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Handfish (Family Brachionichthyidae) is the most threatened marine teleost fish family, however, there is little information on handfish health. We reviewed the results of submissions of mortalities from captive and captive bred spotted handfish (Branchionichthys hirsutus (Lacepède, 1804)) and red handfish (Thymichthys politus (Richardson, 1844)) from a public aquarium from January 2018 to February 2024. Seventeen cases for spotted handfish (comprising 33 individuals) and five cases for red handfish (one individual each) were submitted for mortality investigation. In 2018–2019, six of seven cases were diagnosed with scuticociliatosis. Other conditions included epitheliocystis (1 of 17), infections with metazoan parasites (2 of 17 for spotted handfish and 2 of 5 for red handfish) and hepatic lipidosis (4 of 17). Most submissions were fixed samples for histology with only one fish suitable for microbiology. We recommend development of a coordinated health program for all captive breeders and aquaria, which should include sampling protocols, collection, and preservation in a range of fixatives of all the dying or dead handfish and adapting sublethal sampling, including tank water to assess presence of pathogens and other microorganisms. Risk factors for handfish health in captivity should be assessed. Handfish health database should be established to avoid loss of corporate knowledge in this area. [ABSTRACT FROM AUTHOR]

Epitheliocystis, an intracellular bacterial infection in the gills and skin epithelium, has been frequently reported in Atlantic salmon (Salmo salar) during freshwater production in a number of countries. This study describes the prevalence and intensity of a natural epitheliocystis infection present in the gills of two strains of Atlantic salmon reared in either a flow‐through (FT) or a recirculation aquaculture system (RAS) in Ireland. Repeated sampling of gills prior to and throughout seawater transfer, histology and quantitative real‐time PCR were used to determine infection prevalence and intensity. Despite no clinical gill disease, and minor histopathological changes, epitheliocystis lesions were identified in histology at all time points. Specific PCR confirmed the presence of Candidatus Clavichlamydia salmonicola in both strains and its number of copies was correlated with intensity of epitheliocystis lesions. A significant interaction between hatchery system and fish strain on the prevalence and intensity of gill epitheliocystis was found both using histological and molecular methods. Specifically, fish from FT had higher prevalence and intensity than RAS reared fish and within FT, the Irish cohort were more affected than Icelandic. [ABSTRACT FROM AUTHOR]

Urinary calculi are observed in some cultured marine fish larvae and may negatively impact larval health and survival. This study assessed urinary calculi in striped trumpeter Latris lineata larvae from hatching to 28 days post‐hatching (dph). The prevalence of urinary calculi was variable over time and ranged from 15% to 50%, whereas the average size of calculi increased with larval age. Urinary calculi were semi‐translucent, light cream to white colour with irregular morphology and a uniform internal structure. The calculi resulted in pressure atrophy causing a distended epithelium of the urinary bladder of fish with calculi. The calculi were predominantly formed of calcium hydrogen phosphate (CaHPO4). Routine assessment of the prevalence of urinary calculi in marine fish larvae is recommended, along with other parameters, to monitor larval quality and inform hatchery management actions. [ABSTRACT FROM AUTHOR]

Epitheliocystis was present in the gills of all three fish species including armoured catfish, anabas and Nile tilapia from all four water bodies in central Vietnam. While armoured catfish has no economic value, anabas is a species target for artesian fishing and tilapia is one of two main fish species farmed in Vietnam. Keywords: anabas; armoured catfish; epitheliocystis; southeast Asia; tilapia; wild fish EN anabas armoured catfish epitheliocystis southeast Asia tilapia wild fish 755 760 6 04/08/22 20220501 NES 220501 Epitheliocystis is a condition affecting fish gill or skin epithelium and caused by intracellular Gram-negative bacteria including either Chlamydia or Proteobacteria (Blandford et al., 2018; Nowak & LaPatra, 2006; Polkinghorne et al., 2010; Stride et al., 2014). [Extracted from the article]

Amoebic gill disease (AGD) is a significant issue in Atlantic salmon mariculture. Research on the development of treatments or vaccines uses experimental challenges where salmon is exposed to amoebae concentrations ranging from 500 to 5,000/L. However, the water concentrations of N. perurans on affected salmon farms are much lower. The lowest concentration of N. perurans previously reported to cause AGD was 10/L. Here, we report that concentrations as low as 0.1/L of N. perurans can cause AGD. We propose that concentrations of N. perurans that reflect those measured on salmon farms should be used for future experimental challenges. [ABSTRACT FROM AUTHOR]

