Epinephelus Fuscoguttatus Research Articles

Host Gut-Derived Probiotic, Exiguobacterium acetylicum G1-33, Improves Growth, Immunity, and Resistance to Vibrio harveyi in Hybrid Grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂).

Several exogenous probiotics are applicable in fish culture; however, challenges in isolation and verification have hindered the full utilization of numerous host probiotics. Therefore, this study aimed to apply the host probiotic Exiguobacterium acetylicum G1-33 to hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) cultures and explore its mechanism of action. In total, 360 hybrid grouper were divided into four groups, which were fed the following for 60 days: three received commercial feed with varying concentrations of E. acetylicum G1-33 (106, 108, and 1010 CFU/g), while a control group received commercial feed. The results showed that supplementation with 106 and 108 CFU/g of E. acetylicum G1-33 enhanced gut morphology, upregulated growth-related genes (ghr1, igf-2, s6k1, tor), and promoted growth, with supplementation with 108 CFU/g resulting in the most notable enhancement. However, supplementation with 1010 CFU/g inhibited growth, possibly because of changes in intestinal morphology. Additionally, supplementation with E. acetylicum G1-33 upregulated the expression of immune-related genes (c3, myd88, Cu/Zn-sod, tlr3, and tnf2) in the liver and head kidney but led to an increase in malondialdehyde content, as well as a decrease in alkaline phosphatase and acid phosphatase activities, in the liver and serum, indicating increased oxidative stress. Moreover, supplementation with 106 and 108 CFU/g E. acetylicum G1-33 enhanced the widespread expression of immune-related genes in the head kidney and liver, respectively, and improved resistance to Vibrio harveyi, whereas supplementation with 1010 CFU/g weakened this resistance. In conclusion, E. acetylicum G1-33, particularly at 108 CFU/g, emerged as an effective probiotic, optimizing growth performance and immunity in hybrid grouper. This research is pioneering in its application of E. acetylicum in mariculture, potentially broadening the range of probiotic strategies in aquaculture.

Oleic acid enriched diet affects the metabolome composition of the hybrid grouper infected with vibriosis.

This study focuses in investigating the fatty acid contents of surviving infected hybrid grouper fed with oleic acid immunostimulant. After a 6-week feeding trial, Epinephelus fuscoguttatus × Epinephelus lanceolatus fingerlings were infected with Vibrio vulnificus. One week after bacterial challenge, fish oil was extracted from body tissue of surviving infected fingerlings using the Soxhlet extraction method. The extracted samples were then sent for GC-MS analysis. The raw GC-MS data were analyzed using software programs and databases (i.e., MetaboAnalyst, SIMCA-P, NIST Library, and KEGG). A total of 39 metabolites were putatively identified, with 18 metabolites derived from the fatty acid group. Our further analysis revealed that most metabolites were highly abundant in the oleic acid dietary samples, including oleic acid (4.56%), 5,8,11-eicosatrienoic acid (3.45%), n-hexadecenoic acid (3.34%), cis-erucic acid (2.76%), and 9-octadecenoic acid (2.5%). Worthy of note, we observed a greater abundance of α-linoleic acid (15.57%) in the control diet samples than in the oleic acid diet samples (14.59%) with no significant difference in their results. The results obtained from this study revealed that surviving infected hybrid grouper expressed more immune-related fatty acids due to the effect of oleic acid immunostimulant. Therefore, in this study, we propose oleic acid as a potential immunostimulant in enhancing fish immunity in aquaculture industry.

Effects of aflatoxin B1 on subacute exposure of hybrid groupers (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂): Growth, liver histology, and integrated liver transcriptome and metabolome analysis

