Lates Calcarifer Research Articles

Ultrasonication on Collagen Yield, Physiochemical and Structural Properties from Seabass (Lates Calcarifer) Scales as Affected by Pretreatment and Extraction Conditions

This research explored the use of ultrasound as a pretreatment and extraction assisted process for extraction of collagen from seabass scales. Both acid-soluble (AC) and pepsin-soluble collagens (PC) were extracted with ultrasonication at different extraction times (24 and 48 h). Ultrasound pretreatment (PU) and ultrasound-assisted extraction (UE) notably improved AC extraction yields over 48 hours, registering 2.12% and 4.62%, respectively. The highest yield for PC, 21.85%, was achieved with 48 hours of ultrasound assisted extraction. Protein analysis verified the extracted collagens as type I, indicated by the presence of specific α and β chains. Further, FTIR spectra confirmed collagen's presence in all samples through distinct amide band peaks. Interestingly, ultrasound processes marginally reduced AC's thermal stability while boosting PC's thermal stability, especially when combined with pepsin treatment. Moreover, CD spectroscopy showed the preserved native structure of collagen across all samples. The ultrasound method increased collagen extraction yields and retained its structural integrity. These outcomes are pivotal for advancing collagen extraction methods in the biomedical and food sectors. Keywords: Seabass scales, Collagen, Ultrasonication, Molecular characterization, Physicochemical properties

Non‐Invasive Prediction of Barramundi (Lates calcarifer) Flesh Lightness Using Near‐Infrared Spectroscopy

Barramundi (Lates calcarifer) is an important aquaculture species extensively farmed throughout its natural distribution of Australia and Southeast Asia, as well as being increasingly farmed in the Middle East, USA, and Europe. Barramundi has a firm, pink‐white flesh; however, fillets from farmed barramundi often exhibit grey colouration. This grey colouration detracts from its market appeal, leading to challenges in consumer acceptance and competitiveness of the product against other white fillet fish. Selective breeding, environmental manipulation, and dietary adjustments are being investigated to reduce grey flesh colouration. Yet, the absence of a rapid, noninvasive approach to predict greyness in flesh means that large numbers of samples cannot be quickly evaluated, and issues cannot be mitigated preharvest and noninvasively to preserve the fish. To address this issue, rapid analysis of flesh greyness was developed using noninvasive near‐infrared (NIR) spectroscopy through the fish skin. Thirty fish were purchased from a barramundi farm, filleted, and divided into 3 cm sections, yielding a total of 335 samples from both dorsal and ventral fillet regions. NIR spectral data were obtained from the skin side of all samples, and colouration data were collected from the flesh side of the same samples. Data were randomised into a training set (256 spectra) and a validation set (79 spectra). Predictive models were developed using flesh colour as the training input for skin NIR spectra. The refined partial least squares regression model explained 78% of the variation in the medial flesh colour (R2pe of 0.776, an RMSEP of 2.820, and an RPDpe of 2.122) demonstrating the ability to adequately predict the flesh quality through skin spectra. This highlights the potential of NIR spectroscopy as a dependable, noninvasive tool, enabling the rapid evaluation of large samples and offering the potential to address flesh colouration issues in barramundi preharvest.

Pathogenicity associated with an infestation of the marine leech parasite Pterobdella arugamensis in farmed fish.