Skin lesions are commonly reported in farmed salmonids. Chinook salmon (Oncorhynchus tshawytscha), introduced from California USA, is the only salmonid species commercially farmed in New Zealand, although trout are cultured for release by Fish and Game New Zealand. There are several farming areas in New Zealand, including Marlborough Sounds, Canterbury and Stewart Island. While the industry has not been affected by any of the major production diseases seen internationally, skin lesions have been recorded with an increase in prevalence from 2012 onwards in the Marlborough Sounds and were associated with elevated summer mortalities on farms in 2015. Here we are proposing case definitions for different types of skin lesions for future monitoring and research. Based on our current understanding of the above skin conditions, we developed case definitions for spots, spreading spots, ulcerated spreading spots and Regular Outline Flank Ulcers defining a positive case for three study units, including individual fish, pen/unit and farm. [ABSTRACT FROM AUTHOR]

Amoebic gill disease (AGD) is a major challenge for the marine salmonid farming industry. This disease is caused by Paramoeba perurans, which is a parasitic amoeba that affects fish growth and survival. The present work aimed at improving Atlantic salmon (Salmo salar) diet formulation as a preventive treatment for AGD. Four diets with different quantitative composition of functional ingredients, such as arginine, premixes, plant extracts, nucleotides, beta glucans, and vitamins C and E were tested. In the first trial, fish fed the different diets were exposed to a 74‐day challenge trial with P. perurans, and their survival, feed intake, and growth performance were analyzed together with plasma properties and gill histopathology. Additionally, a second trial was performed where mucus constituents of Atlantic salmon fed the same diets were analyzed from fish that were not exposed to AGD. Results suggest a positive effect of the functional ingredients on Atlantic salmon survival and immune response. Particularly, the inclusion of arginine, microadditives, and vitamins C and E improved survival, with arginine being an important driver of pathogen protection. The protective role of mucus also improved with these functional ingredients in nonchallenged fish, as suggested by its greater viscosity and by the increased levels of lysozymes and polysaccharides. Overall, the present work supports improving diet formulation as a promising approach for the preventive treatment of AGD. [ABSTRACT FROM AUTHOR]

There are limited reports of infectious agents affecting Australian cowtail stingrays. In the present study, a new species of ascaridoid nematode belonging to the genus Mawsonascaris is described. The most distinct characteristic features were observed in females (the presence of a polar spine in the eggs and a flap‐like projection in the vulval area). An identification key for Mawsonascaris spp. is provided. Additionally, internal transcribed spacers (ITS) sequences were obtained for the new species. Alignment of the ITS sequence of the specimens in the present study with those deposited in GenBank showed that there exists no other highly similar sequence. Phylogenetic analyses resulted in a distinct grouping of our specimens supporting morphological distinction from previously described Mawsonascaris spp. Histology was used to investigate the pathology caused by the infection. Necrosis, inflammation and fibrosis were evident at the border of the nodules formed by parasite. A large number of parasites were present in muscularis mucosae and submucosa but not in the muscularis of the stomach. The parasites were associated with an increased inflammatory response, which was also found in the muscularis mucosae and submucosa. Similar pathology has been described in elasmobranchs infected by cestodes, although with more severe lesions. [ABSTRACT FROM AUTHOR]

Alongside this, except for review papers, the demise of the single-author scientific report, and the emergence of the hyper-authored papers (authorship list exceeding 100) are also noted. Can authorship credit be given to a writing tool that, unlike a human author, is unable to meaningfully take responsibility for the contents of a paper? Over the past decade across the majority of scientific disciplines, the number of authors listed per published manuscript has risen dramatically. [Extracted from the article]

Abstract: Freshwater bathing is one of the main treatment options available against amoebic gill disease (AGD) affecting multiple fish hosts in mariculture systems. Prevailing freshwater treatments are designed to be long enough to kill Neoparamoeba perurans, the ectoparasite causing AGD, which may select for freshwater tolerance. Here, we tested whether using shorter, sublethal freshwater treatment durations are a viable alternative to lethal ones for N. perurans (2–4 hr). Under in vitro conditions, gill‐isolated N. perurans attached to plastic substrate in sea water lifted off after ≥2 min in freshwater, but survival was not impacted until 60 min. In an in vivo experiment, AGD‐affected Atlantic salmon Salmo salar subjected daily to 30 min (sublethal to N. perurans) and 120 min (lethal to N. perurans) freshwater treatments for 6 days consistently reduced N. perurans cell numbers on gills (based on qPCR analysis) compared to daily 3 min freshwater or seawater treatments for 6 days. Our results suggest that targeting cell detachment rather than cell death with repeated freshwater treatments of shorter duration than typical baths could be used in AGD management. However, the consequences of modifying the intensity of freshwater treatment regimes on freshwater tolerance evolution in N. perurans populations require careful consideration. [ABSTRACT FROM AUTHOR]