With the increasing incorporation of plant-based ingredients into the grouper diet, the issue of aflatoxin B1 (AFB1) contamination in the diet has become a significant concern. In this study, the negative effects of AFB1 on the growth and liver health of hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) were investigated in the context of growth, liver histology, serum biochemical indices, and integrated transcriptomic and metabolomic data. A total of 540 healthy hybrid groupers, initially weighing 11.59 ± 0.03 g, were randomly divided into six groups (three replicates of 30 fish each): the Control group was fed a basal diet, and the experimental groups were supplemented with 7 (AF7), 30 (AF30), 111 (AF111), 445 (AF445) and 2230 μg/kg AFB1 (AF2230) in the basal diet respectively, for 56 days. Groups Control, AF445, and AF2230 were selected for subsequent histological, muscle fatty acid, and transcriptomic and metabolomic analyses based on the results of hybrid grouper growth and serum biochemical indices. Compared to the Control group, both whole-body crude lipid and muscle crude lipid contents showed significant decreases in the AF2230 group (P < 0.05), while only muscle crude lipid content showed a significant decrease in the AF445 group (P = 0.001). Liver damage was seen in the histology of the liver of AF445 and AF2230 groups. Muscle fatty acid results showed that the addition of 445 and 2230 μg/kg AFB1 to the ration increased saturated fatty acids and monounsaturated fatty acids and decreased polyunsaturated fatty acids and highly unsaturated fatty acids in muscle (P < 0.05). Transcriptome analyses revealed multiple metabolic pathways associated with AFB1 metabolism, and metabolomics analyses further confirmed changes in the activity of these pathways. The results of the combined transcriptomic and metabolomic analyses indicated that AFB1 causes liver injury mainly by affecting liver retinol metabolism, metabolism of xenobiotics by cytochromes P450, drug metabolism-cytochromes P450 and biosynthesis of unsaturated fatty acids. In conclusion, dietary AFB1 levels above 445 μg/kg resulted in growth inhibition, liver injury, liver AFB1 accumulation, and reduced muscle polyunsaturated fatty acid content in grouper, thereby affecting muscle quality. This study provides novel insights into the detrimental effects of AFB1 on aquatic species and contributes to the scientific basis for the health and sustainability of aquaculture practices.

Identification and characterization of four Bacillus species from the intestine of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂), their antagonistic role on common pathogenic bacteria, and effects on intestinal health

As an alternative to the criticized antibiotics, probiotics have been adopted for their eco-friendly nature and ability to enhance host growth and immunity. Nevertheless, reports suggest ineffectiveness in commercially available probiotics since most are from non-fish sources; thus, this study was envisaged to isolate and characterize new Bacillus spp. from the gut of hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) which could serve as potential probiotics. The isolation and characterization were performed based on their morphological and biochemical properties, and 16S rRNA sequencing homology analysis. A subsequent 30-day in vivo biosafety feeding trial was conducted to ascertain isolates' non-pathogenicity, as well as their effects on fish growth, and intestinal mucosal microvilli via scanning electron microscopy (SEM) analysis. Four Bacillus spp. strains, namely, B. velezensis strain PGSAK01 (accession number OQ726606), B. stercoris strain PGSAK05 (accession number OQ726607), B. velezensis strain PGSAK17 (accession number OQ726601), and B. subtilis strain PGSAK19 (accession number OQ726605), were identified and characterized in the current study. The strains showed promising probiotic properties such higher adhesion capability, higher thermotolerance, displaying higher survivability to 0.5 % bile, lower pH tolerance, γ-haemolytic activity, and multispecies characteristics. Among the 24 antibiotics tested, while all isolates showed susceptibility to 21, the PGSAK01 strain showed resistance to furazolidone antibiotics. None of the isolates showed possession of i) virulence factor genes encoding enterotoxigenic (hblA, hblC, hblD, nheA, nheB, and entFM) and emetic (cereulide synthetase gene, ces) genes, and ii) streptomycin resistance gene (vat c), ampicillin-resistant genes (mecA and bla), and vancomycin-resistant gene (van B). Nevertheless, the PGSAK01 and PGSAK17 strains showed possession of tek K, cat, and ant(4′)-Ia (adenylyltransferase) (except the PGSAK01) resistant genes. All isolates displayed better antimicrobial effects against pathogenic bacteria Streptococcus agalactiae, S. iniae, Vibrio harveyi, and V. alginolyticus. The in vivo biosafety trial involved hybrid grouper fish being grouped into five (average weight 32 ± 0.94 g), namely, the group fed the basal diet void of isolate's supplementation (control), and the remaining four groups fed the basal diet with 1 × 108 CFU/g diet of individual strain PGSAK01, PGSAK05, PGSAK17, and PGSAK19 supplementation. At the end of the study, a significantly higher WGR, K (except the PGSAK01 group), VSI; lysozyme (except PGSAK01 group), total antioxidant activity, alkaline phosphatase, superoxide dismutase enzyme activities; highly dense intestinal mucosal villi (based on the scanning electron microscopy analysis); and significantly lower malondialdehyde levels were witnessed in the isolated treated groups compared to the control, supporting the results obtained in the auto-aggregation and cell-surface hydrophobicity test. This work's results have provided thought-provoking targets; thus, studies involving extensive genome sequencing and functional annotation analysis will be explored to offer unfathomable insights into their mechanisms of action and potential health benefits, further establishing the four Bacillus strains' (PGSAK01, PGSAK05, PGSAK17, and PGSAK19) potential role in probiotic fields and functional foods.

