summary, oligochitosan supplementation mitigated liver damage in hybrid grouper infected with V. harveyi and modulated immune and metabolic responses, highlighting its potential as a functional feed additive in aquaculture.

Traditional manual fish vaccination is labor-intensive, inefficient, and often characterized by poor working conditions. To address these challenges, this study introduces an intelligent fish vaccination system using grass carp as a model species. An improved YOLOv8s model was employed for real-time detection of fish fry. Specifically, the backbone integrates a C2f-DCNv2-MPCA module, which enhances the deformable convolutional structure by replacing parts of the original C2f. The spatial pyramid pooling (SPPF) was upgraded to an AIFI architecture, and an EMA attention mechanism was introduced for better performance. Similarly, an auxiliary bounding box inner-IoU loss function was implemented to optimize both the loss function and the accuracy. Experimental results demonstrate that the improved YOLOv8s-fish model achieves a mAP50 of 95.5%, precision of 95.1%, and recall of 94.8%. These results represent improvements of 1.6, 1.5, and 1.1 percentage points over the baseline YOLOv8s, respectively, and the model operates at a detection speed of 175.4 frames per second (fps). When compared to YOLOv3-tiny, YOLOv5s, YOLOv7, and RT-DETR, the model shows increases in mAP50 of 7.1, 8.2, 2.4, and 3.2 percentage points, respectively. These findings indicate the effectiveness of the improved model for the real-time detection of fry characteristics in complex micro-flow environments and provide valuable technical support for the subsequent design of fish vaccine injection devices.

Microalgae represent a large group of photosynthetic microorganisms that produce a wide range of bioactive compounds as part of their metabolic processes. Many of these molecules have been reported to promote cell adhesion, migration and proliferation, indicating their relevant potential for treating skin injuries. In intensive aquaculture production systems, skin lesions in farmed fish, resulting from aggressive behaviour or suboptimal management practices, could increase their susceptibility to infections and diseases compromising their welfare and overall production efficiency. The present study focused on testing the effects of the green microalga Neochloris oleoabundans whole extract at different concentrations (1:16 and 1:32 dilutions) on cell proliferation and migration in AB9 zebrafish caudal fin fibroblast cells, showing enhanced wound healing after a 30-min treatment in constant darkness (DD; + 5–20% in wound closure in treated cells). As zebrafish cells and tissues are directly light-entrainable and thus, light-dependent reactions in wound healing were expected, we investigated responses to algal extract treatments applied during mid-dark (MD) and mid-light (ML) phases, finding that untreated cells healed faster in ML. These findings provide preliminary insights into the light-dependent effects of microalgal extracts and their potential application in aquaculture wound treatments.

Infectious hematopoietic necrosis (IHN) represents a significant threat to the rainbow trout aquaculture industry, and vaccination constitutes an effective strategy for prevention and control. To elucidate the immunoprotective efficacy of the recombinant IHNV-G protein vaccine in rainbow trout and its regulatory effects on intestinal mucosal immunity and microbiota composition, this study developed the vaccine and performed experimental evaluations using rainbow trout as a model organism. Following a 30-day immunization period, fish were challenged with 5.25 × 10⁶ PFU of IHNV. First, the immunoprotective efficacy of the vaccine was assessed through a challenge experiment. Subsequently, by integrating histopathological examination of intestinal tissues, detection of serum antibodies, analysis of intestinal immunity-related gene expression, and 16S rDNA sequencing of the gut microbiota, the impact of the vaccine on intestinal mucosal immunity and microbial composition was systematically investigated. The results demonstrate that the vaccine achieves a relative protection rate of 63%. Following immunization, serum antibody levels increase significantly, reaching a peak at 28 days post-vaccination. In the vaccine group, intestinal mucosal damage is significantly alleviated, and the structure of the intestinal villi is largely preserved. The expression of genes associated with intestinal immunity (e.g., Muc2, IgT, CD4, MHC II, IFN-γ, and TNF-α) is significantly upregulated. Following challenge, the vaccine group effectively mitigated the decline in intestinal microbial diversity. The abundance of beneficial bacterial taxa, such as Firmicutes and Bacteroidota, was significantly increased, whereas that of opportunistic pathogens, including Spirochaetota and Brevinema, was markedly suppressed (the abundance of Brevinema was only 0.01%, substantially lower than the 85.75% observed in the control group). The above results indicate that the recombinant IHNV-G protein vaccine significantly enhances resistance to IHNV in rainbow trout by stimulating systemic and mucosal immune responses, alleviating intestinal pathological damage, and modulating gut microbial composition. This finding provides an experimental foundation for the development of highly effective IHN vaccines targeting intestinal immunity and microecological regulation.

