Aquaculture Research最新文献

Probiotics and spirulina are used to improve health, growth, and immunity of fish. The purpose of this study was to evaluate the effects of water additive probiotics and dietary Spirulina platensis on growth (weight gain (WG) and specific growth rate (SGR)), hematobiochemical parameters (hemoglobin (Hb) and blood glucose (Glu)), intestinal histology, and genes (growth hormone (gh) in pituitary and insulin-like growth factors: igf-1 and igf-2 in liver) expression profiles of Nile tilapia (Oreochromis niloticus). Nile tilapia was distributed to three treatment groups: Control (no probiotics or spirulina), Probiotic (probiotics 1.0 mL/L in water), and Spirulina (Spirulina platensis, 50 g/kg feed), each with three replicates for 42 days. Fish supplemented with probiotic and spirulina exhibited significantly higher (p < 0.05) WG (21.66 ± 2.92 g and 25.63 ± 3.92 g, respectively) and SGR (2.30 ± 0.16 and 2.18 ± 0.14%/day, respectively) than the control group. Hb and blood Glu levels showed negligible variation (p > 0.05) among the groups. The abundance of mucus producing goblet cells (GCs) was highest in fish reared with probiotic and spirulina treatments compared to the control group. Relative mRNA levels of gh in the pituitary were expressed profoundly (p < 0.05) in fish reared with probiotics and spirulina treatments compared to the control group. Relative mRNA levels of igf-1 in the liver expressed significantly higher (p < 0.05) in the fish fed with spirulina, whereas the relative mRNA levels of igf-2 expressed significantly higher (p < 0.05) in the fish subjected to probiotic treatment than control group. Principal component analysis (PCA) also supported the influence of probiotic and spirulina regarding growth performance over control treatment. These findings showed that probiotic and spirulina positively affect growth by improving intestine morphology and activating the GH/IGF axis in Nile tilapia.

It has been reported that phenylalanine (Phe) or tyrosine (Tyr) supplementations significantly affect fish stress and welfare biomarkers. The objective of this study was to determine the amount of Phe/Tyr in the diet and feeding time necessary to mitigate stress. Seabreams (Sparus aurata) were stocked at 5 kg m⁻³ in 500 L tanks. The experimental treatments consisted of different types of feeding: control, Phe-enriched (5%, 7.5%, 10% on dry food), and Tyr-enriched (5%, 7.5%, 10%) food for 2, 4, or 8 days each. At the end of each experimental treatment, fish were sampled for blood, and 10 fish from each treatment were previously subjected to stress by exposure to air (3 min) and sampled 30 min and 2 h later. Plasma glucose, lactate, proteins, cortisol, adrenaline, and noradrenaline concentrations were measured. Dietary Tyr supplements led to high mortalities in long treatments (8 days). The best results for attenuating stress biomarkers were found for the 10% Tyr supplements for 4 days since this treatment kept the maximum number of stress biomarkers with no significant changes. The correlations between biomarker concentrations and amino acid (AA) concentration/supply time were not always significant, though it seems that Tyr supplements present more consistent effects, the increase in Tyr concentration or feeding period being related to decreasing biomarker concentrations.

Exogenous amino acid supplementation has become a nutritional strategy to improve the tolerance of whiteleg shrimp (Litopenaeus vannamei) to a high proportion of vegetable protein diets. In the present study, the effects of glycine in high-proportion fermented soybean meal (FSBM) feed for shrimp were verified. SBM fermented by Bacillus subtilis was used to replace 50%, 75%, and 100% of fish meal (FM), respectively. Concomitantly, 1% glycine was added to the diets containing FSBM. After an 8-week feeding trial, FSBM substitution significantly inhibited the growth parameters of shrimp, including weight gain rate (WGR) and specific growth rate (SGR). Glycine supplementation significantly alleviated the inhibition of growth performance induced by 50% FSBM substitution but not in the 75% and 100% FSBM substitution groups. Glycine significantly increased the level of glycine in the muscle. In addition, glycine supplementation improved the structure of hepatopancreas and increased the length of sarcomeres and myofiber density in muscle tissue. RT-qPCR results revealed that glycine inhibited the mRNA expression of smyhc1 and smyhc2. Further investigation revealed that glycine enhanced the antioxidant capacity in muscle tissue and inhibited the mRNA expression of immune genes, including traf6, toll, and lgbp, caused by FSBM substitution. In summary, the results indicated that appropriate glycine supplementation could ensure that 50% FSBM substitution of FM did not affect the growth performance of shrimp. Moreover, glycine may improve the structure of muscle tissue by enhancing antioxidant capacity and immunity. This study further emphasized the crucial role of glycine in the development of low FM feed for shrimp.