Comparative Transcriptome Analysis of the Hypothalamic-Pituitary-Gonadal Axis of Jinhu Grouper (Epinephelus fuscoguttatus ♀ × Epinephelus tukula ♂) and Tiger Grouper (Epinephelus fuscoguttatus).

Jinhu groupers, the hybrid offspring of tiger groupers (Epinephelus fuscoguttatus) and potato groupers (Epinephelus tukula), have excellent heterosis in fast growth and strong stress resistance. However, compared with the maternal tiger grouper, Jinhu groupers show delayed gonadal development. To explore the interspecific difference in gonadal development, we compared the transcriptomes of brain, pituitary, and gonadal tissues between Jinhu groupers and tiger groupers at 24-months old. In total, 3034 differentially expressed genes (DEGs) were obtained. KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analyses showed that the osteoclast differentiation, oocyte meiosis, and ovarian steroidogenesis may be involved in the difference in gonadal development. Trend analysis showed that the DEGs were mainly related to signal transduction and cell growth and death. Additionally, differences in expression levels of nr4a1, pgr, dmrta2, tbx19, and cyp19a1 may be related to gonadal retardation in Jinhu groupers. A weighted gene co-expression network analysis revealed three modules (i.e., saddlebrown, paleturquoise, and greenyellow) that were significantly related to gonadal development in the brain, pituitary, and gonadal tissues, respectively, of Jinhu groupers and tiger groupers. Network diagrams of the target modules were constructed and the respective hub genes were determined (i.e., cdh6, col18a1, and hat1). This study provides additional insight into the molecular mechanism underlying ovarian stunting in grouper hybrids.

Effects of Dietary Multi-Strain Probiotics on Growth Performance, Antioxidant Status, Immune Response, and Intestinal Microbiota of Hybrid Groupers (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂).

This study aims to examine the effects of the mixture of Bacillus cereus G1-11 and Exiguobacterium acetylicum G1-33, isolated from the gut of hybrid groupers (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂), on the host. The hybrid groupers were divided into a control (C, without any probiotics), B. cereus (BC, 1010 cfu/g), E. acetylicum (EA, 108 cfu/g), compound (mix, a 1:1 mixture of B. cereus and E. acetylicum), and positive reference group (P, Lactobacillus acidophilus, 5 × 108 cfu/L). Each group had four replicates, with 30 fish per replicate (53.30 ± 0.50 g), and were fed for 60 days. The results showed that adding probiotics to the feed significantly improved the weight gain, weight growth rate, specific growth rate, and digestive enzyme activities of hybrid groupers compared to the C group. The compound group was the most significant. In addition, composite probiotics added to feed significantly upregulated the expression levels of several growth-related genes in the liver and muscles. The activities of alkaline phosphatase, catalase, glutathione peroxidase, glutathione transferase, lysozyme, and total antioxidant capacity in the serum and liver were significantly influenced through mixed probiotic feeding. Moreover, the expression levels of several immune-related genes in the liver, spleen, and head kidney were significantly enhanced by adding single and mixed probiotics to feed, with the synergy of mixed probiotics being the best. An analysis of the gut microbiota showed that adding composite bacteria enhanced the richness and diversity of the gut microbiota, significantly increasing the relative abundance of potential probiotics (Cetobacterium and Microbacterium) while decreasing the presence of potential pathogens (Mycoplasma). Overall, our findings highlighted the efficacy of mixed probiotics (B. cereus and E. acetylicum) in enhancing growth performance, nutritional value of hybrid grouper feed, antioxidant capacity, immune response, and intestinal health, in finding the best combination of functional feed additives.

