Aquaculture Reports最新文献

In this study, we investigated the growth performance and early sex differentiation in Chinese longsnout catfish (Leiocassis longirostris), and further systematically evaluated its feminization by oral administration of various doses and treatment durations of 17β-estradiol (E₂). Under the same breeding condition, the growth rate of male Chinese longsnout catfish was 20.8 % and 33.9 % faster than that of the female sibling at one- and two-year-old, respectively. The ovarian cavity began forming on 15 dph and completed by 21 dph, while the primary oocytes were at chromatin-nucleolus stage by 33 dph and at the peri-nucleolus stage oocytes by 65 dph. In presumptive testis, the seminiferous lobule appeared on 15 dph and the efferent duct anlage presented on 53 dph. Subsequently, germ cells entered into mitosis and formed the spermatogonia at 69 dph. Compared with the control group (no E2 diet), the fries treated with E2 at 10, 50, 100 or 150 mg/kg diet from 10 to 90 dph were 100 % female by morphology and histology observation. However, the growth and survival rate rapidly decreased as the E₂ dosage rose. Furthermore, fries treated with10 mg/kg E₂ during 15–85 dph, 20–80 dph, 25–75 dph, 30–70 dph, 35–65 dph and 40–60 dph were explored. 3.33 ± 3.33 % and 45.55 ± 5.09 % sex reversal ratio was identified in 30–70 dph and 35–65 dph group, respectively. All female populations were observed in 15–85 dph, 20–80 dph and 25–75 dph groups, despite slow development of ovary among them compared with the control group. Additionally, the growth performance of fries in 25–75 dph group was closest to that of the control group, while their serum E₂ and 11-KT levels were consistent with XX females. Transcriptomic analyses were performed to assess gene expression difference among the XX females, XY males and feminized XY females, and most DEGs were shared between XY male vs XX female and XY male vs XY female. In addition, qRT-PCR validation of 12 DEGs associated with gonadal differentiation were consistent with RNA-Seq analysis (r=0.942, P<0.000). This study suggests that 10 mg/kg E₂ treatment from 25 to 75 dph is the optimal approach for the feminization of Chinese longsnout catfish.

Sea urchins produced by aquaculture could enhance declining wild populations and provide a sufficient roe product to satisfy increasing market demand. This study reports a method for large-scale rearing of the edible tropical sea urchin Salmacis sphaeroides, from induction of larval metamorphosis and settlement, to juvenile rearing and grow-out. Larvae were reared in 500-L hatchery tanks, on a diet of the microalga Chaetoceros muelleri at concentrations ranging from 2500 to 24,000 cells mL⁻¹, with daily water renewal of one-third to two-thirds of the volume depending on their developmental stage. The larvae breeding protocol proved suitable for this species, and competent larvae occurred at 12 days post-fertilization. To induce metamorphosis, we tested exposure to potassium chloride (KCl) at different concentrations (0, 25, 50, 100, 200, and 400 mmol L⁻¹) and for different durations (5, 10, and 20 min). Exposure to 200 mmol L⁻¹ KCl for 5 min resulted in the highest proportion of metamorphosed individuals (41.67 ± 2.89 %). Using this method, the densities of juveniles attaching to settlement plates (232.50 ± 41.23 ind. per plate; settlement percentage ca. 3.88 ± 0.69 %) were approximately twice as high as those of the controls (105.75 ± 15.52 ind. per plate; settlement percentage ca. 1.76 ± 0.26 %). Next, two batches of juveniles were grown out in sea cages. In the first batch (deployed for ca. 4 months), the absolute growth rate of the test diameter (AGR_D) was 12.79 ± 0.98 mm month⁻¹ from May to September; in the second batch (deployed for 6 months), the AGR_D was 5.68 ± 0.90 mm month⁻¹ from October to May of the following year. Survival of the juvenile S. sphaeroides in the sea cages was high (86.56 %–100 %). Finally, the S. sphaeroides cultivated in the second batch were harvested (at a mean test diameter of 71.24 ± 1.45 mm, and wet weight of 101.24 ± 1.91 g) on May 28 of the second year; all animals had matured and could be successfully utilized as broodstock. The fatty acid composition of the gonads was then compared between cultivated and wild-collected adult S. sphaeroides. The proportion of polyunsaturated fatty acids in the cultivated sea urchins (16.59 ± 0.67 %) exceeded that in wild-collected individuals (13.13 ± 0.42 %). From these experiments we conclude that S. sphaeroides is a sea urchin species with excellent potential for aquaculture; the present methods and data will provide helpful information for their mass production in South China.

