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Aims: Develop a species‐specific multiplex PCR to correctly identify Edwardsiella species in routine diagnostic for fish bacterial diseases. Methods and Results: The genomes of 62 Edwardsiella spp. isolates available from the National Center for Biotechnology Information (NCBI) database were subjected to taxonomic and pan‐genomic analyses to identify unique regions that could be exploited by species‐specific PCR. The designed primers were tested against isolated Edwardsiella spp. strains, revealing errors in commercial biochemical tests for bacterial classification regarding Edwardsiella species. Conclusion: Some of the genomes of Edwardsiella spp. in the NCBI platform were incorrectly classified, which can lead to errors in some research. A functional mPCR was developed to differentiate between phenotypically and genetically ambiguous Edwardsiella, with which, we detected the presence of Edwardsiella anguillarum affecting fish in Brazil. Significance and Impact of the Study: This study shows that the misclassification of Edwardsiella spp in Brazil concealed the presence of E. anguillarum in South America. Also, this review of the taxonomic classification of the Edwardsiella genus is a contribution to the field to help researchers with their sequencing and identification of genomes, showing some misclassifications in online databases that must be corrected, as well as developing an easy assay to characterize Edwardsiella species in an end‐point mPCR. [ABSTRACT FROM AUTHOR]

The dermocistidiosys is a new fish disease in the Brazilian aquaculture. This is the second report occurred in Pangasionodon hypophthalmus in Brazil, but therapeutic alternatives to controlling it still are missing. The objective of this study was to characterize the Dermocystidium spp. infection in P. hypophthalmus fingerling and to evaluate different alternatives for controlling it. A total of 170 fish naturally infected with Dermocystidium spp. were used in this study. The fish were anesthetized and then submitted to blood and parasitological analysis. The glucose, total of erythrocytes, hematocrit percentage, hemoglobin concentration, hematimetric indexes, thrombocytes and differential of leukocytes were evaluated. In vitro tests were performed exposing Dermocystidium spp. cysts at to different therapeutic products: copper nanoparticles (CuNP), zinc sulphate (ZnSO 4), copper sulphate (CuSO 4), plant aqueous extract of Costus spicatus and Schinus terebinthifolia. The plasmodium viability (live/dead) were evaluated by fluorescent probes. Afterwards, an in vivo assay was carried out using the same therapeutic products plus one treatment represented by elevating temperature (32o C) during 96 h, evaluating the clinical signs and mortality. After 96 h, the surviving fish were monitored for more 60 days. The infected fish before experiments, presented discolored skin areas and a worm-like elongated cysts (plasmodium) within vesicles randomly distributed through the body, showing mean intensity of 80.70 ± 23.46 cysts/infected fish and the neutrophil was the most abundant cell in the blood. All therapeutic products caused mortality of spores within cysts in vitro assay. However, for in vivo test, despite the efficacy in vitro, fish died after exposure to treatments, except to elevating temperature. The fish into the controlled temperature strategy demonstrated 100% of survival at the end of 96 h and absence of clinical signs after 60 days. • Different therapeutic products in vitro to determine viability of the cysts. • Different treatments in vivo to control the infection by Dermocystidium in fish. • Controlled temperature can ensure the survival and backtracking clinical signs of the infection by Dermocystidium. [ABSTRACT FROM AUTHOR]

The present study describes Coccomyxa bragantinensis n. sp., which was found parasitising the gallbladder of the Coco Sea catfish, Bagre bagre, captured off Ajuruteua beach, in the region of Bragança in Pará state, northern Brazil. Most (77.5%) of the 40 fish specimens examined (31/40) had myxospores floating in the bile liquid. These spores are partially ellipsoid, with a tapering anterior extremity and a rounded, elongated posterior extremity with a single piriform polar capsule containing a helicoidal polar filament, with 5-6 coils. A partial sequence of 957 bp of the SSU rDNA gene was obtained from the specimens and deposited in GenBank (xxx). The new species described here - Coccomyxa bragantinensis n. sp. - is phylogenetically similar to Coccomyxa morovi, although it differs from all the other Coccomyxa species and is the first species of this genus to be described from Brazil on the basis of molecular evidence., Competing Interests: Declaration of Competing Interest The authors have no competing of interests to declare., (Copyright © 2023. Published by Elsevier B.V.)