This study investigates the synergistic effects of swimming activity and dietary restriction on the metabolic and nutritional characteristics of muscle tissue in juvenile rainbow trout (Oncorhynchus mykiss, Walbaum, 1792). During a 6-week study, four groups of juvenile rainbow trout, each starting with an average weight of 26.54 ± 0.36 g, were analyzed: the first group was allowed to feed freely in static water (SW group), the second experienced a dietary limitation (25% feed restriction) (LF group), the third was required to swim at a speed of one body length per second (SE group), and the fourth group faced a combination of dietary restriction (25% feed restriction) and enforced swimming activity (SELF group). Swimming activity was implemented using a water flow rate of one body length per second (1 BL s⁻¹), ensuring a standardized exercise intensity. Comprehensive analysis revealed significant alterations in biochemical parameters, amino acid composition, and fatty acid profiles in rainbow trout muscle tissue. The results indicate a decrease in histidine levels (p  < 0.05) with the combined effect of both swimming and feeding restrictions. Additionally, cysteine and semi-essential amino acids (EAAs) showed a decrease (p  < 0.05) solely due to the influence of swimming. As for fatty acid outcomes, linolenic acid exhibited a reduction with the combined impact of both swimming and feeding restrictions (p  < 0.05), while margaric acid significantly decreased (p  < 0.05) only with the influence of swimming. Crucial shifts in antioxidant defense mechanisms, including glutathione (GSH) and lipid peroxidation (LPO) levels, were identified, highlighting the roles of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) as biochemical parameters. Detailed examination further clarified modifications in glucose-6-phosphate dehydrogenase (G6PD) activities, reactive oxygen species (ROS) levels, and lactate dehydrogenase (LDH) activity, serving as pivotal indicators of oxidative stress and tissue damage. These findings contribute to a holistic understanding of nutritional dynamics within rainbow trout muscle tissue, offering insights crucial for optimizing fish health and productivity in aquaculture.

This study revealed the affecting mechanism of trash fish (TF) and compound feed (CF) on the flesh quality of largemouth bass (Micropterus salmoides) based on muscle transcriptome. Largemouth bass weighing 75.0 ± 0.1 g were given TF or CF for a period of 12 weeks. The CF group presented significantly higher feed efficiency (FE) than the TF group (p < 0.05), while there was no significant difference in specific growth rate (SGR) between the two groups (p > 0.05). A total of 604 differentially expressed genes (DEGs) meeting the significance criteria of p-value < 0.05 and |log2foldchange| > 1 were identified in the muscle transcriptome analysis. Compared to the TF group, 145 DEGs were downregulated, and 459 DEGs were upregulated in the CF group. Enrichment analysis of Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways revealed significant enrichment of 401 GO terms and 13 pathways, respectively. In the CF group, there was a notable increase in gene expression in pathways such as arachidonic acid (AA) metabolism, protein processing in the endoplasmic reticulum, cholesterol metabolism, MAPK, and focal adhesion, while there was a decrease in pathways like purine metabolism, apoptosis, glycolysis/gluconeogenesis, and PPAR signaling. Real-time fluorescence quantitative PCR results indicated decreased expression of tni (troponin I, fast skeletal muscle-like) and increased expression of stni (troponin I, slow skeletal muscle-like), ftni (troponin I, fast skeletal muscle), mustn1b (musculoskeletal, embryonic nuclear protein 1b), actn2b (alpha-actinin−2), and hspb1 (heat shock protein [HSP] beta 1) in the CF group compared to the TF group. Overall, according to transcriptomics, replacing TF with CF altered the gene expression related to meat and the associated signaling pathways, leading to the meat quality improvement for largemouth bass.

This study assessed the impact of dietary Chenopodium album leaf powder on various aspects of Nile tilapia (Oreochromis niloticus), including growth performance, hematological and biochemical profiles, antioxidant status, nonspecific immune response, and resistance to Aeromonas hydrophila infection. A 60-day feeding trial was conducted with 180 Nile tilapia fingerlings, with an initial average weight of 11.79 ± 0.23 g, fed diets supplemented with increasing levels of C. album at 0, 10, 20, and 30 g/kg. After feeding, the fish underwent an experimental challenge with the pathogen A. hydrophila. Following the challenge, the fish survival was monitored for 14 days. The results demonstrated that as the level of C. album supplementation increased, there were significant (p  < 0.05) improvements in growth performance and a reduction in the feed conversion ratio (FCR). The hematological and biochemical profiles showed significant (p  < 0.05) enhancements in the groups that received C. album-supplemented diets. Additionally, the antioxidant status in the fish serum significantly (p  < 0.05) improved, as evidenced by increased activities of superoxide dismutase (SOD), catalase (CAT), and reduced glutathione. The nonspecific immune response, including lysozyme activity, phagocytic activity, and fish survival, also exhibited significant (p  < 0.05) enhancements, particularly in the groups receiving 20–30 g/kg of C. album. Furthermore, there was a significant decrease in serum glucose and cortisol levels in the groups fed with 20–30 g/kg of C. album. In conclusion, C. album supplementation at 20–30 g/kg improved growth, immune response, and disease resistance in Nile tilapia. This diet also reduced stress markers, enhancing overall health.

