Aquaculture International最新文献

The growth of cultured fish is influenced by various environmental factors. Understanding the growth performance of fish under different environmental factors can help find a balance between energy consumption and productivity. However, there is limited research on optimizing energy consumption and fish growth under different environmental factors. To address this issue, we focus on the specific growth rate, feed conversion rate, and power consumption of juvenile spotted knifejaw under different temperature and flow velocity conditions. Power consumption across flow velocities was modelled using a linear function to identify the optimal flow rate. Furthermore, a Transformer algorithm is employed to predict power consumption at different temperatures, which is subsequently integrated with the non-dominated sorting genetic algorithm II (NSGA-II) to derive a Pareto front. The ideal point method is then applied to this front to determine the optimal temperature parameter. Experimental results identify the optimal growth temperature and flow velocity for juvenile spotted knifejaw as 26.3 ~ 26.4 °C and 0.5 BL/s, respectively. The proposed EP-Transformer model demonstrates strong predictive performance, with a root mean square error (RMSE) of 0.108 kWh and a coefficient of determination (R²) of 0.978 when predicting the power consumption required to maintain different water temperatures for 1 day. The Transform-NSGA-II model achieves bi-objective optimization, maximizing growth rate and minimizing power consumption costs for juvenile spotted knifejaw. The optimal temperature is selected from the Pareto front by the ideal point method, which provides a practical solution for the efficient rearing of juvenile spotted knifejaw.

Intensified aquaculture practices have increased the vulnerability of farmed fish to infectious pathogens, highlighting nutritional strategies to increase health and reduce antibiotic reliance. Dietary antioxidants such as Nigella sativa (NI) and carvacrol (CA) have shown potential as functional feed additives because of their synergistic effects under bacterial challenge. This study evaluated whether dietary supplementation with NI aqueous extract, CA, or their combination could enhance growth, antioxidant defense, immune function, and disease resistance in Oreochromis niloticus challenged with Aeromonas hydrophila. A total of 120 fish (mean weight 32.28 ± 0.32 g) were randomly assigned to four groups with three replicates per group (n = 30 fish/group, 10 fish/replicate): control, NI (10 g/kg diet), CA (1 g/kg diet), and NI + CA. Fish were fed for eight weeks, followed by experimental infection with A. hydrophila. Growth performance, hematological and biochemical indices, antioxidant enzymes (SOD, GST), lipid peroxidation (MDA), immune parameters (phagocytic activity, myeloperoxidase, total immunoglobulin), and bacterial re-isolation were assessed. Dietary inclusion of NI, CA, or NI + CA significantly improved growth parameters, with the combined group showing the greatest final body weight, weight gain, and specific growth rate, along with a reduced feed conversion ratio. Hematological and biochemical analyses revealed enhanced hemoglobin and leukocyte profiles and favorable modulation of protein, lipid, and glucose metabolism. Supplementation elevated antioxidant enzymes and reduced lipid peroxidation, indicating improved redox balance. Immune assays revealed increased phagocytic activity, myeloperoxidase response, and total immunoglobulin. Following A. hydrophila challenge, the NI + CA group displayed reduced clinical signs, milder lesions, a lower bacterial load, and the highest relative percent survival. Co-supplementation with NI and CA exerted synergistic protective effects across multiple physiological systems, increasing the antioxidant capacity, immune competence, and resistance to bacterial infection in O. niloticus. This study is among the first to demonstrate the synergistic benefits of NI and CA against bacterial challenge in O. niloticus, supporting their application as natural, cost-effective immunostimulants in functional aquafeeds.

