Aquaculture Research最新文献

Daphnia carinata is an important biological live feed in aquaculture. Conventionally, D. carinata is cultivated and fed with fresh Chlorella pyrenoidosa, which is inconvenient for storage and transportation. After undergoing vacuum freeze-drying or spray-drying, C. pyrenoidosa exhibits advantages such as reduced weight and easier storage and transport. This study investigated the effects of feeding freeze-dried and spray-dried Chlorella on the reproductive performance and fatty acid composition of D. carinata. The results indicated that there was no significant difference in reproductive performance between the two groups of D. carinata fed with freeze-dried Chlorella and fresh Chlorella. However, a significant decline in reproductive performance was observed in the group fed with spray-dried Chlorella. The contents of crude fat and unsaturated fatty acids in freeze-dried Chlorella were significantly higher than in spray-dried Chlorella. Additionally, D. carinata fed with freeze-dried Chlorella exhibited significantly higher levels of unsaturated fatty acids (especially ALA and EPA) than those fed with spray-dried Chlorella. In conclusion, freeze-dried Chlorella can be used as an alternative to fresh Chlorella for cultivating D. carinata. Unsaturated fatty acids are a key factor influencing the reproductive performance of D. carinata.

The Macrobrachium genus thrives in freshwater and brackish environments. M. hainanense, a nocturnal freshwater prawn, is economically significant in China due to its delicious meat and rich nutrition. Its distribution is limited to regions like Zhejiang, Guangdong, Guangxi, Fujian, and Hainan due to breeding habits near estuaries and low-temperature tolerance. Despite its economic importance, there are limited studies on M. hainanense, particularly regarding its germplasm resources. This study investigates the growth traits, nutritional composition, enzyme activity, and genetic diversity and structure of seven M. nipponense populations and three M. hainanense populations to inform sustainable aquaculture and conservation efforts, comparing them with the new hybrid varieties of M. nipponense, which successfully cultivated, Because of its fast growth, high adaptability, and strong reproductive capacity was chosen as a control sample due to its well-established quality, economic value, reputation, ensuring competitive comparison. The amino acids, fatty acids, and physiological and biochemical indicators among M. hainanense populations and M. nipponense populations showed significant differentiation. M. hainanense populations showed minor differences in nutritional components except for total sugar and astaxanthin content that were significantly different, whereas M. nipponense populations showed almost no differences. Essential amino acids in M. hainanense comprised 34.42%–37.53% of the total amino acid content. Differences in glycine, isoleucine, and cystine were notable in M. hainanense, while glycine and proline differed in M. nipponense. Fatty acid components varied among the populations studied. Genetic diversity analysis revealed that the polymorphism information content (PIC) values for M. hainanense were higher than those for M. nipponense. The Changhua River (CH) and Nandu River (ND) populations of M. hainanense had the lowest nucleotide diversity, while the Oujiang River (OU) population had the highest. The OU population also exhibited the greatest genetic diversity, with the lowest inbreeding coefficient, while the CH population had the highest. There was slight genetic differentiation among M. hainanense populations, with geographical isolation and artificial selection contributing to genetic structure differences. This study is the first to examine population-wide genetic variability in M. hainanense, highlighting the need for comprehensive conservation and breeding strategies to maintain and enhance genetic variability in this species. The study concludes that both M. hainanense and M. nipponense have rich protein content and low-fat content, with varied genetic relationships and differentiation among populations.

A pathology characterized by multifocal reddish patches on the cuticle of shrimp has been reported by shrimp farmers in Latin America. These red patches are commonly associated with small black necrotic spots and white muscle necrosis. One significant impact of this pathology is the reduction in shrimp prices due to the appearance of the animals before and after cooking. The disease is more prevalent in areas with salinities above 5 ppt, with one farm reporting a 45% incidence in one pond. Histopathological examination revealed infiltration of hemocytes in the muscle tissue, melanosis, muscle necrosis, and the presence of Gram-negative rods in the muscle tissue. Given the presence of bacteria and negative polymerase chain reaction (PCR) results for muscle-infecting viruses such as infectious myonecrosis virus (IMNV) and Penaeus vannamei nodavirus (PvNV), this pathology is likely due to bacterial infection, though environmental stressors cannot be ruled out as contributing factors in this complex condition. Several Vibrio strains were isolated from the affected tissue and identified using API 20E and PCR. Two strains were selected for in vivo experimentation: Vibrio parahaemolyticus (C8Cg, PirAB toxin-positive) and V. alginolyticus (C3Ver, PirAB toxin-negative). Shrimp injected with both live and autoclaved bacteria showed similar histopathological changes, suggesting that the pathology is due to virulence factors within the bacterial cells that can still provoke a strong immune or toxic response even in the absence of live, actively replicating bacteria.