The marine leech Pterobdella arugamensis is a hematophagous parasite, and the extent of injury to the host largely depends on the number of attached leeches. This study aimed to assess the pathogenicity of marine leeches in Asian seabass (Lates calcarifer) and tiger grouper (Epinephelus fuscoguttatus) fingerlings under laboratory conditions. Five groups of healthy Asian seabass and tiger grouper were exposed to varying numbers of marine leeches (0, 1, 10, 30, or 70 per fish) for 7 d. Infested Asian seabass and tiger grouper both showed pathological changes even with only 1 leech, manifesting as clinical signs like haemorrhages. The cumulative mortality at 7 d post-exposure (dpe) was 11 or 33% for Asian seabass infested with 1 or 10 marine leeches, respectively. Fish with 30 or 70 marine leeches showed higher rates of mortality (56%). A similar trend was seen in tiger grouper, with mortality rates reaching 78% in fish with 30 or 70 marine leeches, and 56 or 33% in fish with 10 leeches or 1 leech, respectively. Factorial analysis of mortality after 7 dpe between both species showed significant differences (2-way ANOVA p = 0.001) when exposed to varying numbers of marine leeches. The haematocrit values differed significantly between Asian seabass or tiger grouper infested with either 0 or 1 marine leech and those infested with 10, 30, or 70 marine leeches (1-way ANOVA, p = 0.0001). This suggests that marine leech infestation has a measurable impact on both species. Consequently, fish farmers should promptly address leech infestation upon discovery in their cages.

Effect of Dietary Seaweed (Gracilaria pulvinata and Sargassum ilicifolium) on Serum and Mucosal Immunity, Some Growth and Immune‐Related Genes Expression, Antioxidant Status, and Fatty Acid Profile in Asian Seabass (Lates calcarifer)

This study was done to appraise the effects of the combination of dietary Gracilaria pulvinata and Sargassum ilicifolium on growth, immunity, and fatty acid profile in Asian seabass (Lates calcarifer). A total of 540 juveniles (36.06 ± 0.05 g) were stocked into eighteen 200 L tanks and divided into six experimental treatments, each in triplicate. Fish were fed diets containing 0 (control), 3% (SW3), 6% (SW6), 9% (SW9), 12% (SW12), and 15% (SW15) mixtures of both seaweeds powder in equal proportions (1 : 1) for 56 days. There was no improvement in weight gain parameters. Serum lysozyme and peroxidase activities in SW9 and SW12 treatments were significantly higher in compare to other treatments. The highest activities of skin mucus lysozyme, alkaline phosphatase, and total protease were observed in the SW12. Liver igf-1, il-1β, il-8, and lysozyme expression showed a rising trend up to SW9 and then decreased. Liver antioxidant enzymes activity and glutathione content showed a similar pattern of changes. Liver total antioxidant capacity was highest in the SW9 treatment, while the lowest value of liver malondialdehyde was observed in the 12% seaweed treatment. The amount of total n‐3 polyunsaturated fatty acids, especially docosahexaenoic acid, was higher in the SW12 and SW15 treatments in compare to others. Our findings suggest that adding 9%–12% of Gracilaria and Sargassum seaweed powder to the diet improves serum and mucosal immunity, antioxidant status, and fatty acid profile in L. calcarifer juveniles.

Fish Diversity in Mangrove Conservation Area of Labuhan, Bangkalan, East Java – Indonesia, with Emphasis on Important Fishery Species

Mangroves are one of the most productive ecosystems which support biodiversity of aquatic invertebrate and vertebrates. Many local fishermen in Labuhan village, Sepulu, Bangkalan – East Java depends on the existence of mangrove for fisheries production, including economically important species. This study aimed to determine the diversity of fish within mangrove (the inner mangrove/IM) and coastal water in front of mangrove (the outer mangrove/OM). Samplings with several active and passive fishing gears (scoop net, gill net, fish trap) were conducted three times during high tide periods in June 2021, October 2021 and July 2022. The fish diversity analyzed with the Shannon-Wiener (H') diversity index while similarity of fish communities was approached using the Sorensen similarity index. A total of 36 fish species were identified, with 23 species recorded from IM and 22 species from OM. The IM always has higher species richness and abundance, that is 20.33±0.58 species and 125.33±26.27 individuals compared to the OM with 13.33±3.06 species and 36.67±13.01 individuals. The IM also has a relatively higher value of H’ (2.49±0.06) than OM (2.207±0.18). The value of Sorensen index was 0.419 with only 9 shared species in both areas. The most dominant species in the IM is Mozambique tilapia (Oreochromis mossambicus) while in OM there is Singapore glass perchlet (Ambassis kopsii). Sixteen species are considered having economic value; with most of high economic important species, e.g. Milkfish (Chanos chanos), Greenback mullet (Planiliza subviridis), Great barracuda (Sphyraena barracuda) and Barramundi (Lates calcarifer) were usually caught at juvenile and/or immature stages.