A new and two previously described species of Ameloblastella Kritsky, Mendoza-Franco & Scholz, 2000 were found in the gills of two pimelodid catfishes from the Tocantins River, Maranhão State, Brazil: Ameloblastella prima n. sp. from Pimelodina flavipinnis Steindachner, and A. edentensis Mendoza-Franco, Mendoza-Palmero & Scholz, 2016 and A. peruensis Mendoza-Franco, Mendoza-Palmero & Scholz, 2016 from Hypophthalmus marginatus Valenciennes. The new species differs from its congeners by having an accessory piece tubular, covered by a delicate membranous cap at 2/3 of the length, by the shape of the ventral and dorsal anchors, in which the ventral anchor is represented by a curved shaft in a position of 80° degrees, with delicate ornamentations located at the superficial and deep root areas, and the dorsal anchor with a long, well-developed and convex superficial root and short deep root, also presenting delicate ornamentations at the superficial and deep root areas. The present study provides new biogeographical data on the two previously described species of Ameloblastella and improves the knowledge on the species of Monogenoidea from the Neotropical Region, increasing to 14 the number of known species of Ameloblastella for this region., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Copyright of Acta Veterinaria Brasilica is the property of Acta Veterinaria Brasilica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oncoceratium n. gen. is proposed to accommodate Oncoceratium amphidactylum n. gen. n. sp. (Monogenoidea, Gyrodactylidae). Although the proposed genus is monotypic, the differences presented in the diagnosis clearly establish it as distinct from species from other genera, such as Gyrodactylus von Nordmann, 1832 and especially those that occur exclusively in the Neotropical region. The new genus is diagnosed by the presence of a bulbous male copulatory organ, with one row of spinelets of similar sizes and shapes, while the only spine usually found in the gyrodactylids is absent or not differentiated; a haptor with anchors presenting points folded outwards, and superficial and deep roots continuous and indistinguishable; the absence of a deep bar; and hooks in two bilateral clusters of eight hooks. Oncoceratium amphidactylum n. gen. n. sp. is described from the tamboatá fish, Hoplosternum littorale (Hancock) (Callichthyidae), and is characterized by the presence of a pair of horn-shaped anchors with the point turned outwards, a superficial bar shield and absent deep bar, hooks disposed in bilateral lobes, and a MCO with no spine or with a row with large spinelets visible in place of the spine. In addition to the morphological features, distance analysis and Bayesian inference, based on 5.8s and partial ITS2, support placing the new species in a new genus, and not including it in a cluster of species of Gyrodactylus and near to Gyrodactyloides bychowskii Albova, 1948, Ieredactylus rivuli Schelkle et al., 2011 and Laminiscus gussevi (Bychowsky & Polyansky, 1953) Pálsson & Beverely-Burton, 1983., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

The dactylogyrid genus Rhinoxenus (Monogenea: Dactylogyridae) is composed of specialized monogeneans infecting the nasal cavities of freshwater fishes from the Neotropical region. This taxon currently comprises 11 species and is easily distinguished from other monogeneans by the absence of the dorsal bar, ventral anchor with inconspicuous roots covered by a sclerotized cap, dorsal anchor greatly modified into a needle-like shape, and hook pair 2 located into bilateral lobes of the trunk. Specimens of Rhinoxenus euryxenus and Rhinoxenus paranaensis were found infecting the nasal cavities of Serrasalmus marginatus and Serrasalmus maculatus, respectively, from the Paraná River basin in Brazil. For the first time, molecular data of Rhinoxenus spp. were obtained and used as a basis for phylogenetic analyses of the genus. Furthermore, our findings represent the first record of R. paranaensis in Brazil., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Francisella noatunensis orientalis is a bacterium that causes emerging bacteriosis in Nile tilapia ( Oreochromis niloticus) in many parts of the world, including Brazil. It is a non-motile, Gram-negative, strictly aerobic, facultative intracellular coccobacillus. This species of bacteria is responsible for low to high mortality in fish farms, causing economic losses for fish farmers. This study aimed to detect the presence of F. noatunensis orientalis using qPCR (real-time polymerase chain reaction) and to describe lesions caused by the bacterium in O. niloticus in Brazilian aquaculture. For this purpose, 360 fish from six fish farms (30 per farm) were sampled at two time points ( n = 180 per sampling). Necropsies and histopathology were performed for lesion observation, in addition to qPCR and sequencing for detection and identification of Francisella species. Environmental data were collected using a multiparameter sonde YSI EXO2. All measured limnological variables were within the optimum range for cultivation of Nile tilapia. The major lesions present were melanization of the skin, splenomegaly, granulomas, and inflammatory cell responses. The prevalence of francisellosis varied from 0 to 86.66% between time periods and fish farms analyzed, and an outbreak was observed during the second sampling period. This study describes the prevalence of francisellosis in O. niloticus and reports that the lesions found are not exclusively associated with this bacterial disease. [ABSTRACT FROM AUTHOR]

In this study, a new dactylogyrid species is described from the gills of two ariid fish species of the Brazilian coast, Genidens barbus and Genidens genidens , by combining morphological characters with partial 18S rDNA sequences. The new species can be distinguished from its congeners by the following morphological characteristics: a male copulatory organ (MCO), a coiled tubular shaft of around one counterclockwise ring, base with a sclerotized cap; MCO with tapered distal region; a T-shaped accessory piece; a vagina, a cup-shaped vaginal vestibule, slightly sclerotized; and a pharynx comprising a muscular, glandular bulb. Supplementary taxonomic data for Chauhanellus velum from Sciades couma (type-host) are also presented and new 18S rDNA sequences of Chauhanellus spp. from other ariid fish from South America are provided. Phylogenetic analyses based on partial 18S rDNA gene sequences placed Chauhanellus riograndinensis n. sp. and Chauhanellus velum as two early divergent lineages within Chauhanellus from South America. Finally, a way to test the monophyly of Chauhanellus and Hamatopeduncularia is also discussed, which may be useful for future studies.