Recently, there has been increasing attention regarding the potential application of biodegradable nanoparticles (NPs) as adjuvants in injectable vaccines. In this study, encapsulated antigens of Aeromonas hydrophila in alginate/chitosan polymers were used as injectable vaccines in common carp. Formalin-killed bacteria and extracellular products (ECPs) of A. hydrophila were encapsulated via emulsification method. In total, 480 juvenile common carp (32.1 ± 3.64 g, mean ± SD) were randomly divided into eight triplicate groups (20 fish for each replicate). Groups 1–3 were injected with bacterin, ECP, and bacterin + ECP, respectively. Groups 4–6 were injected with encapsulated bacterin, encapsulated ECP, and encapsulated bacterin + ECP, respectively. Groups 7 and 8 as controls were injected with alginate/chitosan and phosphate-buffered saline (PBS), respectively. Blood samples were collected on days 0, 30, and 60 of the experiment. Immunological parameters, including antibody titer against A. hydrophila, serum lysozyme, bactericidal and complement activities, and nitro blue tetrazolium (NBT) reduction, as well as serum globulin and protein levels, were compared among the groups. Hematological parameters (red blood cell [RBC], white blood cell [WBC], hemoglobin [Hb], and hematocrit (Hct) were evaluated too. Remained fish were challenged with severe A. hydrophila, and mortality was recorded for 10 days. Results showed that anti-A. hydrophila antibody titer, survival rate following bacterial challenge, NBT reduction, serum lysozyme activity, globulin, and protein levels were significantly higher in encapsulated bacterin and encapsulated bacterin + ECP groups compared with the control group (p  < 0.05). Serum bactericidal and complement activity showed no significant change in different groups of sampling points. Then, it can be concluded that the encapsulation of bacterin and bacterin + ECP of A. hydrophila using chitosan/alginate NPs enhanced the protection and immune responses in common carp and this method is a promising candidate for a vaccine adjuvant in fish.

In this study, the effects of using the distiller’s dried grains with solubles (DDGS) instead of soybean meal on rainbow trout (Oncorhynchus mykiss) were investigated. Four different experimental diets were prepared with isonitrogenous (43%) and isolipidic (19%) values, incorporating DDGS at levels of 0%, 10%, 20%, and 30%. Fish were weighed (18.5–20.2 g) and randomly distributed in 12 tanks (140 L water) with 22 fish in each tank. The feeding trial lasted 60 days and was conducted in triplicate. The best weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR) were observed in the DDGS20 experimental group. While viscerosomatic index (VSI) and hepatosomatic index (HSI) values were found to be the highest in the DDGS30 experimental group, the spleen-somatic index (SSI) was found to be the highest in the DDGS10 experimental group (p  < 0.05). It was found that the nutrient digestibility ratio values and fish meat chemical composition values of the experimental diets were similar between the groups (p  > 0.05). Additionally, it was analyzed that the use of DDGS protein sources in diets did not negatively affect the coloration of the experimental fish. While DDGS percentage increased in the diet, hepatocyte nucleus diameter was decreasing (p  < 0.05). In the distal intestine, the DDGS10 and DDGS20 groups gave results that are more likely to be digestible, which depends on villi length. The results of the DDGS30 groups had no negative effects on both liver and distal intestine. The genes interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin 8 (IL-8), and superoxide dismutase 2 (SOD2) exhibited higher fold changes when DDGS2 contribution was present in the liver, whereas the interleukin 1 beta (IL-1β) gene exhibited lower fold change. Furthermore, the mean fold changes increased with the proportion of the DDGS additive in the immunoglobulin M (IgM) heavy chain and immunoglobulin T (IgT) genes but decreased in the catalase (CAT) and glutathione peroxidase 1 (GPX1) genes. TNF-α and SOD2 genes showed the lowest fold changes in the head kidney in the presence of DDGS20, whereas IL-1β and GPX1 genes exhibited the highest fold changes in the presence of DDGS10. Moreover, the utilization of feed additives extracted from DDGS in feed formulations resulted in cost reductions, thereby positively influencing the production cost per kilogram of feed. Among the trials, the incorporation of DDGS20 had the most beneficial impact on the cost per kilogram of fish due to its comparatively lower cost.