This study assessed the protective effects of dietary exopolysaccharide (EPS) against lead (Pb)-induced toxicity in Nile tilapia (Oreochromis niloticus). A total of 180 mono-sex fingerlings (5.43 ± 0.01 g) were randomly assigned to 12 hapas in three cement ponds, divided into four groups in triplicate: a Pb-contaminated control group (50 ppm) and three groups receiving Pb-contaminated diets supplemented with 1%, 2%, or 3% EPS for 56 days. The obtained growth results indicated that EPS supplementation significantly improved growth in a dose-dependent manner (P ≤ 0.001), with the 3% EPS group exhibiting the highest weight gain, specific growth rate, and lowest feed conversion ratio. Nutrient utilization, including protein and energy efficiency, also showed marked improvement. Meanwhile, flesh composition analysis indicated increased crude protein and lipid content with higher EPS levels, while moisture content decreased. Hematological assessments revealed elevated white blood cell counts and reduced mean corpuscular volume in EPS-fed fish, with red blood cell (RBC), hemoglobin (Hb), and hematocrit (Ht) levels remaining unaffected. Liver and kidney biomarkers (AST, ALT, creatinine) significantly decreased, indicating improved organ function. Metabolic indicators such as glucose, glycogen, and triglycerides declined with EPS supplementation, suggesting reduced metabolic stress, whereas antioxidant capacity increased significantly, as evidenced by higher levels of superoxide dismutase (SOD), glutathione (GSH), and total antioxidant capacity, alongside lower malondialdehyde (MDA) levels. Immune parameters (IgM, IgD, lysozyme) were significantly enhanced, while pro-inflammatory cytokine TNF-2α decreased, and IL-1, IL-6, and IL-10 were upregulated. Histopathological and gene expression analyses confirmed the protective effects of EPS, demonstrating restored hepatic and intestinal integrity and regulation of antioxidant and immune-related genes. Lead accumulation in fish muscle significantly decreased and became undetectable at 2–3% EPS levels. Overall, dietary EPS effectively mitigated Pb-induced toxicity in Nile tilapia by enhancing growth, immunity, antioxidant defense, and reducing lead bioaccumulation.

Crossbreeding is a widely used approach in aquaculture to enhance growth, survival, and overall productivity through the exploitation of heterosis. This study evaluated the performance of nine crosses of progeny generation, including three purebred populations (NN, BB, KK) and six reciprocal hybrids (BN, KN, NB, KB, NK, BK), derived from three wild populations (Ninh Thuan: N, Binh Thuan: B, and Khanh Hoa: K) of the ivory snail, Babylonia areolata. Growth (shell length and body weight) and survival were recorded at different developmental stages, ranging from larval (days 10, 16, 26) to grow-out phases (days 120, 180, 240). A linear mixed model was employed to estimate the additive genetic and heterotic contributions of different strains to growth traits across multiple sampling time points. Results showed that hybrid crosses, particularly NB, BK, and KB, consistently outperformed purebred lines across all measured traits and stages. The BK hybrid showed the highest shell length and body weight, reaching 41.6 mm and 11.31 g at day 240, while NB exhibited the highest survival rate (96.41%) at the same stage. Heterosis was positive for most hybrid crosses, with BK recording a maximum of 14.13% in body weight and NB showing 7.02% in survival at grow-out. These outcomes demonstrate the effectiveness of crossbreeding in improving both robustness and growth in B. areolata and suggest that hybrid crosses involving genetically distinct parental populations offer strong potential for future broodstock development. Given the moderate heterotic and additive genetic effects observed among the studied populations, future breeding programs for B. areolata could primarily rely on selecting strains with superior performance, irrespective of genetic diversity considerations. In addition, this study provides valuable insights into the application of intraspecific hybridization as a genetic improvement strategy for marine gastropods and supports the use of heterosis-driven selection in possibly sustainable B. areolata aquaculture.

Aquaponics integrates aquaculture and hydroponics to achieve nutrient recycling and environmental sustainability. However, optimizing microbial interactions and substrate characteristics remains critical for maximizing system efficiency. This study assessed the influence of four substrates, including coir pith, coconut shell charcoal, biochar and medical stone, on system performance and microbial community dynamics within a decoupled aquaponic setup cultivating crucian carp (Carassius auratus) and cherry tomatoes (Lycopersicon esculentum). Comprehensive analyses were conducted on physicochemical parameters, plant and fish growth, microbial community structure, and substrate chemical alterations. Results demonstrated that biochar beds supported more stable pH, lower soluble organic buildup and stronger nitrification signatures with consistent enrichment of ammonia oxidizing archaea (Thaumarchaeota, 29%) and Nitrospira relative to coir beds. Coir pith has high COD and fosters microbial proliferation that depletes effluent nutrients and impairs plant growth, while its cellulose richness supports notable abundances of Hydrogenedentes, Proteobacteria, and Fibrobacteres. The total nitrogen content in medical stone is significantly advantageous, as it has a high relative abundance of nitrospirae. Redundancy analysis revealed significant correlations between microbial community composition and environmental parameters, notably EC and pH (p = 0.02 at genus level, p = 0.04 at phylum level). Fourier-transform infrared spectroscopy indicated a reduction of cellulose-related functional groups in coir pith over time, and coir-based treatments were associated with higher relative abundances of Nanoarchaeota and Omnitrophicaeota compared with biochar-based substrates. Comprehensive analysis concludes that 6-mm biochar demonstrated increased aromaticity, structural stability, and resistance to microbial decomposition, resulting in optimal microbial diversity, with cherry tomatoes showing the most significant increase in fresh weight.