Case Study: Growth Performance and Business Analysis of Brown-Marbled Grouper (Epinephelus fuscoguttatus) in Nursery and Grow-Out Cultivation

Grouper fish, particularly the brown-marbled grouper (Epinephelus fuscoguttatus), are among the most economically significant marine species widely farmed and exported. This study aimed to analyze the growth performance and business analysis of the production of brown-marbled grouper, both in nursery and grow-out segments. The research was conducted using a case study method at a governmental production and research center located in Lampung Province, Indonesia. Primary data were collected through field observations, while secondary data were obtained from interviews with farm personnel. The study revealed that the nursery phase faced significant challenges, with larval survival rates as low as 4.2%. In contrast, survival rates improved considerably in larger fish, demonstrating better resilience as they grow (reaching 92-93%). From a business perspective, the grow-out activity was found to be more profitable due to lower investment costs. However, it requires a longer period to raise the fish to market size. Both nursery and grow-out operations proved to be profitable, with respective R/C ratios of 1.6-2.0. Overall, while grouper farming is economically viable, it requires careful management to overcome the high mortality in the early life stages and to optimize the investment cost-effectiveness of the nursery phase.

Application of eDNA metabarcoding in the assessment of fish biodiversity in Philippine mangroves: Challenges and opportunities

Biodiversity assessments are important in designing mangrove conservation and restoration programs. In the Philippines, conventional biodiversity assessment methods (e.g., trap nets, fish visual census) can be time-consuming, labor-intensive, and expensive. In recent years, environmental DNA (eDNA) metabarcoding has been an emerging tool for rapid biodiversity monitoring as it is fast, non-intrusive, and can provide broader detection of fauna. But, it is still subject to various field sampling and laboratory analysis constraints. Here, we applied the eDNA metabarcoding method to document and assess fish biodiversity in mangroves from two biogeographic regions in the Philippines: Oriental Mindoro in the West Philippine Sea and Sorsogon in the Northern Philippine Sea. Using 12S genetic markers from eDNA water samples, we detected 89 fish species from 44 families. Only twelve species were commonly detected in both sites. Several species were found in the Philippines’ list of economically important aquatic organisms while one species (Epinephelus fuscoguttatus) was classified as Vulnerable in IUCN’s Red List of Threatened Species. Seventy-six percent more species were detected in Sorsogon probably because the sampling sites were within a seascape of mangroves, seagrasses, and coral reefs. In contrast, the lesser species detected in Oriental Mindoro could probably be because of the more limited sampling points to coastal fringes. Our results serve as baseline data and the first obtained using this method in the country. However, we observed some limitations that should be addressed to improve the method: (1) lack or absence of a comprehensive reference database specific to Philippine aquatic organisms; (2) low eDNA reads which could be attributed to insufficient on-site filtration due to turbid seawaters common in Philippine mangroves; and (3) possible cross-contaminations that can affect comparative analyses. Despite these limitations, we were able to demonstrate the usefulness of this technique in doing rapid assessments which could address knowledge gaps in Philippine mangrove biodiversity studies and contribute to its conservation programs.

A comparative analysis of growth and nutritional quality of the hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) in a simulated pond system and a recirculating aquaculture system

Groupers, as a popular economic fish species, are now more frequently cultured in land-based facilities, however, traditional pond-farming methods are plagued by frequent disease outbreaks, unstable economic benefits, and environmental pollution. To explore a new farming mode for a grouper, an 80-day cultivation experiment was conducted using both a simulated pond system (SPS) and a recirculating aquaculture system (RAS). The research aims to evaluate the growth performance, health (pathogenic bacteria, intestinal microbiota), off-flavor compounds (geosmin, 2-methylisoborneol), and nutritional component (amino acids, fatty acid composition and content) of a hybrid grouper (Pinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) under different aquaculture systems. The results showed that the hybrid grouper in a RAS exhibited better growth performance; the concentration of Vibrio in the fish tissue in the RAS was significantly lower than that in the SPS. Moreover, the content of fresh amino acids in the RAS was significantly higher, and the levels of saturated fatty acids (SFAs) and ω-6 polyunsaturated fatty acids (ω-6PUFAs) were significantly higher in the RAS. This finding indicates the superior flavor and nutritional value of the grouper. These results prove that the RAS is suitable for the widespread cultivation of grouper.

