Journal of fish diseases最新文献

{"title":"Development of a Colourimetric Loop-Mediated Isothermal Amplification Assay for Rapid Detection of Streptococcus dysgalactiae","authors":"Tien-Tien Vicky Lau,&nbsp;Suat-Moi Puah,&nbsp;Kek-Heng Chua","doi":"10.1111/jfd.70202","DOIUrl":"10.1111/jfd.70202","url":null,"abstract":"<div>\u0000 \u0000 <p><i>Streptococcus dysgalactiae</i> is an emerging fish pathogen that causes streptococcosis, resulting in significant economic losses in aquaculture. Conventional detection methods, such as polymerase chain reaction assays, rely on sophisticated, expensive instrumentation, which limits their applicability in resource-limited or field settings. In this study, we developed a rapid, user-friendly and closed-tube colourimetric loop-mediated isothermal amplification (LAMP) assay for the detection of <i>S. dysgalactiae</i>. Six primers targeting the <i>sagB</i> gene were designed and assay conditions were optimised to enable visual detection. The LAMP assay produced results within 50 min and detected target bacteria at concentrations as low as 500 pg (1.195 × 10⁸ copies/reaction), with high specificity and no cross-reactivity observed against eight non-target bacterial species. Overall, this LAMP assay operates under isothermal conditions and provides clear visual readouts, offering a foundation for future field-based testing in aquaculture settings using fish and water samples.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 10","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First Record of Morphological Abnormalities in an Embryo of the Longtail Stingray (Hypanus longus) From the Ecuadorian Pacific","authors":"Christopher Mera,&nbsp;Nicole Suárez-Aguilar,&nbsp;Diego Mejía,&nbsp;Jesús Briones-Mendoza,&nbsp;Maribel Carrera-Fernández","doi":"10.1111/jfd.70208","DOIUrl":"10.1111/jfd.70208","url":null,"abstract":"<div>\u0000 \u0000 <p>This short communication reports the first record of multiple morphological anomalies in an embryo of <i>Hypanus longus</i> from Ecuadorian waters. A gravid female <i>H. longus</i> contained two embryos in the uterus: one exhibiting normal morphology and the other presenting several severe anomalies, including an opening in the chondrocranial membrane, separation of the pectoral fins and an incomplete pelvic fin. In addition, a helical torsion of the caudal fin was observed, an anomaly not previously reported in batoids. The deformities observed would likely have severely impaired the embryo's growth and development, drastically reducing its chances of survival.</p>\u0000 </div>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":"49 10","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147856504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature Influences Pseudocapillaria tomentosa Infections in Zebrafish, Danio rerio (Hamilton 1822).","authors":"Connor Leong, Ruby Scanlon, Corbin J Schuster, Michael L Kent, Thomas J Sharpton","doi":"10.1111/jfd.70268","DOIUrl":"https://doi.org/10.1111/jfd.70268","url":null,"abstract":"<p><p>Poikilothermic organisms like fish are key economic drivers in aquaculture and the ornamental fish trade. Climate change impacts the health of fish because poikilothermic hosts experience the same temperature as their environment, making temperature a critical determinant of parasite infection dynamics. Pseudocapillaria tomentosa, a capillarid nematode infecting approximately 20% of zebrafish research facilities, provides an excellent model for investigating temperature effects on nematode development because zebrafish can tolerate a wide temperature range. We examined how water temperature influences egg development and worm maturation across the zebrafish's tolerable thermal range (13°C-35°C). Eggs held at 4°C or 13°C failed to larvate but resumed development when returned to 28°C. Larvation increased at 35°C, though infectivity was reduced in larval zebrafish. In adult zebrafish, cold water (13°C) slowed worm development for up to 3 months; only immature larvae were observed even at 102 days post-exposure. Returning these fish to 28°C triggered rapid maturation, with gravid females appearing within 1 month. Conversely, fish held at 35°C had reduced worm burdens and arrested maturation compared to 28°C controls, with development resuming after temperature reduction. These findings align with field observations of seasonal P. tomentosa dynamics in temperate climates.