Immunostimulants are increasingly used in aquaculture as potential alternatives to antimicrobials. However, their absorption and subsequent effects on fish health largely depend on the delivery system. Organogel-based delivery systems show promise in controlled release and improved efficacy of immunostimulants. The present study was aimed to evaluate the immune response, haemato-biochemical effects, and gut histology of common carp (Cyprinus carpio) following administration of a novel organogel-based delivery of inactivated Bacillus subtilis. A 45-day feeding experiment was conducted with four treatment groups: T0 (basal feed), T1 (Organogel + B. subtilis), T2 (B. subtilis + Basal feed), and T3 (Organogel + Basal feed). Various immunological parameters and haemato-biochemical indices were measured over time to assess the efficacy of the organogel based delivery of B. subtilis. Histopathological analysis of the gut was performed to observe any tissue changes. Immune gene expression of pro-inflammatory cytokines (IL-1β and TNF-α) and anti-inflammatory cytokine IL-10 was also analysed. Treatment group T1 exhibited a significant time-dependent enhancement in immune parameters, including lysozyme activity, respiratory burst, immunoglobulins, and phagocytic activity, along with improved haemato-biochemical indices (RBC, WBC, haemoglobin, total protein, albumin, and globulin) and reduced glucose levels. Histological observations showed only mild epithelial lifting and vacuolation in T1, while T2 and T3 had minor intestinal alterations. Immune gene expression revealed upregulation of IL-1β and TNF-α with downregulation of IL-10, indicating strong immune activation. To conclude, organogel-based delivery of inactivated B. subtilis effectively enhanced immune competence, metabolic stability, and tissue integrity in common carp. The findings highlight the potential of this delivery approach as a safe, efficient, and sustainable alternative for improving fish health and resilience in aquaculture systems.

Leptin is a key regulator of energy balance and lipid metabolism. Its expression in various tissues in fish  is modulated by dietary factors. Curcumin was added to basal feed at 0.5 and 1% doses and administered for 100 days to Oreochromis mossambicus. A total of 180 fish were assigned at random to nine tanks (650 L), with each tank containing 20 fish, and were given a basic diet during acclimation. Three groups for treatment were also set up, each consisting of three repeats.  Each fish was fed at  3%  body weight per fish on the experimental diets for 100 days. Using quantitative RT-PCR, the present study confirmed for the first time the mRNA expression of leptin and the leptin receptor in tilapia muscle tissue. The relative mRNA expression of leptin and its receptor in tilapia muscle tissue was significantly downregulated by 0.5% curcumin supplementation. Gas chromatography analysis revealed a significant increase in the major n-3 and n-6 PUFAs (polyunsaturated fatty acids) by curcumin. The index of thrombogenicity (TI) value was significantly decreased by curcumin supplementation. The polyene index (PI) value was significantly increased by curcumin supplementation. Lysine, aspartic acid and glutamic acid were the most predominant amino acids as indicated by the amino acid analysis. A significant reduction in the essential amino acid arginine was observed by 0.5 and 1% curcumin supplementation. Curcumin supplementation improved the enzymatic antioxidant capacities of superoxide dismutase and catalase and significantly reduced the lipid peroxidation product (malondialdehyde). The results suggest that curcumin decreases leptin and modulates fatty acid levels and lipid metabolism, and its supplementation in feed has a beneficial effect in terms of nutritional value and general health in tilapia, as indicated by improved antioxidant system.