This study explores the effects of synbiotics on growth, intestinal health, and immunity in the Asian fossil catfish (Heteropneustes fossilis), a crucial species in Southeast Asian aquaculture. With the rising use of antibiotics in aquaculture, which poses risks to both the environment and consumer health, there is an urgent need for sustainable alternatives. This study investigates how synbiotics—combinations of probiotics and prebiotics—can enhance fish health and performance. Four dietary treatments with varying synbiotic concentrations (0%, 4%, 6%, and 8%) were tested over 45 days. Results indicated that synbiotic supplementation significantly improved growth metrics, including final weight and specific growth rate (SGR), with the highest benefits observed at 8% inclusion. Additionally, dietary synbiotics enhanced intestinal health by increasing villi height and width and crypt depth and positively affected hematological parameters, notably elevating hemoglobin (Hb) levels. Histological analysis revealed improved liver tissue organization and hepatocyte morphology with higher synbiotic concentrations. These findings suggest that synbiotics offer substantial benefits for fish growth, health, and immunity, positioning them as a viable, ecofriendly alternative to antibiotics in aquaculture. Further research should aim to refine synbiotic formulations and investigate their underlying mechanisms to optimize their application in sustainable aquaculture practices.

This study investigated the immune responses induced in gibel carp, Carassius auratus gibelio, following immersion and intraperitoneal (i.p.) vaccination with live attenuated Cyprinid herpesvirus 2 (CyHV-2). Transcriptome sequencing analysis was performed on the kidney tissues of the experimental fish at 3, 7, and 14 days postvaccination. A staggering 948 million readings were assembled into 96,891 genes, with an average length of 1214 bp. We analyzed the KEGG enrichment, differentially expressed genes (DEGs), and DEGs temporal expression patterns between the immersion and i.p. injection groups. Our findings revealed that both i.p. injection and immersion vaccination significantly altered immune-related genes in gibel carp, suggesting that the prepared attenuated vaccine effectively stimulates the fish’s immune response. Generally, the injection group exhibited higher gene expression levels in the kidney tissue earlier and to a greater extent. In contrast, the immersion group showed delayed immune responses with lower expression levels. The differential expression of 12 immune-related genes in immunized gibel carp, as detected by real-time quantitative PCR. Significant differences were observed in the expression of 12 immune-related genes after vaccination, suggesting variations in the sensitivity of each gene to bodily stimuli and its involvement in immunity. The specific immune mechanisms require further research. These results provide essential data for evaluating vaccines’ immune pathways and efficacy, offering optimism for vaccine development in fish immunology.

Ascidians are marine sessile animals that are particularly abundant on artificial structures, where they often overgrow native species and compete with other filter feeders. North Carolina’s (NC) coastline supports productive aquaculture operations and ascidians are considered pests there. Five shellfish farms and four nearby marinas were surveyed to compare the structure and composition of their ascidian communities using photo-quadrat surveys and presence–absence and abundance matrices, with “marina” and “shellfish farm” as factors. Twelve species were observed in the marinas, but only six in the farms: three native, two cryptogenic, and one identifiable only to the genus level. The three native species (Clavelina oblonga, Perophora viridis, and Molgula manhattensis) have established populations in many world regions and were observed in at least two of the farms visited. The cryptogenic Styela plicata was found in all farms and marinas and was the most abundant species. All species observed in shellfish farms were also present in marinas, with no significant difference in ascidian composition or abundance. Independently of introduction status, species thriving in a wide range of habitats are more adaptable and better suited to establish populations on artificial substrates, resulting in increased maintenance costs for aquaculture operations.

Open sea cage culture has become a major trend in mariculture, with strong wind resistance, wave resistance, anti-current ability, high degree of intensification, breeding density, and high yield. However, damage to the cage triggers severe economic losses; hence, to adopt effective and timely measures in minimizing economic losses, it is crucial for farmers to identify and understand the damage to the cage without delay. Presently, the damage detection of nets is mainly achieved by the underwater operation of divers, which is highly risky, inefficient, expensive, and exhibits poor real-time performance. Here, a remote-operated vehicle (ROV)-based autonomous net detection method is proposed. The system comprises two parts: the first part is sonar image target detection based on NanoDet. The sonar constantly collects data in the front and middle parts of the ROV, and the trained NanoDet model is embedded into the ROV control end, with the actual output of the angle and distance information between the ROV and net. The second part is the control part of the robot. The ROV tracks the net coat based on the angle and distance information of the target detection. In addition, when there are obstacles in front of the ROV, or it is far away from the net, the D-STAR algorithm is adopted to realize local path planning. Experimental results indicate that the NanoDet target detection exhibits an average accuracy of 77.2% and a speed of approximately 10 fps, which satisfies the requirements of ROV tracking accuracy and speed. The average tracking error of ROV inspection is less than 0.5 m. The system addresses the problem of high risk and low efficiency of the manual detection of net damage in large-scale marine cage culture and can further analyze and predict the images and videos returned from the net. https://youtu.be/NKcgPcej5sI.