Abstract: Finfish with asymptomatic Yersinia ruckeri infections pose a major risk as they can transmit the pathogen and cause clinical outbreaks in stock populations. Current tools have insufficient quantitative ability for accurately detecting the trace levels of Y. ruckeri typically associated with asymptomatic infection, necessitate invasive or lethal sampling, or require long processing times. This study presents a highly sensitive qPCR‐based method, targeting part of the Y. ruckeri 16S rRNA sequence, that is capable of detecting extremely low levels of Y. ruckeri in noninvasively collected faecal samples. Quantitative precision and accuracy of faecal sample analysis was consistent, despite the complexity of the faecal matrix. The assay demonstrated linearity over a six log‐wide dynamic range. Its limit of detection (LOD) and limit of quantification (LOQ) were 4 and 10 copies of the target sequence, respectively. Sensitivity of the assay was comparable to other qPCR‐based methods without requiring invasive or lethal sampling. Applicability as a screening strategy was tested using passively collected faecal samples. Asymptomatic Y. ruckeri infection was detected in all samples, although none of the fish exhibited overt infection. This method will be beneficial for finfish disease management if developed further as a noninvasive, screening tool against asymptomatic Y. ruckeri infection. [ABSTRACT FROM AUTHOR]

Zebrafish has become a popular research model in the last years, and several diseases affecting zebrafish research facilities have been reported. However, only one case of naturally occurring viral infections was described for this species. In 2015, infectious spleen and kidney necrosis virus (ISKNV) was detected in zebrafish from a research facility in Spain. Affected fish showed lethargy, loss of appetite, abnormal swimming, distention of the coelomic cavity and, in the most severe cases, respiratory distress, pale gills and petechial haemorrhages at the base of fins. Cytomegaly was the most relevant histopathological finding in organs and tissues, sometimes associated to degenerative and necrotic changes. ISKNV belongs to the relatively newly defined genus Megalocytivirus, family Iridoviridae, comprising large, icosahedral cytoplasmic DNA viruses. This is the first case of naturally occurring Megalocytivirus infection in zebrafish research facilities, associated with morbidity. The virus has been identified based on both pathologic and genetic evidence, to better understand the pathogenesis of the infection in zebrafish and the phylogenetic relationship with other iridoviruses. Given the ability of megalocytiviruses to cross-species boundaries, it seems necessary to implement stringent biosecurity practices as these infections may invalidate experimental data and have major impact on laboratory and cultured fish. [ABSTRACT FROM AUTHOR]

Several Chlamydiales families are associated with epitheliocystis, a common condition of the fish gill epithelium. These families share common ancestors with the Chlamydiaceae and environmental Chlamydiae. Due to the lack of culture systems, little is known about the biology of these chlamydial fish pathogens. We investigated epitheliocystis in cultured Orange-spotted grouper ( Epinephelus coioides) from North Queensland, Australia. Basophilic inclusions were present in the gills of 22/31 fish and the presence of the chlamydial pathogen in the cysts was confirmed by in situ hybridization. Giant grouper ( Epinephelus lanceolatus) cultured in the same systems were epitheliocystis free. 16S rRNA gene sequencing revealed a novel member of the Candidatus Parilichlamydiaceae: Ca. Similichlamydia epinephelii. Using metagenomic approaches, we obtained an estimated 68% of the chlamydial genome, revealing that this novel chlamydial pathogen shares a number of key pathogenic hallmarks with the Chlamydiaceae, including an intact Type III Secretion system and several chlamydial virulence factors. This provides additional evidence that these pathogenic mechanisms were acquired early in the evolution of this unique bacterial phylum. The identification and genomic characterization of Ca. S. epinephelii provides new opportunities to study the biology of distantly-related chlamydial pathogens while shining a new light on the evolution of pathogenicity of the Chlamydiaceae. [ABSTRACT FROM AUTHOR]

In addition to being the respiratory organ in fish, the gills form a barrier against the external milieu. Innate and adaptive immune system components have been detected in the gills, but lymphoid cell accumulations similar to that seen in the mammalian mucosa have not been described. The present investigations revealed cell accumulations on the caudal edge of interbranchial septum at the base of the gill filaments in the Atlantic salmon. Cytokeratin immunohistochemical staining and identification of a basal membrane and desmosome cell junctions by electron microscopy showed that the cell accumulation was located intraepithelially. Major histocompatibility complex (MHC) class II+ cells were detected by immunohistochemistry, and laser capture micro-dissection and subsequent RT-PCR analysis revealed expression of T-cell receptor transcripts in the investigated tissue, suggesting the presence of T cells. The intraepithelial tissue reported here may be a suitable location for immune surveillance of gill infections, as well as a target site for new vaccine approaches and investigations of epithelial immunity. This is the first description of a lymphocyte cell aggregation within a teleostian gill epithelium network, illustrating a phylogenetically early form of leukocyte accumulations in a respiratory organ. [ABSTRACT FROM AUTHOR]