Clostridium butyricum (CB) has attracted significant scientific investigation in recent years due to its multifaceted probiotic properties. In this 56-day feeding trial, Pelophylax nigromaculatus were fed graded dietary supplementation of CB at six incremental doses: 0 (control, CB0), 1 × 10⁵ (CB1), 1 × 10⁶ (CB2), 1 × 10⁷ (CB3), 1 × 10⁸ (CB4), and 1 × 10⁹ (CB5) CFU/g feed. The results demonstrated that the CB3 and CB4 groups exhibited significantly improved growth metrics and optimized feed efficiency. These improvements were potentially attributable to elevated activities of key digestive enzymes (α-amylase and trypsin) and improved intestinal morphology. Furthermore, intestinal health was markedly strengthened, as evidenced by increased activities of immunomodulatory enzymes (alkaline phosphatase and acid phosphatase), reduced serum markers of intestinal permeability (diamine oxidase, D-lactic acid), and alleviated oxidative stress. Moreover, CB administration markedly reshaped the gut microbial structure, leading to a substantial increase in beneficial bacteria (Bacteroides, Bacillus, Parabacteroides, and Lactococcus lactis) and a reduction in pathogenic genera such as Streptococcus and Corynebacterium. This microbial remodeling was accompanied by a significant elevation in microbial-derived metabolites, particularly short-chain fatty acids, indoles, and bile acids. Transcriptomic analysis suggested that these changes correlated with the upregulation of key genes involved in tight junction integrity pathways, while also contributing to the downregulation of pro-inflammatory cascades such as the complement and coagulation pathways. Collectively, our results indicate that dietary CB supplementation promotes growth and enhances intestinal health in P. nigromaculatus. The beneficial effects appear to be mediated through a coordinated microbiota–metabolite–host transcriptome interaction, which improved barrier function, nutrient assimilation, and immune homeostasis.

This study evaluated the effects of natural calcium carbonate sources, eggshell (ES) and seashell (SS) powders on growth performance, survival, molting frequency, and exoskeletal calcium accumulation in juvenile red claw crayfish (Cherax quadricarinatus). Juveniles (0.21 ± 0.01 g) were reared for 60 days under five treatments (0, 5, 10, 15 mg ES L⁻¹ and 15 mg SS L⁻¹) in a static-water culture system equipped with biofiltration. All groups were fed a formulated diet containing 30% crude protein, 8% crude lipid, and 6% eggshell powder. No significant differences (P > 0.05) were observed in growth performance (2.55–2.65% day⁻¹), FCR (1.55–1.69), or survival (71–78%) among treatments. Nevertheless, there is a trend of improved growth performance with the addition of calcium in water. In addition, molting frequency and carapace calcium content were significantly higher (P < 0.05) at 15 mg L⁻¹ for both ES and SS treatments compared with other treatments. Both calcium concentration in culture water (R = 0.89) and carapace calcium (R = 0.82) exhibited strong positive correlations with molting frequency. While supplementing calcium through the water appeared to have minimal effects on growth and survival once dietary calcium requirements were met, it exerted clear positive effects on molting performance. Considering their abundance and low cost, eggshells therefore represent a practical, affordable, and sustainable calcium source for enhancing molting success in freshwater crayfish culture systems.