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70268"},"PeriodicalIF":2.3,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148864961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ulvan Polysaccharide Enhances the Efficacy of an Injectable Yersinia ruckeri Vaccine in Rainbow Trout (Oncorhynchus mykiss).","authors":"Mohammad Mazandarani, Majid Khanzadeh, Mohammad Sudagar, Hamed Paknejad, Ali Taheri Mirghaed, Ali Kavousi","doi":"10.1111/jfd.70281","DOIUrl":"https://doi.org/10.1111/jfd.70281","url":null,"abstract":"<p><p>This research was designed to explore the immunogenicity of the yersiniosis vaccine and the effect of Ulvan as a natural adjuvant on immune, antioxidant and survival parameters in Oncorhynchus mykiss. A total of 450 O. mykiss (mean body weight 52.90 ± 2.02 g) were allocated to three experimental treatments, each with three replicate tanks. Treatments were: (1) injectable inactivated Yersinia ruckeri vaccine (Vac), (2) the same vaccine formulated with Ulvan as an adjuvant (Vac + U) and (3) an unvaccinated control group (Ctrl) receiving phosphate-buffered saline (PBS). White blood cells were significantly elevated in all vaccine-treated groups compared with the Ctrl group on days 30 and 60 (p < 0.0001). In contrast, no significant treatment effects were observed for red blood cells (p = 0.1078), haemoglobin (p = 0.2646), or haematocrit (p = 0.2352) at either sampling time. There were no significant treatment impacts on total protein (p = 0.3330) or serum globulin (p = 0.6521) at the 30- or 60-day samplings. Conversely, serum albumin was notably elevated in the Vac + U group relative to the Ctrl at both 30 and 60 days (p = 0.0244). Vaccination induced pronounced increases in both serum immune (lysozyme, total immunoglobulin, NBT) and antioxidant (catalase, superoxide dismutase, glutathione peroxidase) parameters at 30 and 60 days post-immunization compared with Ctrls (p < 0.05). Antibody titers against yersiniosis were significantly higher in all vaccine-treated groups than in the Ctrl group at 30 and 60 days post-immunization (p < 0.0001). Survival rate after a two-week Y. ruckeri challenge was 73.33% (Vac), 86.66% (Vac + U) and 16.66% (Ctrl); survival in the vaccine-treated groups was notably higher than in the Ctrl group (p < 0.0001). The results indicated that both the vaccine and the Vac + U formulation enhanced biochemical markers, immune-antioxidant responses, serum antibody titers and survival following challenge with Y. ruckeri infection. Among the tested groups, the Vac + U demonstrated the greatest effectiveness, likely due to the presence of Ulvan as an adjuvant.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70281"},"PeriodicalIF":2.3,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148864870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of Salinity Tolerance in Lepeophtheirus salmonis Following Five Generations of Freshwater Treatment Selection.","authors":"Reza Ghanei-Motlagh, Shona K Whyte, Manuel Soto-Dávila, Eyesun Fajei, Maricruz Guevara, Amber F Garber, Gro Vee, Preben R Antonsen, Gordon Ritchie, Mark D Fast","doi":"10.1111/jfd.70282","DOIUrl":"https://doi.org/10.1111/jfd.70282","url":null,"abstract":"<p><p>Non-medicinal approaches for controlling sea lice (Lepeophtheirus salmonis) infestations, such as freshwater (FW) treatments, have been increasingly implemented to support more sustainable parasite control in aquaculture. This study evaluated the efficacy of FW treatment against sea lice under controlled experimental conditions and assessed the potential development of resistance across multiple generations. Sea lice populations were maintained over five consecutive generations, and FW efficacy was evaluated by quantifying lice abundance on Atlantic salmon before and after treatment. Resistance assessment involved comparative bioassays using copepodid and adult life stages from two distinct populations, one exposed to FW and the other a saltwater (SW) control group. Our results demonstrated that a 4 h FW treatment significantly reduced total lice abundance, while an extended 18-day exposure resulted in complete detachment of all lice from salmon. Importantly, bioassay comparisons revealed no evidence of resistance development, as both FW-exposed and SW-control populations maintained similar susceptibility across generations. The absence of measurable changes in salinity tolerance over multiple generations suggests that FW protocols may remain a viable and sustainable management strategy. However, the potential for genetic or epigenetic variation in FW tolerance among lice populations warrants further investigation to better understand long-term implications for treatment efficacy.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70282"},"PeriodicalIF":2.3,"publicationDate":"2026-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148850717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Aptamer-Based Rapid Detection Kit Against Streptococcus agalactiae in Juvenile and Adult Red Hybrid Tilapia Under Control Condition.","authors":"Muhamad Faizal Mohd, Nur Nazifah Mansor, Mohd Firdaus Nawi, Azmeer Azzar Abdul Hamid, Mohd Hamzah Mohd Nasir, Mohd Syafiq Mohammad Ridzuan, Azila Abdullah, Siti Zahrah Abdullah","doi":"10.1111/jfd.70279","DOIUrl":"https://doi.org/10.1111/jfd.70279","url":null,"abstract":"<p><p>Streptococcus agalactiae is one of the most important bacterial pathogens causing streptococcosis in tilapia aquaculture, resulting in substantial economic losses worldwide. Rapid on-site diagnosis is essential for timely disease intervention; however, available laboratory-based methods are time-consuming and require