Excessive feed input led to eutrophication and Cyanobacterial blooms in the culture of giant freshwater prawn (GFP, Macrobrachium rosenbergii). In order to improve the water quality and control the Cyanobacterial blooms, we tried the mixed culture of oriental river prawn (ORP, Macrobrachium nipponense), which can feed on plant and organic debris. In this study, the culture trial began on June 20th and ended on September 10th. The control group (CG) was GFPs monoculture, while the experimental group (EG) cultured GFPs and ORPs. Water samples were collected from the ponds for five times to compare the changes of water environmental factors and phytoplankton communities in CG and EG. Phosphate, nitrite, sulfide, and ammonia nitrogen in CG were significantly higher than those in EG at the end of culture (p < 0.05). In the middle stage of culture, the Margalef index, Pielou index, and Shannon–Wiener index of EG were significantly higher than those of CG (p < 0.05). The biomass and density of phytoplankton in EG were lower than those in CG, and the occurrence of Cyanobacterial blooms in EG was later. The results indicated that ORPs in the mixed culture model effectively transformed and stored part of the energy by consuming the residual bait, which reduced the degree of eutrophication and Cyanobacterial blooms.

The biofloc technology (BFT) in sea cucumber (Apostichopus japonicus) farming utilizes nutrient cycling, driven by heterotrophic microorganisms, to improve water quality and promote sustainable aquaculture. This study explored the potential of sodium bicarbonate and sodium acetate as novel carbon sources, which may offer advantages in maintaining water stability and enhancing microbial diversity compared to traditional carbon sources. Juvenile sea cucumbers were cultured in a 64-day trial and assigned to five treatment groups: S (sucrose), SSa (S + sodium acetate), SSb (S + sodium bicarbonate), Nc (no carbon source), and Cg (control group), each treatment group was repeated three times (n = 3). The inclusion of sodium bicarbonate and sodium acetate significantly improved water quality parameters. The group SSb exhibited a higher pH (8.28), and significantly lower ammonia nitrogen (0.501 mg L⁻¹), and nitrite levels (0.031 mg L⁻¹) compared to other groups. Additionally, the biofloc volume (BFV; 17 mL L⁻¹), total suspended solids (TSSs; 238 mg L⁻¹), and protein content (13.9%) in the group SSb were all within the tolerance range for sea cucumbers. Group SSb also showed the significantly highest weight gain rate (WGR; 78.5%) and specific growth rate (SGR; 0.91%), alongside increased enzyme activities, including superoxide dismutase (SOD; 179 U mL⁻¹) and peroxidase (POD; 1.59 U mL⁻¹), which were significantly higher than those in other groups. Furthermore, the group SSb demonstrated enhanced gut microbiota diversity, characterized by a higher abundance of beneficial Bacillus and lower levels of harmful Vibrio and Pseudomonas. The addition of SSb significantly improved water quality by maintaining optimal pH and reducing harmful nitrogen compounds, which in turn supported enhanced physiological growth and increased gut microbiota diversity, indicating its potential as a superior carbon source in biofloc systems.