Haemulidae represents one of the most diverse, widespread and conspicuous families of Perciformes, in which most species are marine, some brackish and rarely from freshwater. From April 2009 to July 2012, 120 specimens of Conodon nobilis, 60 Orthopristis rubra and 50 Anisotremus virginicus were collected off the State of Rio de Janeiro, Brazil, and analyzed for metazoan parasites. A total of 16 parasite taxa were found on/in A. virginicus, 19 on/in Co. nobilis and 21 on/in O. rubra, in which ectoparasites were most common on A. virginicus and Co. nobilis and endoparasites in O. rubra. All parasites showed aggregate pattern of distribution (discrepancy index values higher than 0.70). Mean abundance, species richness and Brillouin index (diversity) differed among the host species, i.e., O. rubra showed the highest values, followed by A. virginicus and Co. nobilis with intermediate and lowest values, respectively. At infracommunity level was possible to observe high similarity of parasite composition among the three host species. The digeneans Leurodera decora and Monorchis latus, and the acanthocephalan Koronacantha sp. represent new locality records off Brazil. Moreover, five, four and two taxa are reported, for the first time, parasitizing Co. nobilis, A. virginicus and O. rubra, respectively.

Raphidascarid nematodes have been the focus of several studies, mainly due to the zoonotic potential of some species, even though the cases are underreported. Due to the difficulty in identifying their larvae, the use of diagnostic techniques involving morphological and molecular analyses has grown in the last 20 years. The present study had as objective the morphological and molecular characterization of the L3 larval types of Hysterothylacium collected in Pomatomus saltatrix and Pagrus pagrus from the Brazilian coast, close to the municipality of Santos, State of São Paulo. Twenty specimens of P. saltatrix were necropsied and Hysterothylacium type V (n = 257) and Hysterothylacium type X (n = 5) larvae were found. Five specimens of P. pagrus were necropsied and all were parasitized by Hysterothylacium type V larvae. The analyses showed a genetic proximity relationship between Hysterothylacium types V with other Hysterothylacium V and with H. deardorffoverstreetorum, although this is a species inquirenda. Haplotypes for Hysterothylacium type X found in the present study formed a monophyletic group with other Hysterothylacium X, H. amoyense, and H. zhoushanense. Through this study, new hosts and localities were registered for Hysterothylacium type V and Hysterothylacium type X.

Cyprinid herpesvirus 3 has a worldwide distribution and presents high mortality rates in species of Cyprinus carpio, causing serious economic loss to the global aquaculture industry. The description of this infection in other ornamental fish species is still limited. For this purpose, 100 ornamental fish from 24 different species were tested by PCR for Cyprinid hespesvirus 3 and the positive samples represented 6% of the tested samples. Phylogenetic reconstruction, based on the Thymidine Kinase gene, revealed the existence of two distinct clades. One clade grouped a Brazilian sample with European and Asian genotypes of CyHV-3 and a second clade, containing only Brazilian sequences described in this study. All of the Brazilian sequences showed identity values greater than 97.7% when compared to each other. This is the first report of the occurrence of Cyprinid herpesvirus 3 in ornamental fish species in Brazil. These results in association with further studies of viral isolation and characterization can help in establishing effective surveillance and disease control program., (© 2022. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Fingerlings of Oreochromis niloticus collected in an artificial urban lake from Belo Horizonte,Minas Gerais, Brazil, were evaluated for natural infection with trematodes. Morphological taxonomic identification of four fluke species was performed in O. niloticus examined, and the total prevalence of metacercariae was 60.7% (37/61). Centrocestus formosanus, a heterophyid found in the gills, was the species with the highest prevalence and mean intensity of infection (31.1% and 3.42 (1-42), resp.), followed by the diplostomid Austrodiplostomum compactum (29.5% and 1.27 (1-2)) recovered from the eyes. Metacercariae of Drepanocephalus sp. and Ribeiroia sp., both found in the oral cavity of the fish, were verified at low prevalences (8.2% and 1.6%, resp.) and intensities of infection (only one metacercaria of each of these species per fish).These species of trematodes are reported for the first time in O. niloticus from South America.The potential of occurrence of these parasites in tilapia farming and the control strategies are briefly discussed. [ABSTRACT FROM AUTHOR]