specialised equipment. This study evaluated an aptamer-based lateral flow assay (LFA) for the rapid detection of S. agalactiae in the body mucus of experimentally infected red hybrid tilapia (Oreochromis spp.). Fish weighing 50 and 150 g were intraperitoneally challenged with an LD₅₀ dose (approximately 1 × 10⁷ CFU/mL) of S. agalactiae. Mucus samples were collected at 2, 4, 8, 12, 16, 20 and 24 h post-infection and analysed using the LFA, with PCR serving as the reference method. The assay detected S. agalactiae as early as 4 h post-infection in both size groups, while statistically reliable detection was achieved from 8 h onwards. Diagnostic sensitivity increased from 10% to 100% in 50 g fish and from 30% to 100% in 150 g fish between 4 and 16 h post-infection. No cross-reactivity was observed with Streptococcus iniae or Aeromonas hydrophila, indicating promising analytical specificity within this limited evaluation panel. The assay produced visual results within 15 min and exhibited a detection limit of 6.25 μg/mL total mucus protein, whereas PCR detected down to 3.125 μg/mL. No significant difference in diagnostic performance was observed between fish size groups. These findings demonstrated that the aptamer-based LFA establishes a strong proof-of-concept for the early detection of S. agalactiae infection using non-invasive mucus samples under controlled laboratory conditions. While the assay shows significant potential as a practical diagnostic tool, further field validation is required to fully support routine disease surveillance and management in tilapia aquaculture.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70279"},"PeriodicalIF":2.3,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148818593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discovery of Signature Metabolites as Potential Biomarkers for Anguillid Herpesvirus 1 (AngHV-1) During Outbreak in Anguilla bicolor Glass Eel.","authors":"Ekky Ilham Romadhona, Sutanti Sutanti, Handang Widantara, Yohanes Pamungkas Bawono, Annisa Fitri Larassagita, Betutu Senggagau, Edy Barkat Kholidin, Lili Sholichah, Indah Mastuti, Bunga Rante Tampangallo, Arief Taslihan, Sri Nuryati","doi":"10.1111/jfd.70276","DOIUrl":"https://doi.org/10.1111/jfd.70276","url":null,"abstract":"<p><p>This study evaluated the metabolites of Anguilla bicolor during an outbreak of Anguilid Herpevirus 1 (AngHV-1) disease. Two experimental groups, infected glass eels (P) and healthy glass eels (N), were established, with three biological replicates per group, each replicate comprising pooled samples from 10 glass eels (0.15 ± 0.03 g). Metabolomic analysis identified 212 compounds in the glass eel, including L-palmitin, PC (18:1/0:0), choline, cinnamic acid, PC (16:1/0:0), creatine, monoolein, hypoxanthine, L-histidine, oleostearic, L-carnitine, linoleoyl, urocanic acid, arachidonic acid and taurocholic acid, which exhibited the 15 highest VIP scores. The infection with AngHV-1 affected key pathways, including histidine metabolism, beta-alanine metabolism, arginine biosynthesis and nicotinate and nicotinamide metabolism. Biomarker analysis revealed the downregulation of L-phenylalanine, Stearidonic acid, 2-Arachidonoyl glycerol, Acetyl-L-carnitine, carotenal and γ-Guanidiobutyrate (p < 0.01). These findings suggest that six signature metabolites are potential biomarkers associated with AngHV-1 infection in A. bicolor glass eels.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70276"},"PeriodicalIF":2.3,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148808729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mortality in Salmon (Salmo salar) Fry Related to Lipoid Liver Disease Induced by Unbalanced Fatty Acid Composition of the Diet.","authors":"Caroline Ek, Lo Persson, Charlotte Axén","doi":"10.1111/jfd.70253","DOIUrl":"https://doi.org/10.1111/jfd.70253","url":null,"abstract":"<p><p>In 2023, all but one Swedish restocking farm rearing Baltic salmon and sea trout fry experienced massive mortality caused by lipoid liver disease (LLD). The struck farms used the same feed, and this was suspected to be the cause of the outbreak. We performed two parallel feed trials in three salmon populations as well as fatty acid and antioxidant analyses of feed and fish to investigate the causal relationship between the feed and the LLD mortality. Significant mortality was induced in one population and LLD histopathology was induced in all three populations in groups fed the suspected feed (test feed) but not in the control groups, linking the test feed to the outbreak in 2023. Fatty acid analysis revealed a difference in bound fatty acid composition between the suspected feed and the control feeds, including higher amounts of erucic acid. Erucic acid has negative health effects for fish by altering lipid metabolism. It is present in for example, capelin, a main ingredient in this feed. The test feed also contained lower levels of several antioxidants, especially vitamin A. Antioxidative status of the fish could not be fully analysed but results indicated a difference in antioxidative status between the populations.