The present study assessed the effect of common hop (Humulus lupulus L.) extract on common carp (Cyprinus carpio L.). Fish (initial weight of 32.22 ± 0.65 g) were divided into three groups and fed diets containing 0 (control), 0.75 g (H_0.75), and 1.5 g (H_1.5) of common hop extract per kg of isonitrogenous, isolipidic, and isoenergetic commercial diet for 8 weeks. No significant differences in growth performance across treatments were observed (p > 0.05). Protein content in whole-body proximate composition increased significantly in H_1.5 compared to the control (p < 0.05). The H_0.75 showed a significant increase in lipid peroxidation (LPO) and reduced glutathione (GSH) levels compared to the control (p  < 0.05). While H_1.5 had higher acetylcholinesterase (AChE) than group H_0.75 (p  < 0.05), no significant change was observed in AChE, catalase (CAT), and superoxide dismutase (SOD) activities in treated groups compared to the control (p  > 0.05). Blood biochemical indices, alanine aminotransferase (ALT), and alkaline phosphatase (ALP) were significantly lower in H_0.75 and H_1.5 than in the control (p < 0.05), while lactate dehydrogenase (LDH) increased significantly in H_1.5 compared to the control (p < 0.05). Cholesterol, triglyceride (TG), and the number of white blood cells (WBCs) showed no significant differences across treatments (p > 0.05). H_0.75 significantly increased the proportion of polyunsaturated fatty acids (PUFAs) like α-linolenic acid, docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA; p < 0.05), and both H_0.75 and H_1.5 raised considerably the value of oleic acid and eicosatrienoic acid compared with the control (p < 0.05); in contrast, eicosapentaenoic acid (EPA) was decreased significantly by H_1.5 compared to the control (p < 0.05). Supplementation of the common hop at 0.75 and 1.5 g kg⁻¹ positively affected farmed carp.

This article presents the recent advancements in recirculating aquaculture systems (RAS). The review explores new developments and potential future breakthroughs in RAS systems across leading countries. It highlights technical and technological advancement in plant management aimed at improving water quality, production efficiency, and animal welfare. A significant aspect of recent progress is the integration of artificial intelligence (AI), which is being used to optimize system performance, enhance monitoring, and support more precise and predictive management strategies. The review also addresses advancements in pathogen control and the prevention of disease outbreaks. Specific case studies of cutting-edge RAS systems from different parts of the world are discussed. The review also investigates how the improvements in RAS technology can help mitigate environmental impact. Finally, the paper focuses on advancements in the production of six fish species farmed in Europe, namely Atlantic salmon (Salmo salar), European seabass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), yellowtail kingfish (Seriola lalandi), arctic charr (Salvelinus alpinus), and rainbow trout (Oncorhynchus mykiss). This review is part of the ERA-NET BlueBio cofound-funded project titled “Optimizing land-based fish production in next generation digital recirculating aquaculture systems,” which is focusing on the above-mentioned fish species.

This study examines the dietary application of probiotic Bacillus licheniformis and phytobiotic Cinnamomum verum concerning growth, immunity, gene expression, and disease resistance in Labeo rohita fish. A controlled experiment was conducted over 12 weeks involving 800 fingerlings, which were divided into seven groups: one control group and three groups each receiving varying doses of B. licheniformis (D1 = 10⁵, D2 = 10⁷, and D3 = 10⁹ CFU/g) and C. verum (D4 = 25, D5 = 50, and D6 = 75 mg/kg) individually, along with a group with no additions (control). Growth was measured in terms of weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) alongside hematology and immunology. To evaluate resistance of the test organisms, pathogenic challenge with Aeromonas hydrophila was performed. The findings indicated that fish in the D3 group achieved the highest average final weight of 125.40 ± 0.1 g, a weight increment of 86.40 ± 0.53 g, and the most favorable FCR of 0.81 ± 0.01. The D6 group followed, in contrast to the control group, which had a body weight of 95.20 ± 0.2 g, a WG of 56.73 ± 0.05 g, and a FCR of 1.03 ± 0.06. The survival rates following the challenge were analyzed, revealing that group D3 exhibited the highest effectiveness (p < 0.001). The evaluation of immunological parameters in D3 indicated increased levels of total protein, immunoglobulin M (IgM), complement component 3 (C3), and lysozyme activity relative to D1 and D2. Analysis of gene expression revealed that interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) were upregulated in the liver and head kidney tissues of fish in the D3 and D6 groups. Bacillus licheniformis, when administered at 10⁹ CFU/g, enhances growth, feed utilization efficiency, immunity, and disease resistance in L. rohita. Cinnamomum verum at a dosage of 75 mg/kg improved the immune response. This study supports the consumption of probiotics and phytobiotics as substitutes for antibiotics in aquaculture.