KARAKTERISTIK IKAN KERAPU DI PASAR ARUMBAI AMBON

Arumbai Market in Ambon City, Maluku Province, is a central hub for the trade of fishery products, particularly groupers. This study aims to describe the origin of grouper catches and to identify the species and sizes of groupers marketed at Arumbai Market. Groupers, which belong to the family Serranidae, are the primary predators in coral reef ecosystems. Fish identification was conducted based on Allen's guide and verified through FishBase. The study was conducted from December 2022 to February 2023 using a survey method through direct observation and interviews. Data were analyzed descriptively and presented in tables and graphs. The results showed that groupers at Arumbai Market come from four main locations: Manipa (34.47%), Liang (26.81%), Latuhalat (24.26%), and Pulau Tiga (14.47%). Eight dominant species of groupers in this market are Variola albimarginata (44.64%), Cephalopholis miniata (20.60%), Epinephelus fasciatus (12.45%), Epinephelus ongus (6.44%), Cephalopholis urodeta (6.44%), Cephalopholis sonnerati (5.58%), Epinephelus areolatus (3.00%), and Epinephelus fuscoguttatus (0.86%). Grouper sizes vary, with Cephalopholis miniata having a maximum size of 27.1 cm and a minimum size of 19.9 cm. This study provides essential information on the origin of catches, species dominance, and sizes of groupers marketed, which can serve as a basis for better fishery management. These findings indicate a significant potential for grouper trade in the region and highlight the importance of sustainable management to preserve the continuity of coral reef ecosystems and grouper populations.

Functional genomic characterization reveals the probiotic tendency and safety assessment of Exiguobacterium acetylicum G1–33 isolated from the gut of the hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

Probiotics are commonly used as nutritional supplements and antibiotic substitutes and thus are of great commercial interest. The present study was performed to demonstrate the probiotic potential of Exiguobacterium acetylicum G1–33 isolated from the gut of the hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) by integrating genomics and phenotypic traits. In silico genome analysis confirmed its identity as E. acetylicum. Functional annotation of the genome revealed the existence of molecular markers responsible for the functional properties of potential probiotics, such as resistance to the host’s harsh gastrointestinal environment, adhesion and colonization of the intestinal mucosa, competition and inhibition of pathogens, responses to oxidative stress, and biosynthesis of essential amino acids and vitamins. The genomic analysis was validated by in vitro experiments. Effective toxin-encoding genes were not identified in the G1–33 genome, and the safety of the strain was confirmed by in vitro experiments. These results indicate that E. acetylicum G1–33 exhibits excellent probiotic properties and can become a probiotic with high application value in aquaculture.

Response signatures of intestinal microbiota and gene transcription of the pearl gentian grouper to Vibrio harveyi infection

Vibrio harveyi causes high mortality and severely limits grouper culture. The gut microbiota is an important biological barrier against pathogen invasion. In this study, we investigated dynamic changes in the intestinal microbial community, gene transcription and immune responses signatures of pearl gentian grouper (Epinephelus fuscoguttatus♂ × Epinephelus lanceolatus♀) at 0, 3 and 7 days (referred to as d0, d3 and d7 groups, respectively) after infection with V. harveyi. The results demonstrated that the d7 treatment reduced the gut microbial diversity and increased the proportion of Proteobacteria and Cyanobacteria. Notably, several putative pathogenic genera (Sphingomonas and Bacteroides) proliferated, while putative probiotic genera (Rhodococcus and Lactobacillus) reduced, and these changes in intestinal bacteria might be correlated to the alterations of host immune-related molecules. The d3 and d7 treatments also altered the histomorphology and gene transcription profiles mainly associated with immune function in intestine, such as ‘MAPK signaling pathway’, ‘Apoptosis’ and ‘Toll-like receptor (TLR) signaling pathway’. Furthermore, d3 group induced a homeostatic dysregulation of the antioxidant system, cytokines and TLR signaling, with a tendency to gradually return to a normal state in d7 group, along with the apoptosis process. The pathogenic infection suppressed the expression of JNK pathway and enhanced the ERK pathway. In conclusion, the dysbiosis of the intestinal bacterial communities caused by the immune changes that occurred during V. harveyi infection disrupted the intestine health in the pearl gentian grouper. These results provided a comprehensive understandings of the immune defense mechanisms in fish and valuable references to develop disease control strategies in grouper aquaculture.