In June 2020, an atypical fatal outbreak in a Brazilian Nile tilapia farm was investigated. Twenty-three animals were collected and different tissues were used for bacterial isolation, histopathological and electron microscopic examination and viral detection using molecular methods. A large number of megalocytes were observed in the histopathological analysis of several tissues. Icosahedral virions, with a diameter of approximately 160 nm, were visualized inside the megalocytes through transmission electron microscopy of the spleen tissue. The virions were confirmed to be infectious spleen and kidney necrosis virus (ISKNV) through PCR and sequencing analyses of the fish samples. Phylogenetic analysis indicated that the virus belongs to the Clade 1 of ISKNV. This viral pathogen is associated with high mortality in the early stages of cultured Nile tilapia in the United States, Thailand and Ghana; however, until now, there have been no reports from ISKNV affecting cultured fish in Brazil. Additionally, in 14 out of 23 sampled fish, Streptococcus agalactiae, Edwardsiella tarda or Aeromonas hydrophila infections were also detected. This is the first report of fatal ISKNV infections in the Brazilian Nile tilapia fish farms and represents a new challenge to the aquaculture sector in the country., (© 2021 Wiley-VCH GmbH.)

Nontuberculous mycobacteria infection is one of the most common chronic bacterial diseases in ornamental aquarium fish and appears to be directly related to stressful husbandry practices. Furthermore, it also represents zoonotic potential. Here we present the isolation and characterization of non-tuberculous mycobacteria from diseased freshwater angelfish (Pterophyllum scalare) in São Paulo, Brazil. Nine discarded breeding females with signs of disease were evaluated. The fish exhibited lethargy, loss of appetite, cachexia, skin ulcers, and exophthalmia. At necropsy, four fishes presented macroscopic granulomas in the spleen. Mycobacterium chelonae, M. fortuitum, M. gordonae, M. intracellulare and M. peregrinum were isolated and identified by hsp65 PCR restriction analysis. Histopathological analysis revealed microscopic lesions compatible with mycobacteriosis, and Mycobacterium bacillus were observed by Ziehl-Neelsen stain. Notably, all Mycobacterium species identified in this study have already been reported in human patients; therefore, diseased animals may be a source of infection for people who handle fish and aquariums.

We describe Myxobolus cataractae n. sp., found parasitizing Imparfinis mirini from Cachoeirinha stream, a tributary of Pardo River, Paraná River basin, municipality of Botucatu, São Paulo State, Brazil. We based the description on myxospore morphology, histology, and small subunit ribosomal DNA partial sequences. Whitish and elongated mass of myxospores were found in gill filaments, occupying an intrafilamental position. The myxospores were slightly ellipsoidal and the morphometric measurements revealed a myxospore body length of 7.8 ± 0.4 μm; myxospore width of 5.9 ± 0.4 μm; and thickness of 3.9 ± 0.3 μm. The polar capsules are equal in size and measured 3.5 ± 0.2 μm in length and 1.7 ± 0.2 μm in width. The polar tubules had 6-7 coils. Myxobolus cataractae n. sp. is classified as the intrafilamental type and chondreal subtype by the histological analysis of gills. Phylogenetic analysis showed a well-supported subclade formed by species that parasitize gills of Siluriformes, with M. imparfinis as a sister species of Myxobolus cataractae n. sp. Using molecular and morphological characterization, this cryptic species was identified as a new species of the genus Myxobolus., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses a study on spores of a new myxosporidian called H. torpedo sp. nov., which parasitizes the nervous system of a Brazilian fish from the Amazonian region. Specimens of the freshwater fish Brachyhypopomus pinnicaudatus or "itui tuanga" were collected from Peixe Boi River of the lower Amazon River in the State of Pará northeastern Brazil and sampling was carried for the period January and February 2010. The characteristics observed confirmed the morphological similarities of the spores of the different species of the genus Hennuguya. It notes the establishment of the species Henneguya torpedo sp. nov. indicated as the first to be recorded in the brain and spinal cord of Brazilian teleost fishes.

Abstract: From February to October 2007, thirty specimens of the king mackerel, Scomberomorus cavalla (Cuvier, 1829) were purchased from markets in the municipalities of Niterói and Rio de Janeiro. The fishes were measured, filleted and further had their organs investigated for helminths. Ten out of the thirty fish specimens were parasitized with anisakid nematodes represented by Anisakis sp. and Contracaecum sp. with prevalence of 1% and 16%, mean intensity of 2 and 3.31 and mean abundance of 0.02 and 0.53, respectively. The infection range with Contracaecum sp. was 1–9. The sites of infection were the stomach serosa and mesentery. Seventeen fish specimens (53%) out of the 30 investigated were parasitized with Trypanorhyncha metacestodes, identified as Callitetrarhynchus gracilis, Pterobothrium crassicole, Callitetrarhynchus speciosus and Tentacularia coryphaenae in the mesentery, with prevalence of 26, 20, 6, 3%, intensity and mean intensity of 3.25, 3.5, 1, 2 and mean abundance of 0.86, 0.7, 0.06 and 0.06, respectively. The infection range due to C. gracilis and P. crassicole were of 1–5 and 1–20, respectively. Anisakis sp., C. speciosus and P. crassicole are reported in S. cavalla for the first time. Considerations on the zoonotic potential of the parasites and their rules in sanitary inspection are presented. [ABSTRACT FROM AUTHOR]