This study evaluated the toxicological impact of waterborne boric acid and the protective effects of dietary Nigella sativa (black cumin) oil in Nile tilapia (Oreochromis niloticus). After determining the 96-h LC₅₀ of boric acid (176.446 mg/L), fish were chronically exposed to 1/20 LC₅₀ for 21 days. Hematological analysis revealed significant reductions in RBC, Hb, and Hct in the boric acid group (BA3), indicating anemia and impaired oxygen transport, whereas supplementation with 1% N. sativa oil (BA4) restored these indices toward control levels. Boric acid exposure markedly elevated hepatic enzymes (AST, ALT, ALP) and metabolic indicators (glucose, triglycerides, cholesterol), while BA4 demonstrated hepatoprotective effects by reducing enzyme levels and normalizing serum biochemistry. Oxidative stress assessment showed increased lipid peroxidation (MDA) and reduced antioxidant enzyme activities (CAT, SOD, GPx) in BA3, whereas N. sativa supplementation enhanced antioxidant defense and decreased MDA levels. Histopathologically, boric acid caused severe lesions including lamellar epithelial separation, hepatocyte vacuolization, sinusoidal hemorrhage, renal tubular degeneration, and glomerular congestion. These lesions were substantially attenuated in BA4, with minimal tissue alterations. Collectively, these findings demonstrate that N. sativa oil exerts hematoprotective, hepatoprotective, and antioxidant effects, mitigating boric acid–induced physiological and cellular damage in Nile tilapia, and highlight its potential as a functional dietary additive for sustainable aquaculture.

This study aimed to examine the value chain of sturgeon meat and caviar produced through aquaculture in Azerbaijan, a country with a prominent role in sturgeon farming, and to predict the network’s overall efficiency. Research data were collected via surveys of four sturgeon farms in Azerbaijan and an equal number of value chain actors involved in the delivery of products to consumers. The general characteristics of the sturgeon farms were identified. A value chain map of sturgeon meat and caviar was developed and analyzed using Porter’s model. The network efficiency of the value chain was predicted using the network DEA model. The results showed that sturgeon producers are the most significant contributors to the sturgeon product value chains. However, their value share is low, and negative values were identified for sturgeon meat. Differences in network efficiency scores were found based on market type, indicating that international market value chains have higher network efficiency levels than the domestic market. Implementing a training program focused on the fair distribution of shares in the value chains of sturgeon products, carried out jointly by all actors along the chain, can positively impact the network efficiency and effectiveness of actors at each stage.

The study investigated the impact of sulfate-type saline-alkali water on the growth, feed utilization, histomorphology, and liver inflammation in largemouth bass. Largemouth bass (16.5 ± 0.33 g) were divided into four groups: freshwater (CON), salinity 6‰ with 7 mmol/L alkalinity (S6A7), salinity 6‰ with 10 mmol/L alkalinity (S6A10), and salinity 9‰ with 7 mmol/L alkalinity (S9A7). Each group comprises three tanks, each containing ten fish. The experiment continued for 30 d. The results showed that sulfate-type saline-alkali water significantly reduced specific growth rate (SGR), feed intake (FI), and condition factor (CF) while increased feed conversion ratio (FCR) (P < 0.05). Compared with S6A7 group, SGR and FI were significantly lower in S6A10 and S9A7 groups, and FCR was significantly higher in S6A10 group (P < 0.05). In S6A7, S6A10, and S9A7 groups, swollen gill filaments, damaged intestinal villi, increased renal plasma cells, and signs of renal degeneration, alongside elevated serum ALT levels were observed. Hepatic pro-inflammatory gene (tnf-α, il-1β, il-6, il-8) expression was stable in the S6A7 group (P > 0.05) but significantly increased in S6A10 and S9A7 groups (P < 0.05). The anti-inflammatory genes (tgfβ-1a) were down-regulated in S6A10 and S9A7 groups (P < 0.05). Sulfate-type saline-alkali water also led to marked decline in ghr-β expression and increase in igf-1 expression (P < 0.05). In summary, sulfate-type saline-alkali water inflicts gill, intestine, and kidney damage in largemouth bass, stimulates hepatic inflammation, disrupts the GH-IGF axis, and consequently hampers the growth performance. Our findings offer a potential solution to counteract growth inhibition in fish reared in saline-alkali water, aiming to assist aquaculturists in improving productivity under challenging conditions.