The effect of dietary niacinamide (NAM) on the growth performance and liver lipid metabolism of swamp eel have been poorly investigated. Therefore, a 120-day feeding trial was conducted to provide different levels of NAM in diet and an untargeted lipidome analysis was performed to address this subject. We found that dietary NAM improved the growth performance of swamp eel. It also decreased the contents of glucose and lipids, including glucose, glycogen, TG, and NEFA, as well as fat accumulation in liver, but increased HDL-C content. We speculated that NAM inhibited lipid accumulation in liver by decreasing the key enzyme activity of LPL, HL and LPS. Fatty acid profile analysis showed that the contents of MUFA and PUFA, such as palmitoleic acid, oleic acid, and eicosapentaenoic acid were significantly increased, while the contents of SFA, such as myristic acid, stearic acid, and palmitic acid were decreased in liver by dietary NAM. Lipidome analysis also indicated that the majority of differential lipid metabolites belonged to glycerophospholipids and sphingolipids, which were enriched in the pathways of insulin resistance, adipocytokine signaling pathway, cholesterol metabolism, fat digestion and absorption, lipid and atherosclerosis, and lipid cell lipolysis regulation. These findings gave scientific evidences and novel insights into the metabolic responses to dietary NAM in swamp eel, and provided basic knowledge for using NAM as a feed additive in swamp eel production.

Management evaluation is essential to optimize finances by increasing egg production, survival rates, larval rearing, and nursery growth. Research aims to analyze production and financial performance in sustainable practices for producing hybrid grouper seeds such as cantang and cantik. The research was carried out for one year, from September 2022 to September 2023. Survey method with the selection of research locations carried out purposively utilized both primary and secondary data types. Primary data was collected through surveys using questionnaires, interviews, and direct observation of activities. Direct observations were conducted at egg production, hatchery, and nursery activities. Research shows that in one year the egg production is 97,300,000 cantang eggs and 17,800,000 cantik eggs. The final length mean harvested in the hatchery was 3.5 ± 0.28 cm with a survival rate of 8.3 ± 4.9 % for cantang hybrid grouper and 3.2 ± 0.25 cm with a survival rate of 10.1 ± 5.0 % for cantik hybrid grouper. The total length of the nursery harvested was 10.9 ± 0.30 cm with a survival rate of 71.5 ± 8.7 % for cantang hybrid grouper, and cantik hybrid grouper measured 10.1 ± 0.30 cm with a survival rate of 81.0±6.0 %. The highest net profit comes from nurseries, followed by larval rearing and egg production. Investments in egg production, larval rearing, and nursery businesses are financially advantageous, as both the R/C and B/C ratios > 1, demonstrating their economic viability. The increasing demand for hatcheries and seeds highlights the importance of successful egg production in fulfilling the growing needs of grouper hatcheries. Nursery operations play a crucial role in enhancing the success of grouper grow-out by improving survival rates and reducing rearing times. They focus on nurturing seeds from their early stages until they reach a suitable size and strength for the grow-out phase.

Fermented Spirulina platensis (FS) has recently attained attraction in human food due to its high functionality and rich content of bioactive compounds. Therefore, the current study investigated the potential roles of dietary FS on the growth performance, digestion capacity, antioxidative status, and immune response of Nile tilapia. Dietary FS at 0, 0.5, 1, 2, 4, and 8 g/kg were fed to Nile tilapia for 60 days. All formulated diets were isonitrogenous and isocaloric with 30.48 % crude protein and 6.63 % total lipids, respectively. The results indicated that the final weight (FW, P=0.004), weight gain (P=0.023), and specific growth rate (SGR, P=0.021) were influenced by dietary FS in a significant quadratic manner. Accordingly, the regression analysis revealed that the suggested doses of FS supplementation in Nile tilapia diets to show the highest FW and SGR are 4.26 and 3.98 g/kg, respectively. Furthermore, dietary FS enhanced the amylase (P=0.035) and lipase (P=0.004) activities in a quadratic manner. The elevated doses of dietary FS instigated prominent improvement of the villous height and goblet cell and increased branching of intestinal villi in the middle segments, particularly in fish fed 4 and 8 g/kg. The red blood cells (P=0.009), hemoglobulin (P=0.004), hematocrit (P=0.034), and white blood cells (P=0.014) were increased significantly with dietary FS in a quadratic manner. No marked effects were seen on the alanine transaminase, aspartate aminotransferase, urea, creatinine, total cholesterol, and triglycerides. Meanwhile, the total protein (P=0.039), albumin (P=0.021), and globulin (P=0.002) were increased significantly by dietary FS in a quadratic manner. The superoxide dismutase (P=0.005) and catalase (P=0.022) were increased, while malondialdehyde level (P=0.028) was decreased significantly with dietary FS in a quadratic manner. The lysozyme activity was higher in fish-fed FS at 0.5, 1, 2, 4, and 8 g/kg than in fish-fed FS at 0 g/kg. The phagocytic activity was higher in fish-fed FS at 2 and 4 g/kg than in fish-fed FS at 0, 0.5, and 8 g/kg without significant differences with fish-fed FS at 1 g/kg (P˃0.05). The regression analysis revealed that the suggested doses of FS supplementation in Nile tilapia diets to show the highest lysozyme activity and catalase activity are 3.52 and 3.79 g/kg, respectively. In conclusion, dietary FS enhanced growth performance, feed utilization, digestive enzyme activity, blood health, immunity, and antioxidative response. Overall, dietary FS can be added at 3.52–4.26 g/kg to enhance the productivity and well-being of Nile tilapia.