This study was aimed at evaluating the infection levels of Austrodiplostomum compactum metacercariae in 378 specimens of Plagioscion squamosissimus ('corvina' or 'pescada branca') from the Nova Avanhandava reservoir, low Tietê River, São Paulo State, Brazil. High prevalence, mean intensity of infection and abundance were observed in P. squamosissimus during most of the study, with the exception of March 2004. The relative condition factor (Kn) did not differ between parasitized and non-parasitized fish. A statistically significant positive correlation was observed between host standard length and intensity of infection. The analysis of biotic and abiotic variables showed that no abiotic variable correlated with parasitic infection levels. Moreover, P. squamosissimus status was demonstrated to be unaffected by A. compactum metacercariae infection. [ABSTRACT FROM AUTHOR]

The article discusses research on the ecological aspects of metazoan endoparasites of Metynnis lippincottianus from the Upper Paraná River floodplain in Brazil. Of the 44 specimens of M. lippincottianus, 72.7 percent of fishes were infected by at least one species of helminth endoparasites, including Dadayus pacupeva, Spinoxyuris oxydoras, Contracaecum, Procamallanus inopinatus and Raphidascaris mahnerti. It was also observed that the parasite community was dominated by D. pacupeva and S. oxydoras having the highest values of prevalence, mean density and abundance. Findings reveal the potential of aggregation as a life strategy of the parasite to maximize fitness as well as the absence of correlation between parasitism and sex.

The article presents a research describing the spread of ranaviruses which affects the mortality events in amphibians, fish, and reptiles. The study aims to characterize the virus isolated from sick R. catesbeiana tadpoles and indicate the etiology of these outbreaks. Examined were sick tadpoles collected from three farms located in Goiás State, Brazil from 2003 to 2005. These species were processed for virus isolation and characterization, microbiology, histopathology, and parasitology. Observations suggested that viruses of family Iridoviridae, genus Ranavirus, are pathogenic to young Rana catesbeiana tadpoles and the potential cause of mass mortality commonly observed on Brazilian frog farms.

Abstract: There are many diseases of fish, livestock and companion animals that impact negatively on animal health, welfare and productivity and for which there are no effective vaccines. The development of new vaccines is reliant on the availability of well-characterised immunological tools and reagents to understand host–pathogen interactions and identify protective immune responses. Veterinary immunology has always lagged behind mouse and human immunology in terms of development and availability of tools and reagents. However, several initiatives are underway to address this. The Veterinary Immunology Committee (VIC) Toolkit was initiated 6years ago at the sixth International Veterinary Immunology Symposium (IVIS) in Uppsala and in the intervening period there have been several notable developments that have advanced reagent development and information exchange. This review will discuss advances in veterinary reagent development, networks, databases and commercial availability with particular reference to the second VIC Toolkit workshop held at the eighth IVIS in Ouro Preto, Brazil on the 15th of August 2007. [Copyright &y& Elsevier]

This study assessed the use of increasing levels of brown propolis extract (BPE) as a growth promoter in Nile tilapia fingerling feeds. In a complete randomized design, 75 Nile tilapia fingerlings with 60 days on average and weighing 4.1±0.1 g were assigned to 25 aquaria (60 L) and subjected to 5 treatments in 5 repetitions for 30 days. Propolis from Serra do Araripe, Cariri Region, South Ceará State – Brazil was used to produce the BPE. The treatments involved the addition of BPE to feed samples (0.91, 1.83, 2.74 and 3.65 g kg−1) and feed control (without BPE). The final mean weight and the percentage of weight gain varied quadratically with the increase in BPE ( P<0.01), with a maximum of 2.22 g kg−1. The other evaluated parameters were not affected by the treatments ( P>0.05). The level of best performance parameters was 2.22 g kg−1, between the levels of 1.83 and 2.74 g BPE kg−1 feed inclusion. These results indicate the potential to use the brown propolis extract as a growth promoter to Nile tilapia fingerlings. [ABSTRACT FROM AUTHOR]