Replacement of Fish Meal with a Combination of Fermented Fish and Soybean Meal in the Diet of Juvenile Asian Seabass, Lates calcarifer (Bloch, 1790)

Replacement of Fish Meal with a Combination of Fermented Fish and Soybean Meal in the Diet of Juvenile Asian Seabass, Lates calcarifer (Bloch, 1790)

Development of Immersion and Oral Bivalent Nanovaccines for Streptococcosis and Columnaris Disease Prevention in Fry and Fingerling Asian Seabass (Lates calcarifer) Nursery Farms.

In the present study, chitosan-based bivalent nanovaccines of S. iniae and F. covae were administered by immersion vaccination at 30 and 40 days after hatching (DAH), and the third vaccination was orally administered by feeding at 50 DAH. ELISA revealed that the levels of total IgM and specific IgM to S. iniae and F. covae were significantly elevated in all vaccinated groups at 10, 20, and 30 days after vaccination (DAV). A qRT-PCR analysis of immune-related genes revealed significantly higher IgT expression in the vaccinated groups compared to the control group, as revealed by 44-100-fold changes in the vaccinated groups compared to the control (p < 0.001) at every tested time point after vaccination. All vaccinated groups expressed IgM, MHCIIα, and TCRα at significantly higher levels than the control group at 10 and/or 20 DAV (p < 0.05). In the S. iniae challenge tests, the survival of vaccinated groups ranged from 62.15 ± 2.11 to 75.70 ± 3.36%, which significantly differed from that of the control group (44.44 ± 1.92%). Similarly, all vaccinated groups showed higher survival rates of 68.89 ± 3.85 to 77.78 ± 5.09% during F. covae challenge than the control groups (50.00 ± 3.33%) (p < 0.05).

THE EFFECT OF ADDING PETROFISH PROBIOTICS TO FEED AT DIFFERENT DOSES ON THE GROWTH AND SURVIVAL OF BARRAMUNDI (Lates calcarifer) JUVENILES

This study aimed to determine the effect of adding Petrofish probiotics to feed at different doses on the growth and survival of barramundi (Lates calcarifer) juveniles. The research utilized an experimental method with 120 barramundi juveniles as test subjects, distributed into treatments A (Control), B 10mL/kg dosage), C (15mL/kg dosage), and D (20mL/kg dosage). The study was conducted for 30 days, using 12 buckets containing ten barramundi juveniles. The research employed a Completely Randomized Design (CRD) with Analysis of Variance (ANOVA), followed by Least Significant Difference (LSD) post hoc tests. The results indicated significant effects for each treatment. The highest absolute weight and length were observed in treatment D at 0.90 g and 0.73 cm, followed by treatment C at 0.77 g and 0.67 cm, treatment B at 0.69 g and 0.62 cm, and the lowest values were in treatment A at 9.51 g and 0.58 cm

Effects of varying protein and lipid levels, with or without the addition of L-carnitine supplementation on growth performance and nutrient utilization of Asian Seabass (Lates calcarifer) reared in recirculating aquaculture system