Suitable dietary Myo-inositol supplementations improve growth, immunity and antioxidant properties of hybrid grouper (Epinephelus. fuscoguttatus♀ × E. lanceolatus♂) fed low-fishmeal diets

A six-week feeding trial was carried out to evaluate the effects of different dietary Myo-inositol (MI) levels on growth, feed efficiency, immunity, and antioxidant properties of juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) fed low-fishmeal diets. Seven experimental diets were made to contain 50, 100, 169, 241, 309, 386, and 459 mg/kg of MI (analyzed values, dry matter basis), being abbreviated as MI-50, MI-100, MI-169, MI-241, MI-309, MI-386, and MI-459, and each MI treatment had three replicates. Twelve fish (average initial body weight: 18.7 ± 0.1 g) were allocated to each replicate, being hand-fed their diets to apparent satiation on 8:00 am and 16:30 pm. The results indicated that within the range of 50–241 mg/kg dietary inositol, weight gain percentage (WG%), feed efficiency (FE) and protein efficiency ratio (PER) were increased with the increasing of MI, and above the 241 mg/kg, they were dropped, especially at 386 and 459 mg/kg. According to the broken-line regression analysis conducted to assess the relationship between WG% and dietary MI levels, the optimum MI dose was 267.9 mg/kg (dry weight) in the low-fishmeal diet of hybrid grouper. Condition factor (CF), viscerosomatic index (VSI), hepatosomatic index (HSI), and intestinal index (ISI) were significantly (P < 0.05) affected by dietary MI levels, varying with a similar trend as WG%. Fish fed MI-241 had the highest values of serum lysozyme (LZM), hepatic total antioxidant capacity (T-AOC) as well as the relative mRNA level of hepatic insulin-like growth factor-Ⅰ (IGF-Ⅰ) among all treatments. In conclusion, optimum dietary MI requirement for the maximal growth of hybrid grouper was 267.9 mg/kg, and suitable dietary MI supplementations improve growth, immunity, and antioxidant properties of juvenile hybrid grouper fed low-fishmeal diets.

Supplementation of Extender with Melatonin Improves the Motility, Mitochondrial Membrane Potential, and Fertilization Ability of Cryopreserved Brown-Marbled Grouper Sperm.

Sperm cryopreservation is a valuable tool for breeding, conservation, and genetic improvement in aquatic resources, while oxidative damage will cause a decline in sperm quality during this progress. Melatonin (MT), a natural antioxidant hormone, is used as an additive in sperm cryopreservation to reduce cellular damage from oxidative stress. Here, we aimed to investigate the effect of adding MT to the freezing medium in sperm cryopreservation of brown-marbled grouper (Epinephelus fuscoguttatus). Different concentrations of MT (0, 0.1, 0.25, and 0.5 mg/mL) were tested. We evaluated sperm motility, viability, apoptosis, mitochondrial membrane potential (MMP), and fertilization ability to assess the effects of MT supplementation. Our results demonstrated that the addition of MT to the extender improved the post-thaw motility, MMP, and fertilization ability of brown-marbled grouper sperm. The total motility, curvilinear velocity, straight linear velocity, and average path velocity in MT-treated groups (0.1 and 0.25 mg/mL) exhibited significantly higher values than that of the control group. A higher MMP (p < 0.05) was observed in the group treated with 0.25 mg/mL MT, suggesting that supplementation of MT in the extender might be able to protect mitochondrial membrane integrity effectively. Regarding fertilizing ability, 0.25 mg/mL MT yielded a significantly higher hatching rate than the control. An adverse effect was found with the concentration of MT up to 0.5 mg/mL, suggesting the possible toxicity of a high-dose addition. In this study, we optimized the sperm cryopreservation protocol of brown-marbled grouper, which might be valuable for sperm cryopreservation and sample commercialization of groupers and other fish.