Abstract: The minimum inhibitory concentration (MIC) and diameter of zone of inhibition of florfenicol (FLO) and the MIC of bicyclomycin (BCM) were determined for 118 motile aeromonad strains isolated from diseased fish and pond water in Brazil. Tests were performed according to Clinical and Laboratory Standards Institute guidelines. FLO MIC values ranged from 0.5 to 16 μg/mL and BCM MIC values from 0.78 to 100 μg/mL. According to MIC frequency distributions, the strains were classified as wild-type (WT) and non-wild-type (NWT) and provisional epidemiological cutoff values for FLO (WT ≤4 μg/mL) and BCM (WT ≤6.25 μg/mL) were estimated. Disk susceptibility tests revealed a provisional epidemiological cutoff of WT ≥23 mm for FLO. The lack of groups of bacterial strains with NWT behavior to FLO and BCM suggests that the estimated cutoffs should be revised in the future. Both antibiotics exhibited high efficacy in vitro against motile aeromonad strains. [Copyright &y& Elsevier]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genetic variability among Streptococcus agalactiae isolates recovered from fish was characterized using single-stranded conformation polymorphism (SSCP) analysis of the intergenic spacer region (ISR), and amplified fragment length polymorphism (AFLP) fingerprinting. A total of 46 S. agalactiae cultures isolated from different fish species and geographic origins as well as related reference strains were included in the study. ISR-SSCP divided the S. agalactiae isolates analysed into five distinct genotypes. Genotype 1 grouped all Kuwait isolates while genotype 4 clustered the majority of non-Kuwait isolates (USA, Brazil and Honduras). AFLP analysis offered a higher resolution level by dividing the isolates into 13 different genotypes. Two different AFLP profiles were identified within the Kuwait isolates. When data from both ISR-SSCP and AFLP were combined through a multidimensional analysis (MDS), a good correlation between geographical origin and genotypes was observed. Both AFLP and ISR-SSCP revealed genetic differences between S. agalactiae isolates from fish. While AFLP offered a higher resolution, ISR-SSCP also provided valid information being a simpler and faster method. [ABSTRACT FROM AUTHOR]

Purpose: The class Myxozoa consists of microscopic spores that typically present uniform morphological simplifications, containing one or two sporoplasms surrounded by valve cells. The present study analysed the morphological and phylogenetic characteristics of what proved to be a new species of Ceratomyxa found in the gallbladder of Mesonauta festivus Heckel, 1840 captured on the Piririm River in the municipality of Macapá, in Amapá state, Brazil., Methods: The fish were collected in gillnets, and were transported alive to Amapá State University in Macapá for the analysis of the organs. Crescent- or arch-shaped free spores were observed under light microscopy, containing two polar capsules and a suture line, which is typical of the morphology of the genus Ceratomyxa, contained within plasmodia that had snake-like movements. The gallbladder was conserved in 80% alcohol for the analysis of the 18S rDNA gene, and in Davidson solution for standardhistology., Results: Ceratomyxa spores (n = 20) were observed in 11 of the 50 samplesanalysed, and thus had a prevalence of 22%, and had a mean length of 4.2 ± 0.5 µm, mean thickness of 22.75 ± 0.3 µm, and two polar capsules, 1.86 ± 0.3 µm long and 1.63 ± 0.1 µm thick., Conclusions: The phylogenetic analysis indicated that the new species forms a cluster with other freshwater Amazonian Ceratomyxa species, described previously. The new species represents the first description of a taxon of the genus Ceratomyxain fish from the Brazilian state of Amapá., (© 2021. Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

Although morphological abnormalities in several rays and skate species around the American continents have frequently mentioned, their numbers are unknown. The present work record morphological abnormalities in four Urotrygonidae species. Two anophthalmic specimens were detected (Urotrygon microphthalmum and Urobatis halleri). Two individuals lacked caudal fins (Urobatis maculatus and Urotrygon chilensis). Two round rays showed incomplete fusion of the pectoral fin to the head (U. microphthalmum and U. chilensis). Vertebral compression and fusion were found in a 6-year-old female Urotrygon rogersi. In addition, 118 abnormal batomorph specimens were gathered from the available bibliography, spanning the last six decades (1959-2021). Amblyraja doellojuradoi was the species with the highest number of abnormalities (18). The most common anomaly was an incomplete fusion of the pectoral fin with the head. Since 2010, at least 30 anomalous batomorphs have been recorded every 5 years. Sixty-nine abnormal specimens occurred in the Northern Hemisphere (1.00-60.00 N). The Cortezian (Pacific) and Southeastern Brazil (Atlantic) marine ecoregions stood out with the highest number of these specimens. Mexico recorded 58 anomalous specimens, followed by Brazil (n = 36). Biological, abiotic and anthropogenic factors are probably the leading causes. However, additional studies are necessary to elucidate these speculations., (© 2021 John Wiley & Sons Ltd.)