In a 60-day feeding trial, the impact of supplementing L-carnitine to low protein high energy (LPHE) diets was investigated. The study focused on the growth performance, nutrient utilization, health status, and fatty acid profile of Asian seabass (Lates calcarifer) reared in a recirculating aquaculture system (RAS). Seven iso-energetic (∼4600 Kcal/kg) diets with varying levels of protein and lipid, both with and without L-carnitine supplementation viz. control- (47/10), T1(44/12), T2(41/14), T3(44/12 with L- carnitine 0.05%), T4(44/12 with L- carnitine 0.1%), T5-(41/14 with L- carnitine 0.05%), T6 (41/14 with L- carnitine 0.1%) were prepared. L. calcarifer fingerlings with an average weight of 5.2 ± 0.1 g were randomly allocated to each treatment in triplicate, with 50 fingerlings per replicate. The fingerlings were fed three times a day until they reached satiation. The findings of present study revealed significant variations (P < 0.05) in final weight, weight gain, Specific Growth Rate (SGR), Feed Conversion Ratio (FCR), Protein Efficiency Ratio (PER), and Thermal Growth Coefficient (TGC) among different treatments, demonstrating linear trends. Fish survival rates across treatments showed no significant variations (P > 0.05) and lacked both linear and quadratic trends. Dietary treatments did not have an overall significant effect (P > 0.05) on whole-body moisture and crude protein contents of seabass, showing no discernible linear or quadratic trends. However, notable differences (P < 0.05) were observed in whole-body lipid and total ash contents, displaying linear and quadratic trends. The n-6 polyunsaturated fatty acid (PUFA) and n-3 PUFA content exhibited an overall significant impact due to dietary variations, showing both linear and quadratic trends. Cholesterol, triglyceride, and cortisol contents showed statistically significant overall differences, with discernible linear and quadratic trends across treatment groups. Superoxide dismutase (SOD) and catalase (CAT) activity also demonstrated an overall significant effect, accompanied by a linear trend. In conclusion, adding L-carnitine at a 0.1% concentration to diets containing 44% protein and 12% lipids boosted both growth performance and antioxidant response of L. calcarifer.

LC-MS-based lipidomics analyses of alterations in lipid profiles of Asian sea bass (Lates calcarifer) induced by plasma-activated water treatment

A lipidomics approach based on liquid chromatography-mass spectrometry was employed to investigate alterations in lipid profiles within the muscles of Asian sea bass (ASB) (Lates calcarifer) post-treatment with plasms-activated water (PAW). Lipidomics studies detected 1500 diverse lipid types in ASB muscles; the phosphatidylcholine (PC) lipid subclass constituted the highest number of lipids (21.07 %), followed by triglycerides (TGs, 20.53 %) and phosphatidylethanolamine (PE, 12.73 %). Comparative analysis between PAW-treated ASB and raw ASB revealed the presence of differentially abundant lipids, with 48 lipids accumulating at high levels and 92 at low levels. Pathway enrichment analysis identified a total of seven lipid-related metabolic pathways; glycerophospholipid metabolism emerged as the predominant pathway. Furthermore, the content of saturated fatty acids in PAW-treated ASB increased from 1059.81 μg/g (raw ASB) to 1099.77 μg/g. Conversely, the content of monounsaturated and polyunsaturated fatty acids decreased from 645.81 μg/g and 875.02 μg/g to 640.80 μg/g and 825.25 μg/g, respectively. Collectively, these results indicate significant alterations in ASB lipid profiles following PAW treatment, establishing a theoretical foundation for understanding the mechanism involved in promoting lipid oxidation.

Immersion prime and oral boost vaccination with an inactivated Vibrio harveyi vaccine confers a specific immune response and protection in Asian seabass (Lates calcarifer)