Global distribution of platyhelminth parasites and their host specificities are not well known. Our hypothesis was that platyhelminth parasites of large pelagic fishes are common around the world. We analysed molecular variation in three different taxa of platyhelminth parasites infecting four species of tunas: yellowfin tuna ( Thunnus albacares, Scombridae) from Western Australia, southern bluefin tuna ( Thunnus maccoyii, Scombridae) from South Australia, Pacific bluefin tuna ( Thunnus orientalis, Scombridae) from Pacific Mexico and northern bluefin tuna ( T. thynnus, Scombridae) from two localities in the Mediterranean (Spain and Croatia). Comparisons of ITS2 and partial 28S rDNA demonstrated two congeneric species of blood flukes (Digenea: Sanguinicolidae) from multiple hosts and localities: Cardicola forsteri from southern bluefin and northern bluefin tunas, and Cardicola sp. from Pacific bluefin and northern bluefin tunas; and a gill fluke, Hexostoma thynni (Polyopisthocotylea: Hexostomatidae), from yellowfin, southern bluefin and northern bluefin tunas. Partial 28S rDNA indicates that a second type of fluke on the gills, Capsala sp. (Monopisthocotylea: Capsalidae), occurs on both southern bluefin and Pacific bluefin tunas . This appears to be the first report of conspecific platyhelminth parasites of teleosts with a wide-ranging geographical distribution that has been confirmed through molecular approaches. Given the brevity of the free-living larval stage of both taxa of flukes on the gills ( H. thynni and Capsala sp.), we conclude that the only feasible hypothesis for the cosmopolitan distribution of these flatworms is migrations of host tunas. Host migration also seems likely to be responsible for the widespread occurrence of the two species of blood flukes ( Cardicola spp.), although it is also possible that these were translocated recently by the spread of infected intermediate hosts. [ABSTRACT FROM AUTHOR]

Official government census takers tick the religion box titled 'none' when they fill out the forms for most Orang Asli. Yet at weddings and other festivities, the Hma' Btsisi', an indigenous Mon-Khmer speaking people of Peninsular Malaysia, perform a religious dance and song cycle called the main jo'oh. Today, in Malaysia, the main jo'oh is a government centrepiece for Oreng Asli culture. Btsisi' are frequently asked to perform the main jo'oh for the Malaysian public and for tourists. The main jo'oh is displayed as a curious, albeit beautiful and exotic performance by a heathen people who have 'no' religion. But this paper points out that the dance is far from being solely an exotic relic. I argue that the meanings embodied in the dance performance form the foundation of Btsisi' beliefs; in other words, their religion. I conclude by discussing the main jo'oh in the modern Btsisi' and national context In particular, I demonstrate that the main jo'oh is a way for the Btsisi' to identify and distinguish themselves from other Orang Asli communities as well as from the majority Malay population. [ABSTRACT FROM AUTHOR]

The editorial and management team of the Journal of Fish Diseases is pleased to introduce readers to a new initiative commencing with the publication of a peer-reviewed I Invited Manuscript i : "Review of diseases and health management in zebrafish I Danio rerio i (Hamilton 1822) in research facilities" by Kent et al., found within this issue of the JFD. The fish health community that supports the JFD includes researchers in many disciplines, working on many different species, and derives from interests in all parts of the world. JFD authorship and readership are at the forefront of fish health sciences, and feedback on this I Invited Review Series i initiative is welcomed. [Extracted from the article]

Limited visibility in the underwater environment often restricts opportunities for archaeological prospection. Especially in reservoirs with a high content of suspended solids, methods based on acoustics prove to be extremely useful. This study represents the first high‐resolution acoustic mapping and archaeological prospections of the Old Oder Canal, which has extremely poor visibility. The study site is located near the town of Krosno Odrzańskie in Poland. The town is one of the country's most significant river crossings and settlements of mediaeval origin (including its wooden bridges). The following research objectives were identified: (1) exploration of the Old Oder Canal, including underwater acoustics and archaeological prospections; (2) analysis and interpretation of the study area based on acquired datasets; and (3) evaluation of secondary features of the river bathymetry for identification of archaeological objects. Possible locations of archaeological objects were determined based on analysis and interpretation of multibeam echosounder measurements of the riverbed. Fieldwork allowed structural elements of mediaeval bridges to be found and dendrochronological sampling performed. Feature selection analyses allowed the determination and evaluation of geomorphometric attributes, combining the characteristics of the discovered objects and diagnostics in order better to differentiate archaeological remains. Proposed secondary features may facilitate archaeological explorations in difficult environments. [ABSTRACT FROM AUTHOR]