Although species of the genus Ceratomyxa Thélohan, 1892 mostly parasitize marine fish around the world, a surprising diversity of the genus has recently been reported from Amazonian freshwater fish. In this study, we report a freshwater Ceratomyxa species parasitizing Hemiodus orthonops (Hemiodontidae) from the Paraná River (La Plata Basin) in a watershed flowing into the southern part of South America, which expands the geographic distribution of this fish parasite in the freshwater resources of the continent. We applied a combination of morphological, small subunit ribosomal DNA (SSU rDNA), and phylogenetic analyses, and vermiform-shaped plasmodia endowed with motility were found swimming in the bile of the fish. The characteristics of the plasmodia and myxospores of the Ceratomyxa species found in the Paraná River resembled those of Ceratomyxa fonsecai, a parasite of the congeneric host Hemiodus unimaculatus from the Tocantins River basin in northern Brazil. Due to the close morphological and morphometric resemblances and the impossibility of genetic comparison, the parasite found in H. orthonops from the Paraná River was designated as Ceratomyxa cf. fonsecai, and the definition of its taxonomic status was left for further study. Maximum likelihood and Bayesian analyses showed Ceratomyxa cf. fonsecai clustering within a well-supported clade, together with other Amazonian freshwater ceratomyxids. The present study suggests that shifts of the complex host/parasite between marine and freshwater environments were facilitated by marine incursions into South America in the Early Miocene., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Urocleidoides spp. are reported from the gills of 20 specimens of Parodon nasus (standard length 8.512 cm), from the Indiana stream, Tiet River, Upper Paran River basin, municipality of Botucatu, So Paulo State, Brazil. Urocleoidoides tenuis and two new species were found. Urocleidoides indianensis n. sp. differs from its congeners mainly by the morphology of the vaginal sclerite that is robust, sickle-shaped, and forked at the distal end; and by the bulbous-shaped accessory piece of the male copulatory complex. Urocleidoides parodoni n. sp. resembles U. tenuis by presenting male copulatory organ with approximately 7 counterclockwise rings, but differs by the morphology of the accessory piece (lobate with a small hook-like projection versus pincer-shaped), vaginal sclerite (thumb-like subterminal projection vs. presence of a distal hook), vaginal tube (conspicuously sclerotized vs. slightly sclerotized), shape of the ventral bar (bowed vs. wide V-shaped), ventral and dorsal anchors (robust base and short shaft vs. considerably less robust base and long shaft), and hooks (slender shank with a weakly sclerotized subunit at base vs. dilated shank). Sequences of the partial 28S rDNA gene of the dactylogyrids found in this study are provided. Phylogenetic analyses showed Urocledoides spp. from Parodontidae clustering together with strong support values. This study increases the number of valid Urocleidoides species to 39, and the number of species described from parodontid hosts to four.

In this study, integrative taxonomy is applied to describe a new dactylogyrid species, Ameloblastella pirarara sp. n. from the gills of Phractocephalus hemioliopterus, a commercially and ecologically important Amazonian catfish. Ameloblastella pirarara sp. n. can be distinguished from its congeners mainly by the morphology of the male copulatory organ (MCO), accessory piece, and anchors. The new species most resembles Ameloblastella unapi, from the Peruvian Amazon, but differs from it by the number of MCO rings, morphology of the vaginal canal and sclerotized structures of the haptor. Phylogenetic analyses based on sequences of the partial 28S rDNA (D1-D2 domains) gene placed the new species in a well-supported subclade of Ameloblastella spp. parasites of Neotropical siluriform fish, as a sister taxon to Ameloblastella unapioides. Thus, the new species described herein expands our knowledge of the diversity of monogenoid parasites from Amazonian freshwater fish., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The present study describes the morphological, histopathological and SSU rDNA data of a new myxosporean species infecting farmed Astyanax lacustris fish from the state of São Paulo, Brazil. Henneguya lambariensis sp. nov. was found infecting the gills, and the plasmodial development resulted in displacement, blood congestion, compression, deformation and lamellar fusion, stretching of the epithelia, hyperplasia of the epithelial cells, edema, and mild infiltration of the mast cells and lymphocytes. The SSU rDNA sequencing resulted in the sequencing of 1804 nucleotides that did not correspond to any myxosporean sequences deposited in GenBank. The closest phylogenetic affinity of the new species was to the South American Henneguya loreotoensis and Henneguya guanduensis, which also parasite the gills. The present study suggests this new myxosporean species has considerable pathogenic potential, and health monitoring should be implemented in A. lacustris fish farms to ensure production., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Purpose: Describe a new species of didymozoid digenean Neonematobothrium Yamaguti, 1965 from the operculum of the scombrid fish, Euthynnus alletteratus (Rafinesque, 1810), in the Southwest Atlantic Ocean off Brazil., Methods: Thirty-four specimens of E. alletteratus were collected in the coastal zone of the state of Rio de Janeiro and obtained from local fishermen between 2006 and 2018 in the municipal market of São Pedro in Niterói, Brazil. The parasites were fixed in AFA (93% ethanol 70%, 5% formaldehyde, 2% glacial acetic acid) without pressure, stained with Langeron alcoholic acid carmine, dehydrated in an alcohol series, cleared in beachwood creosote or clove oil and mounted in Canada balsam as permanent slides., Results: Neonematobothrium annakohnae n. sp. is a member of the genus based on a combination of the following characteristics: body free, uncapsulated; body long and dorsoventrally flattened; esophagus surrounded by gland cells; ovary and vitellarium single, long, narrow and unbranched in the anterior and posterior halves of the body, respectively; uterus with three loops; and site of infection in subcutaneous tissue of scombrid fish. The new species differs from the two recognized species of the genus mainly by the size of the body, which is much larger, the shape of the genital pore, which is differentiated in a structure similar to a small sucker and by esophagus without diverticula., Conclusions: Neonematobothrium annakohnae n. sp. parasite of E. alletteratus from the Southwest Atlantic Ocean, described herein, represents the third species of Didymozoidae belonging to the genus Neonematobothrium. The two known species Neonematobothrium kawakawa Yamaguti, 1965 and Neonematobothrium dorsale Yamaguti, 1970 were described from fish belonging to the same genus of the host from Pacific Ocean. The diagnosis of the genus is enlarged to "esophagus with or without diverticula", to fill the characteristics presented by the new species. The description of N. annakohnae n. sp. demonstrates the need to expand the studies of these interesting and intriguing group of parasites, due to the fact that number of known didymozoids taxa in the Atlantic Ocean is far from representing the real situation., (© 2021. Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