Asian seabass (Lates calcarifer) holds significant economic value in fish farming in the Asia-Pacific region. Vibriosis caused by Vibrio harveyi (Vh) is a severe infectious disease affecting intensive farming of this species, for which prevention strategies by vaccination have been developed. This study investigated an alternative approach to injectable vaccination to prevent vibriosis in Asian seabass juveniles. The strategy begins with an immersion prime vaccination with a heat-inactivated Vh vaccine, followed by two oral booster doses administered at 14- and 28-days post-vaccination (dpv). Expression of five immune genes TNFα, IL1β, CD4, CD8, and IgM in the head kidney and spleen, along with investigation of anti-Vh antibody response (IgM) in both systemic and mucosal systems, was conducted on a weekly basis. The efficacy of the vaccines was assessed by a laboratory challenge test at 43 dpv. The results showed that the immunized fish displayed higher levels of mRNA transcripts of the immune genes after the immersion prime and the first oral booster dose compared to the control group. The expression levels peaked at 14 and 28 dpv and then declined to baseline at 35 and 42 dpv. Serum specific IgM antibodies were detected as early as 7 dpv (the first time point investigated) and exhibited a steady increase, reaching the first peak at 21 dpv, and a second peak at 35 dpv. Although the antibody levels gradually declined over subsequent weeks, they remained significantly higher than the control group throughout the experiment. A similar antibody response pattern was also observed in the mucosal compartment. The laboratory challenge test demonstrated high protection by injection with 1.65 × 104 CFU/fish, with a relative percent of survival (RPS) of 72.22 ± 7.86 %. In conclusion, our findings highlight the potential of an immersion prime-oral booster vaccination strategy as a promising approach for preventing vibriosis in Asian seabass.

Optimization of cold plasma combined treatment process and its effect on the quality of Asian sea bass (Lates calcarifer) during refrigerated storage.

Cold plasma exhibits broad applicability in the realm of fish sterilization and preservation. The combination process of plasma-activated water and dielectric barrier discharge (PAW-DBD) was optimized, and its disinfection effects on bass fillets were studied. The best conditions for disinfection of PAW-DBD were as follows. Bass fillets were soaked in PAW for 150 s, and then treated by DBD system at 160 kV for 180 s. The total viable count (TVC) reduced by 1.68 log CFU g-1 . On the 15th day of refrigerated storage, TVC of PAW-DBD group was 7.01 log CFU g-1 , while the PAW and DBD group exhibited a TVC of 7.02 and 7.01 log CFU g-1 on day 12; the TVC of the control group was 7.13 log CFU g-1 on day 6. The sensory score, water-holding capacity, and 2-thiobarbituric acid reactive substance values of the PAW-DBD group were significantly higher than those of PAW and DBD group (P < 0.05), whereas the TVC, Pseudomonas spp. count, and pH of the group were significantly lower (P < 0.05) during refrigerated storage. PAW-DBD treatment can enhance the disinfection effect, maintain good quality, and extend the storage period of bass fillets. © 2023 Society of Chemical Industry.

Efficacy of whole-cell-based monovalent and bivalent vaccines against Streptococcus iniae and Flavobacterium covae in fingerling Asian seabass (Lates calcarifer)

Streptococcosis and columnaris caused by Streptococcus spp. and Flavobacterium spp. have been recognized as critical problems in Asian seabass aquaculture development because they cause severe mortality. In this study, we identified various isolates of S. iniae and F. covae from diseased Asian seabass farmed in Thailand for use as candidates for vaccine development. The efficacy of the vaccines was evaluated by challenge tests and immune parameter analyses in fish that received whole-cell-based monovalent and bivalent vaccines containing S. iniae (Sin) and F. covae (Fco) delivered by top-dressed feed (TD) and intraperitoneal injection (IP). The results showed that all vaccinated groups exhibited increased antibody titers compared with control fish that peaked on day 28 after booster administration with high detection levels in the Sin-IP and Fco-IP groups. Moreover, the immune responses to the injected monovalent vaccines (Sin-IP and Fco-IP) were better than the responses in the other vaccinated groups. The hematological and innate immunological parameters were significantly increased by Sin-IP and Fco-IP, particularly lysozyme activity, nitroblue tetrazolium (NBT) activity, bactericidal activity, and white blood cell numbers, and immune-related genes, including IgM, MHC-IIα, TCRß and CD4, were significantly upregulated in the head kidney, whole blood and spleen (P < 0.05). After experimental challenge, survival in the Sin-IP and Fco-IP groups was significantly higher than that in the Sin-TD, Fco-TD, Sin + Fco-TD, and Sin + Fco-IP groups, with 80.0 % and 60.0 % survival after S. iniae and F. covae infection, respectively. In contrast, survival after bacterial challenge in the control groups was 10 % in each group. Histopathological analysis revealed that Sin-IP- and Fco-IP-vaccinated fish exhibited significantly more goblet cells in the intestines and melanomacrophage centers (MMCs) in the head kidney and spleen than those in the other groups (P < 0.05). Overall, the results of our study indicated that the monovalent vaccines Sin-IP and Fco-IP provoked better vaccine efficacy and immune responses than their orally administered counterparts, and these results are consistent with those from the immunological assays that showed significantly increased responses after immunization.