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70253"},"PeriodicalIF":2.3,"publicationDate":"2026-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148760275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Surveillance and Depopulation Strategies on Fish Disease Transmission Among Net-Cage Farms Near the Tongyeong Coast Based on a Spatiotemporal Hybrid Approach.","authors":"Gyoungsik Kang, Ju-Sung Kim, Kyung-Ho Kim, HyeongJin Roh","doi":"10.1111/jfd.70272","DOIUrl":"https://doi.org/10.1111/jfd.70272","url":null,"abstract":"<p><p>Infectious diseases among fish farms present significant challenges to fish health and production. Horizontal transmission serves as one of the main mechanisms driving outbreaks in these settings. The dynamics of horizontal transmission are influenced by pathogen properties, host characteristics and environmental factors. Additionally, the implementation of epidemiological interventions can further shape the patterns and consequences of infectious disease spread. However, there is a paucity of studies assessing how specific epidemiological measures, such as timely disease surveillance and strategic depopulation, influence transmission and outbreak outcomes. This study utilized a spatiotemporal hybrid model to assess pathogen dissemination following an infectious disease event in Tongyeong, a prominent area for floating net cage aquaculture in Korea. We investigated how variations in sampling intensity affected the timing of disease detection and analysed the impact of two control strategies (immediate culling upon detection versus no culling) on the progression of disease and fish mortality. Findings revealed significant differences in disease detection timing and probability based on the surveillance sampling size. Early detection of disease was achieved when 100 fish were sampled, as opposed to a delayed response when only 5 fish were tested. Furthermore, the conditions under which surveillance occurred had a notable impact on both the spatial spread and the success of depopulation measures. Generally, prompt detection followed by immediate depopulation led to a decrease in disease-related mortality over a wider area. However, this method also necessitated culling a substantially greater number of fish. Although the impact of these interventions may be influenced by geographical and environmental variables, our results suggest that the utility of depopulation strategies is closely linked to the efficacy of surveillance efforts and the epidemiological profile of the infection, such as its associated mortality rate and transmissibility.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70272"},"PeriodicalIF":2.3,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148764805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Targeting Peroxiredoxin 6: Tannic Acid Inhibits Singapore Grouper Iridovirus Infection via PRDX6-Dependent Pathway and Antioxidant Response.","authors":"Xiangmou Qin, Chen-Ao Li, Lin Huang, Qing Yu, Mingming Zhao, Yanxia Gao, Jiaxi Li, Jia Cai, Huapu Chen, Fei Ling, Junxiang Lai, Ermeng Yu, Mingzhu Liu, Pengfei Li","doi":"10.1111/jfd.70273","DOIUrl":"10.1111/jfd.70273","url":null,"abstract":"<p><p>Singapore grouper iridovirus (SGIV) is a major viral pathogen threatening grouper aquaculture. The lack of specific antiviral drugs underscores the urgent need to develop safe and effective control strategies. This study demonstrates that tannic acid (TA) exhibits significant anti-SGIV activity in vitro. In grouper spleen (GS) cells, TA inhibited SGIV replication in a concentration-dependent manner. Time-of-addition assays confirmed its antiviral efficacy when applied either before or after SGIV infection. Mechanistically, TA directly interfered with SGIV particle infectivity, viral adsorption, entry and intracellular replication. Network pharmacology analysis suggested TA's targets are associated with host cellular antioxidant pathways, among which Peroxiredoxin 6 (PRDX6) was identified as a potential target of TA. Further experiments confirmed that TA upregulated the Nrf2 antioxidant pathway and suppressed the expression of pro-inflammatory cytokines (IL-1β, IL-8). Notably, TA enhanced the expression of PRDX6, and overexpression of PRDX6 significantly inhibited SGIV replication, indicating that PRDX6 contributes to the antiviral effect of TA. In vivo, TA treatment not only restored PRDX6 expression in infected groupers but also significantly reduced viral load in liver and spleen following SGIV infection. These findings demonstrate that TA inhibits SGIV through direct viral interference and PRDX6-mediated antioxidant modulation, highlighting its potential as a natural therapeutic agent against SGIV.</p>","PeriodicalId":15849,"journal":{"name":"Journal of fish diseases","volume":" ","pages":"e70273"},"PeriodicalIF":2.3,"publicationDate":"2026-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148725039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}