The present study aimed to investigate the ameliorative effects of lysolecithin on fish stearin oil, meanwhile comparing the application of two different forms (lysolecithin powder and lysolecithin oil) and three inclusion levels (0.25, 0.75, 1.25 g kg⁻¹) in largemouth bass. The entire study consisted of a 28-day digestibility trial and a consequent 68-day feeding experiment. Eight iso-nitrogenous (∼ 500 g kg⁻¹) and iso-energetic (∼ 22 MJ kg⁻¹) diets with high lipid level (∼ 170 g kg⁻¹) were formulated to contain the same level of two different types of lysolecithin, and namely WFO (130 g kg⁻¹ winterized fish oil), FSO (130 g kg⁻¹ fish stearin oil), LLP (FSO + 1 g kg⁻¹ lysolecithin powder, purity 250 g kg⁻¹), MLP (FSO + 3 g kg⁻¹ lysolecithin powder), HLP (FSO + 5 g kg⁻¹ lysolecithin powder), LLO (FSO + 0.625 g kg⁻¹ lysolecithin oil, purity 400 g kg⁻¹), MLO (FSO + 1.875 g kg⁻¹ lysolecithin oil) and HLO (FSO + 3.125 g kg⁻¹ lysolecithin oil), respectively. Largemouth bass fed FSO showed lower apparent digestibility coefficients (ADCs) of nutrients (total fat, crude protein, gross energy, total amino acid, total essential amino acid) than the WFO. Without considering the lysolecithin type, medium and high doses (0.75, 1.25 g kg⁻¹) significantly increased ADCs of nutrients compared with the 0.25 g kg⁻¹ supplementation level. Lysolecithin oil significantly increased ADCs of nutrients than the lysolecithin powder. Thus, lysolecithin oil was chosen for 68-day feeding trial, and results showed the highest FBW, FI, WGR and SGR were recorded in diet HLO, and significantly higher than the FSO, LLO and MLO. Diet MLO significantly decreased lipid and energy in whole-body and lipid retention compared with the FSO, LLO and HLO. In addition, activity and mRNA expression of adipose triglyceride lipase significantly increased, while glycerol-3-phosphate acyltransferase 4 decreased in diet HLO.

Horseshoe crabs are marine chelicerates which have existed for about 450 million years. Their long coexistence with microbial pathogens presumably is due to their efficient immune system. Herein, the first large-scale transcriptome and microRNA (miRNA) dataset of embryonic stages of the horseshoe crab Tachypleus tridentatus were presented. It provides a general overview of global gene expression changes during horseshoe crab’s early development. This study focuses on the stages 18–20 of the embryonic development of T. tridentatus, which are the first three major embryonic molt stages and involve the formation of several vital organs. We identified 138,260 unigenes, including 34 immune-related gene families such as pattern recognition receptors, signaling and transduction pathway genes, antimicrobial peptides, and coagulation cascade genes. Additionally, 1522 miRNAs (1046 known miRNAs and 476 novel miRNAs) were predicted to 29,584 target genes. Numerous mRNA-miRNA interactions were also identified. Results of Quantitative PCR proved that the immune genes such as Spaetzle, ankyrin-3, peptidoglycan-recognition protein, coagulogen, TNF-receptor-associated factor, and CD-9 antigen were negatively regulated by miR-5735, miR-200, miR-145, miR-199, miR-144, and miR-322, respectively. Futhermore, we confirmed the target regulatory relationship between miR-200 and ankyrin-3 by dual luciferase reporter gene assay. To better understand the complex developmental gene regulatory networks in T. tridentatus, the time-course gene expression data analysis is the first step. Our results provide a valuable resource for analyzing the functions of gene repertoires in embryonic developmental stages （Stage 18 to Stage 20）of horseshoe crab.