Lc-ms-based lipidomics analyses revealed changes in lipid profiles in Asian sea bass (Lates calcarifer) with dielectric barrier discharge (DBD) atmospheric plasma treatment

A comprehensive LC-MS-based lipidomics analysis of Asian sea bass (Lates calcarifer) muscle after dielectric barrier discharge (DBD) atmospheric plasma treatment was performed. Through the analysis, 1500 lipid species were detected, phosphatidylcholine (PC, 27.80%) was the most abundant lipid, followed by triglyceride (TG, 20.50%) and phosphatidylethanolamine (PE, 17.10%). Among them, 125 lipid species were detected and identified as differentially abundant lipids in Asian sea bass (ASB). PCA and OPLS-DA showed that ASB lipids changed significantly after DBD treatment. Moreover, glycerophospholipid metabolism was key metabolic pathways, as PC, PE, and lysophosphatidylcholine (LPC) were key lipid metabolites. The findings concerning fatty acids revealed that the saturated fatty acids (SFA) content of ASB after DBD treatment increased by 8.54%, while the content of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decreased by 13.77% and 9.16%, respectively. Our study establishes a foundation for the lipid oxidation mechanism of ASB following DBD treatment.

Hydrodynamic characteristics of an Asian sea bass-inspired underwater body

A novel underwater body geometry inspired from the morphology of Asian sea bass (Lates calcarifer) fish is developed, and its hydrodynamic coefficients for different combinations of angle of attack and drift angle are investigated using RANS-based CFD methods. The six degrees of freedom manoeuvring performance is evaluated by the calculation of surge, sway and heave forces and roll, pitch and yaw moments at Reynolds number 3.7 × 106. The numerical model is validated using experimental results for DARPA SUBOFF model. The sea bass sectional geometry has an inherent asymmetry about the horizontal plane, and this is observed in the force and moment coefficients. A detailed study for pressure coefficient and skin friction coefficient is presented, both along the length and circumferentially at specified locations for varying angles of attack and drift angles (-15° to 15°). Due to transverse pressure gradient, cross-flow structures are observed resulting in vortices from the mid-body that grow downstream, the strength depending on the angle of manoeuvre. It is observed that the sea bass-inspired body generates greater roll and pitch moments and heave force as compared to a symmetric tuna-inspired body for drift angles greater than 10°. The differences show the influence of asymmetry in underwater vessel geometry on its stability and performance during horizontal and vertical plane manoeuvres. The study of the hydrodynamic characteristics will aid the design of control surfaces and development of estimation of manoeuvring and propulsion performance for fish-inspired autonomous underwater vessels.

Monsoonal wet season influences the migration tendency of a catadromous fish (barramundi Lates calcarifer).

Many animals exhibit partial migration, which occurs when populations contain coexisting contingents of migratory and resident individuals. This individual-level variation in migration behaviour may drive differences in growth, age at maturity and survival. Therefore, partial migration is widely considered to play a key role in shaping population demography. Otolith chemistry and microstructural analysis were used to identify the environmental- and individual-specific factors that influence migratory behaviour in the facultatively catadromous barramundi (Lates calcarifer) at two distinct life history stages: firstly, as juveniles migrating upstream into fresh water; and secondly, as adults or sub-adults returning to the estuarine/marine spawning habitat. Monsoonal climate played an important role in determining the migration propensity of juveniles: individuals born in the driest year examined (weak monsoon) were more than twice as likely to undergo migration to freshwater than those born in the wettest (strong monsoon) year. In contrast, the ontogenetic timing of return migrations to the estuary by adults and sub-adults was highly variable and not strongly associated with the environmental parameters examined. We propose that scarce resources within saline natal habitats during lower rainfall years may provide an ecological incentive for juveniles to migrate upstream, whereas more abundant resources in higher rainfall years may promote resident life histories within estuaries. We conclude that inter-annual climatic variation, here evidenced by monsoonal strength, likely plays an important role in driving the persistence of diversified life histories within wild barramundi populations.