Evaluating fish school feeding intensity is essential for optimizing feed efficiency, lowering aquaculture production costs, and ensuring healthy fish development in pond culture. Given that fish schools exhibit diverse feeding morphologies with dynamically shifting aggregation patterns in the pond environment, current models struggle to capture the critical spatial relationships between localized feeding hotspots and global distribution characteristics, leading to compromised accuracy. To tackle this issue, a fish school feeding intensity assessment method based on EfficientNetB0-FPSANet is proposed in this paper. At the data preparation phase, input images first undergo a specialized water surface glare removal processing to eliminate overexposed artifacts caused by water surface reflections, followed by random crops and statistical normalization to optimize visual quality and enhance sample diversity. Secondly, the MBConv layer of EfficientNetB0 is redesigned by removing the Squeeze-Excitation (SE), achieving a lighter architecture without compromising efficacy. Meanwhile, the Fusion Pyramid Squeeze-Excitation Attention (FPSA) is appended at the end of EfficientNetB0, which extracts features at varying scales and effectively preserves the local details and global information. Finally, through rigorous testing on actual fish school image datasets, the developed EfficientNetB0-FPSANet model delivers 98.73% assessment accuracy. Our model achieves superior performance with an accuracy improvement of 2.69%, 2.50%, 2.34%, 1.71%, and 1.56% in comparison with other fish school feeding intensity assessment models based on Swin_transformer, ConvNeXt_base, ResNet50, ShuffleNetV2, and DenseNet121, respectively. Experimental results confirm the effectiveness of our approach in accurately assessing fish school feeding intensity in practical aquaculture environments.

The sandfish Holothuria scabra is one of the most commercially valuable sea cucumber species worldwide due to its high market demand. In Sri Lanka, it supports income generation and the livelihoods of coastal communities; however, the nursery phase is often constrained by suboptimal growth and survival rates. This study evaluated the efficiency of biofloc systems as an improved nursery approach for H. scabra. A 6-week nursery trial was conducted under three treatments: biofloc only (T1), biofloc integrated with marine sediments (sandy-muddy; T2), and marine sediments only (T3; control) with triplicate. Nine fiberglass tanks (1500 L) were stocked with 15 juveniles per tank (mean initial weight 1.48 ± 0.11 g). Fishmeal served as the nitrogen source; molasses was added to maintain a C:N ratio of 15:1. Growth performance, water quality, biofloc volume, and microbial community composition were assessed. Final length, weight, and their gains were significantly (p < 0.05) higher in T2 than in T1 and T3. Specific growth rate (SGR) was significantly (p < 0.05) declined in T1 (0.70 ± 0.55% day⁻¹). Survival was 100% in all treatments. Water quality parameters did not differ (p > 0.05) among the three treatments. Total bacteria density was significantly (p < 0.05) higher in T1 and T2 than in T3. Microbial profiling revealed a higher abundance of Bacillus spp. in T1 and T2, whereas Vibrio spp. dominated in T3. In conclusion, the integration of biofloc–sediment proved to be an economically viable sustainable nursery phase for H. scabra juveniles, ensuring higher growth, no mortality and good microbial profile in zero-water-exchange.

Graphical Abstract

Exposure to chronic cold stress has been shown to affect the performance of Nile tilapia, resulting in substantial economic losses during the winter and early spring months. Implementing appropriate and economically viable nutritional strategies has proven to be an effective measure to maintain welfare and ensure satisfactory performance under low-temperature conditions. We evaluated the effects of dietary supplementation with prebiotics mannanoligosaccharides (MOS), β-glucans (BG), and their combination (MOS + BG) on the innate immune response and intestinal morphology of Nile tilapia subjected to prolonged cold stress. Prebiotic supplements significantly improved innate immune function, intestinal health, and some hematological parameters such as neutrophil/lymphocyte ratio, although they did not significantly affect growth performance or blood biochemistry (p > 0.05). The concentration of lysozyme in serum was increased by MOS (p < 0.01), and lysozyme in mucus was increased by MOS and MOS + BG (p < 0.001) compared to the control diet. The combined diet (MOS + BG) increased the respiratory activity of leukocytes (p < 0.01) compared to the diet without prebiotics. Leukocyte phagocytic function and intestinal health were higher (p < 0.01) in fish that received prebiotic supplements than in those that received the control diet. MOS supplementation, alone or in combination with β-glucans, was more effective in stimulating innate immunity and mitigating the adverse effects of cold stress. In turn, supplementation with prebiotics generally contributed to preserving the intestinal integrity of the fish under hypothermic conditions. Strategic administration of prebiotics derived from the yeast Saccharomyces cerevisiae in winter diets may help reduce cold-related mortality and improve economic outcomes in tilapia farming.

Graphical Abstract