Mastacembelus armatus is an important economic fish in China. Since males grow faster and larger than females, breeding monosex M. armatus has great value in the aquaculture industry. Cultivating YY fish is the key to producing genetically all male M. armatus. However, there have been no reports on production of fertile YY supermale, and the production technique of all-male fish has not yet been established in M. armatus. In this study, YY M. armatus offspring were obtained by mating XY pseudofemales with XY males and it was proved that YY fish is sublethal. The offspring were cultured under LE and AS treatment, followed by sex-linked marker screening, to obtain YY pseudofemales and YY supermales, respectively. A portion of YY supermales proved to be viable and fertile, but the fertility of YY pseudofemale still needs further verification. Subsequently, by mating XX females with YY supermales and performing AS treatment on their offspring, mass production of genetically all male M. armatus could be achieved. For the first time, YY M. armatus was confirmed to be able to survive and has obtained fertile YY supermale fish. In addition, marker assisted selection (MAS) technique was established to produce genetically all male fish (GM) in M. armatus (MAS-GM technique). This is expected to significantly increase the yield and economic benefits of the M. armatus aquaculture industry. Beyond that, YY fish provides useful material for understanding the sex determination mechanism of M. armatus. In summary, MAS-GM technique can achieve the all-male breeding of M. armatus, laying the foundation for the development of standardized M. armatus farming.

Infectious myonecrosis virus (IMNV), first identified in 2003, predominantly infects the shrimp species Litopenaeus vannamei and has caused significant economic losses in major shrimp farming regions in Brazil and Southeast Asia. However, the infection mechanisms of IMNV has not been elucidated. In this study we have investigated the molecular mechanisms of IMNV-shrimp interaction and identified potential antiviral key genes to provide a theoretical reference for developing new control technologies. Transcriptome sequencing of control and infected shrimp groups at 30 (early), 60 (mid), and 90 days (late) post-infection identified 695, 2411, and 401 differentially expressed genes (DEGs), respectively. Early infection analysis revealed IMNV promotes colonization and spread by inhibiting hemagglutination and apoptosis-related genes while activating antiviral pathways like JAK-STAT, indicating it evades host defenses by interfering with the innate immune response. During mid-stage infection, glucose and amino acid metabolism pathways were enriched, suggesting IMNV induces host metabolic reprogramming to support viral replication. Late-stage analysis showed downregulated apoptosis and autophagy pathways, and upregulated cytoskeleton and extracellular matrix genes, indicating the host mitigates viral tissue damage by regulating cell fate and repair mechanisms. This transcriptomics study uncovers dynamic shrimp gene expression changes induced by IMNV infection, identifying multiple immune and metabolic pathways involved in the antiviral response. It elucidates IMNV's pathogenic mechanism and identifies key regulatory genes in pathways like PI3K-Akt-mTOR and JAK-STAT. These findings enhance our understanding of IMNV-shrimp host interaction and could inform novel antiviral strategy development.

The aim of this experiment was to investigate the effects of dietary lycopene (LCP) on growth performance, antioxidant, and immunity of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) fed with high-lipid diets (HLD, CL16 %). Hybrid groupers (20.56±0.17 g) were selected and fed four diets containing 0, 100, 200 and 400 mg/kg of LCP, named L0, L1, L2 and L3. The results showed that: FBW and SGR were significantly higher in all dietary LCP group compared to the L0 group (P< 0.05). In serum, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) content were significantly higher in group L2 than in group L0, and alkaline phosphatase (AKP) content in L3 group was significantly lower (P< 0.05). In the liver, malondialdehyde (MDA) content were significantly lower in all LCP groups than in the L0 group (P< 0.05); catalase (CAT), AKP, and acid phosphatase (ACP) activities were significantly higher in all LCP group than in the L0 group (P< 0.05); SOD, Aspartate aminotransferase (GOT) and glutamate-pyruvate transaminase (GPT) activities in the liver were significantly higher in the L2 group than in the L0 group (P< 0.05). Dietary supplementation of 200–400 mg/kg LCP significantly up-regulated mRNA levels of hepatic sod, gsh-px, cat, nuclear factor erythroid 2-related factor 2 (nrf2), heat stimulating protein 90 (hsp90) and transforming growth factor-β (tgfβ), and significantly down-regulated mRNA levels of hepatic kelch-like ECH-associated protein 1 (keap1) and interleukin-1β (il1β) (P< 0.05). The optimal levels of LCP were 282.22 mg/kg, 246.83 mg/kg and 248.5 mg/kg for FBW, serum GSH-Px activity and hepatic immunoglobulin M (IgM) content, respectively. In conclusion, the addition of 200–300 mg/kg LCP could promote the growth performance of hybrid grouper, improve the antioxidant capacity, and alleviate the oxidative damage of liver caused by HLD.