Insights into the functional properties of a natural free amino acid mix: Effect on growth performance, nutrient metabolism, and immune response in a carnivorous fish, Asian seabass (Lates calcarifer)

Dietary supplements containing a functional feed additive have been shown to be beneficial to fish and shellfish aquaculture. However, the functional properties of aquafeed formulations have rarely been reported in fish. This study aimed to investigate the effects of natural free amino acid mix (FAAM) supplementation as a functional solution on the growth performance and nutrient utilization in a carnivorous fish, Asian seabass (Lates calcarifer). Five isonitrogenous and isolipidic diets were prepared with graded supplementation levels of FAAM at 0 % (control group), 0.25 %, 0.50 %, 0.75 %, and 1.0 %, denoted as FAAM0, FAAM0.25, FAAM0.5, FAAM0.75, and FAAM1.0, respectively. The experimental fish were fed different dietary FAAM supplementations to apparent satiation twice daily for eight weeks. Significant improvements were observed in the growth performance of fish among the five groups (P < 0.05). Fish fed with FAAM0.75 displayed significantly increased activities of lysozyme, myeloperoxidase, catalase, and glutathione peroxidase (P < 0.05). The activities of digestive enzymes, including amylase, protease, and lipase, were enhanced by the supplementation of FAAM in the feed (P < 0.05), especially for the groups that contained more than 0.5 % FAAM in the feed. Furthermore, the morphological profile of the intestinal tract, including the mucosal fold height, width, thickness, and goblet cell, increased in fish fed with FAAM at 1.0 % (P < 0.05). Moreover, FAAM supplementation in diets not only modulated the expression of immune-related genes (glutathione peroxidase (GPx), complement (C)3, C4, and C-reactive protein) in the liver but also positively impacted the growth-ralated genes, including growth hormone (GH), GH receptor (GHR), insulin-like growth factor I (IGF-I), and IGF-II. In addition, the amounts of monounsaturated fatty acids (mainly oleic acid (C18:1n9c)) and polyunsaturated fatty acids-especially γ-linolenic acid (C18:3 n6) and α-linolenic acid (C18:3n3)-increased in fish fed with diets containing FAAMs (P < 0.05). Interestingly, the diets supplemented with FAAMs also had a positive effect on the economic indices in terms of revenue-to-cost ratios. These findings provide a scientific basis for the application of FAAMs as a functional solution that can be used in feed formulations for Asian seabass.

Effect of killed autogenous polyvalent vaccines against Vibrio harveyi, V. alginolyticus and Streptococcus iniae on survival and immunogenicity of Asian seabass (Latescalcarifer)

Vibriosis and Streptococcosis are the most important bacterial diseases that infect Asian seabass (Lates calcarifer) in various stages of its life cycle. Vaccination is a cost-effective strategy to prevent the occurrence of infectious diseases and increase sustainability in the aquaculture industry. This study was aimed to develop and evaluate a killed polyvalent vaccine against Vibrio harveyi, V. alginolyticus and Streptococcus iniae, delivered by intraperitoneal injection in Asian seabass. The fish were divided into three groups with 60 fish in triplicate: I) a control group injected with phosphate-buffered saline (PBS), II) a group vaccinated by polyvalent vaccine (V. alginolyticus + V. harveyi + S. iniae) and III) a group vaccinated with the same polyvalent vaccine plus an oral booster. Immunological parameters and antibody titer were measured before and at three, five-, and eight-weeks post-vaccination. The efficacy of the killed vaccine was assessed five weeks post-vaccination by challenging with each isolate separately. The vaccinated groups had higher survival rate than control group. The highest relative percentage survival rate, 85.71 ± 3.57 % was observed in group III when challenged with V. harveyi. The vaccinated fish produced significantly higher antibody titers against V. alginolyticus, V. harveyi and S. iniae than the control group (P < 0.05). Non-specific immune parameters were significantly enhanced in the vaccinated groups, especially group III, compared to the control. The results demonstrated that the administration of a killed polyvalent vaccine can effectively protect Asian seabass against V. alginolyticus, V. harveyi and S. iniae.