Acute hypoxia and reoxygenation alters glucose and lipid metabolic patterns in Hulong hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

Dissolved oxygen (DO) is crucial for fish's biological functions, affecting metabolism, growth, and survival. Intensive aquaculture and live fish transportation, prevalent in the growing live fish market, often expose Hulong hybrid groupers (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) to acute hypoxic stress. This study explores the impact of acute hypoxia and subsequent reoxygenation on these groupers, focusing on their metabolic response and the underlying mechanisms in different tissues. By inducing acute hypoxic stress until mobility loss and then allowing recovery to normal DO levels, we comprehensively assessed glycolipid metabolism using RNA-seq to map regulatory networks in stress and recovery phases. This revealed significant transcriptional regulation related to hypoxic stress and glycolipid metabolism, with pathways like Insulin, HIF-1, FoxO, and cAMP playing key roles. Gill and brain tissues showed rapid changes, with significant upregulation in genes like irs, pi3k, hif-1α, and hk, whereas the liver had a more subdued response, upregulating genes linked to glycolipid metabolism like gdpd5 and amy1. During reoxygenation, lipid metabolism genes were downregulated in gills and brain, while the liver showed enhanced lipid oxidation, upregulating genes like apoa1 and fabp3, suggesting a metabolic shift from anaerobic to aerobic processes. These findings illuminate the molecular mechanisms of grouper adaptation to DO fluctuations, offering insights to mitigate acute hypoxia damage in aquaculture.

Long- and short-term dietary β-glucan improves intestinal health and disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀).

β-Glucans are immunostimulants and are widely used in aquaculture industry. The present study was conducted to evaluate the effects of different periods of β-glucan management on growth performance, intestinal health, and disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). A commercial feed was used as control diet (CD), and the β-glucan diet (βD) was based on CD and further supplemented with 0.1% β-glucan. Grouper in control and long-term β-glucan diet (LGD) groups were fed with CD and βD for 8 weeks, respectively. Groupers in short-term β-glucan diet (SGD) group were fed with CD for the first 4 weeks and βD for the last 4 weeks. We found that LGD and SGD had no effect on growth performance but reduced the mortalities of grouper after challenging with Vibrio harveyi. In addition, both LGD and SGD increased intestinal morphology, enhanced antioxidant capacity, enhanced immunity, inhibited apoptosis, altered the transcriptional profile, and activated mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling pathway in the intestine of grouper. Furthermore, the effect of LGD on most of the above parameters was comparable to that of SGD. In conclusion, LGD and SGD did not affect growth rate parameters but enhanced the intestinal health and disease resistance of pearl gentian grouper.

Bubu Sebagai Alat Tradisional Penangkap Ikan Yang Efektif dan Ekonomis Bagi Nelayan

Bubu is a non-selective fishing gear that the types of fish caught were varied, especially demersal. From several fishing gears, bubu are high economic value so that the demand for fishery resource products is increased by it. The purpose of this study was to determine the construction of fishing gear, composition, and effectiveness of fish caught using bubu. This research conducted in March-April 2022 at Tanjungpandan Nusantara Fishery Port (PPN) Belitung Regency. Descriptive analysis used in this method by interviewes with fisherman who used bubu. Determination the number of respondents using the census method with total number interviewed as many as 46 fisherman. Methods to determine the effectiveness of bubu fishing can be seen from the type of main catch, production per trip, fishing area, and gear construction. The results obtained from this study are that the bubu has a fishing gear construction consisting of a body frame using wood and rattan, mouth frame using wire height with of 100-155 cm, lenght of 60-165 cm, width of 20-85 cm and has an outer mouth diameter of 30-50cm, mouth width of 10-25 cm, while the inside diameter of mouth is 20 cm with mesh size of 3 cm. There are 14 types of fish caught in the bubu, such us Siganus guttatus, Gnathanodon speciosus, Lethrinus letjan, Epinephelus fuscoguttatus, Abalites stellatus, Lutjanus vittus, Caesio cuning, scarus ghoban, Epinephelus areolatus, Diagrama pictum, Lutjanus erythropterus, Plectropanus leoparius, Sphyaerana baraccuda, Carangoides plagiotaenia. The composition of main catch catch is 99.75%, by catch 0.25%. The effectiveness of trap fishing gear gets a score of 80%. So that the use of traps has been effective for use

Combined effects of hypoxia and ammonia-N exposure on the oxygen consumption, glucose metabolism and amino acid metabolism in hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂).