Susceptibility of Vibrio spp. from Gill of Barramundi (Lates calcarifer) Towards Antibiotics

Vibrio spp. bacteria are aquatic bacteria that can be found in brackish water and estuaries, and they have opportunistic pathogenic properties. These bacteria are usually dominant in brackish and estuarine areas such as river mouths, rivers, ponds, and seas with salinities between 20-40 ppt and a temperature of 37°C. The aim of this research is to determine the susceptibility and sensitivity of Vibrio spp. bacteria to various types of antibiotics. The Vibrio spp. bacteria isolated in this study were obtained from barramundi fish (Lates calcarifer). If they are still sensitive, the growth of Vibrio spp. bacteria can be inhibited by antibiotic administration. The effectiveness of antibiotics against Vibrio spp. bacteria in barramundi fish was tested using eight types of antibiotics, namely Co-Amoxiclav, Gentamicin, Doxycycline, Tetracycline, Azithromycin, Chloramphenicol, Ciprofloxacin, and Ampicillin. Bacteria that are sensitive to specific types of antibiotics have larger inhibition zones. The measurement of inhibition zones was carried out using a caliper by measuring the vertical and horizontal diameters and then dividing by 2 to obtain the average. This average was compared to a standard interpretative zone diameter chart to determine antibiotic sensitivity and resistance status using the Disk Diffusion method. Tetracycline and Ampicillin antibiotics can inhibit or are resistant to Vibrio spp. bacteria with a percentage of 0.08%. Gentamicin has greater sensitivity compared to the other tested antibiotics. In this study, the Vibrio spp. obtained are still sensitive to certain types of antibiotics and resistant to Ampicillin.

Antibiotic Resistance in Vibrio spp. Causing Disease in Barramundi Fish (Lates Calcarifer) Eye

The cultivation of barramundi fish (Lates calcarifer) is widely carried out because barramundi fish has a relatively high economic value. The disease in question is caused by Vibrio spp. bacteria, which are marine bacteria that often affect barramundi fish, and the treatment for the bacteria is antibiotics. Therefore, research was conducted to test several types of antibiotics and observe the bacterial resistance reaction to the administration of these antibiotics. The methods used in this study included media preparation, purification, and microscopic characterization, liquid media preparation, solid media preparation, and antibiotic sensitivity testing. Vibrio spp. are still sensitive to antibiotics at a rate of 61.27%, resistant at 18.14%, and intermediate at 20.59%. Bacterial isolate characteristics were divided into several types: Irregular, Punctiform, Round, and Round Umbonate. Irregular, Punctiform, Round, and Round Umbonate are still sensitive to antibiotics at rates ranging from 37.5% to 66.67%. Other results include intermediate and resistance with results ranging from 15.63% to 37.5% and 15.10% to 25.00%, respectively. The highest sensitivity results were found in antibiotics such as Gentamycin (98.94%), Co-Amoxiclave (86%), Tetracycline HCl (72.55%), Ciprofloxacin HCl (82.35%), Azithromycin (52.94%), and Doxycycline (54.90%). On the other hand, the highest intermediate and resistance results were found in chloramphenicol (52.94%) and Ampicillin (60.78%), respectively. Ampicillin is considered to be the antibiotic that the bacteria are resistant to because of its small inhibitory zone.