This study evaluated the influence of hypoxia and ammonia-N co-exposure on oxygen consumption, glucose metabolism and amino acid metabolism in hybrid grouper. The results showed that elevated expression of GLUT1, MCT1, PFK, HK and LDH were induced by co-exposure to hypoxia and ammonia. In addition, co-exposure to hypoxia and ammonia reduced the tolerance of hybrid grouper to ammonia-N. Furthermore, ammonia-N exposure caused an increase in oxygen consumption in hybrid grouper. After ammonia-N exposure for 96h, 10 amino acids contents and activities of AST and ALT elevated in hybrid grouper muscle. The study revealed that combined exposure to hypoxia and ammonia-N significantly increased glucose metabolism, oxygen consumption and amino acid metabolism in hybrid grouper, and presented significant synergistic effects.

Impacts of dietary phosphorus level on growth, antioxidant capacity and immunity in juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) fed with high-lipid diets

The study was designed to evaluate the effect of available phosphorus on growth performance, antioxidant capacity and non-specific immunity in hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus) fed with high-lipid diets. Juvenile fish (8.06 ± 0.02 g) were subjected to six different dietary treatments over a period of eight weeks. These treatments consisted of diets (16% lipid level and 45% protein level) containing 0.3%, 0.58%, 0.67%, 0.76%, 0.85% and 0.94% available phosphorus (MCP), designated P1 (control), P2, P3, P4, P5 and P6, respectively. The results showed that (1) P1 group had suppressed final weight, weight gain and specific growth rate, while the other phosphorus experimental groups had significantly higher growth performance than the P1 group (P < 0.05). (2) With increasing phosphorus level, serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) enzyme activities increased significantly (P < 0.05). (3) With the increase in dietary phosphorus level, the reactive oxygen species (ROS) content in the liver was significantly decreased (P < 0.05). And the malondialdehyde (MDA) content was significantly decreased, while SOD, CAT, lysozyme (LYS), alkaline phosphatase (AKP), aspartate transaminase (AST) enzyme activities, T-AOC and IgM contents were significantly increased (P < 0.05) (4 The expression of antioxidant genes, such as hsp70, hsp90, sod, cat, gpx, were significantly higher in the appropriate phosphorus level groups than P1 group (P < 0.05), meanwhile the expression of proinflammatory factors, such as il6, il8, tnfα, was significantly reduced (P < 0.05). (6) In the attack experiment, the survival rate of P4 group was the highest, and the survival rate of P2 and P1 groups were the lowest. In conclusion, the appropriate addition of phosphorus can improve growth, antioxidant capacity of fish and disease resistance, and we recommend its addition at 0.67% to 0.77% in diet.

Corn gluten meal diets supplemented with dietary L-carnitine for juvenile hybrid grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatus): Impacts on growth performance, immune response and flesh quality

The focus of this research was to assess if corn gluten meal diet supplemented with L-carinitine (LC) LC0, LC0.2, LC0.4, LC0.6, LC1.2, LC1.4, LC1.6, with LC levels of 0 for the control group, 200, 400, 600, 1200, 1400, and 1600 mg/kg, respectively, may be a viable option for juvenile hybrid grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatus). It’s impact on juvenile hybrid grouper growth, immunity, gene expression, and disease resistance. Each group in the experiment had three replicates (initial weight = 13.57 ± 0.00 g) and were fed their respective diets for eight weeks. When LC0.2 was compared to LC0, it showed a significant improvement on growth (P < 0.05). The treatment groups had no differences in crude protein, moisture, or ash content. Serum acid phosphatase, alkaline phosphatase, total antioxidant capacity, and glutathione peroxidase all increased. Fish fed LC0.2 had more steatosis in their hepatocytes in the liver than fish fed LC0, however the differences were not significant in LC0 (P ˃ 0.05). In the LC0.6, LC1.2, and LC1.4 groups, FAS mRNA levels were significantly downregulated. The expression of PPARA and PPARR was higher in the LC0.2 and LC0.4 groups, but not significantly different (P ˃ 0.05) from the LC0. In comparison to LC0, the fish fed diets LC0.2 and LC0.6 had the lowest mortality rate (P < 0.05) in a bacterium challenge test. Finally, based on all of the factors, replacing FM with CGM supplemented with LC0.2 (200 mg/kg) might be used to meet the nutritional needs of fish.