Centrocestus formosanus is a digenean parasite first described from Asia, which parasitizes Melanoides tuberculata (Gastropoda: Thiaridae) at the first intermediate stage, and different fish species as second intermediate host. C. formosanus was previously recorded in Brazilian states, but never before in the southern region of this country. Recording and identification of digenean species through morphological identification is a taxonomic challenge. In light of this, we use an integrative taxonomic approach to report the occurrence of cercariae and metacercariae of C. formosanus in molluscs and fish, respectively, in an urban park located in southern Brazil. Specimens of M. tuberculata and the fishes Poecilia reticulata and Xiphophorus sp. (Poeciliidae) were collected for screening for parasites and molecular analyses using partial fragments of the 28S rDNA gene. The identification of C. formosanus obtained from molluscs and fish specimens permitted us to partially solve the life cycle of this parasite for the first time in the studied environment, demonstrating the necessity of monitoring and controlling molluscs populations. Nevertheless, our results will support future studies aiming to elucidate the life-cycle of C. formosanus in this region, since all sampled hosts' species are invasive in this environment.

The aim of this study was to compare the diversity and community structure of metazoan parasites in sympatric populations of Triportheus angulatus and Triportheus auritus in the Jari River basin, in the eastern Brazilian Amazon. All the specimens of T. angulatus and T. auritus examined were infected by Anacanthorus furculus, Anacanthorus pithophallus, Digenea gen. sp., Procamallanus (Spirocamallanus) inopinatus, Rhabdochona acuminata, Contracaecum sp., Ergasilus sp. and Acarina gen. sp. These parasites displayed aggregated or random dispersion. The parasite community in T. angulatus and T. auritus presented a similarity of 78%. The diversity indice and richness of parasite species were greater in T. auritus and there were differences in levels of host parasite infection for some infracommunities. Phyllodistomum spatula occurred only in T. angulatus, while metacercariae of Clinostomum marginatum and Digenea gen. sp.2 occurred only in T. auritus. The species richness of the parasites was influenced by host size, as well as the abundance of some parasite infracommunities. This is the first report of these parasites for T. angulatus and T. auritus, except for P. (S.) inopinatus and Contracaecum sp. for T. angulatus.

Infections caused by Edwardsiella ictaluri are one of the biggest problems in the catfish industry in North America and have been reported in fishes around the world. E. ictaluri was detected in juvenile pintado Pseudoplatystoma corruscans-a Brazilian catfish-in a farm in Paraná State, Brazil; diseased animals showed ascites and neurological signs of infection, with more than 50% mortality. Exotic invasive species susceptible to this bacterium have been reported in this area. We assessed the susceptibility of pintado to E. ictaluri with experimental infection via intraperitoneal and immersion methods as well as a cohabitation experiment with Nile tilapia Oreochromis niloticus and African walking catfish Clarias gariepinus, 2 exotic invasive species. All pintados challenged by intraperitoneal and immersion routes and those cohabiting with infected C. gariepinus died within 17 d of the challenge. Mortality of Nile tilapia reached 71.42% after the intraperitoneal and 35.71% in the immersion challenges within 28 d, whereas African walking catfish showed zero mortality. Observed clinical signs were comparable to those in the farm and those described in the literature as enteric septicemia of catfish. With this study, we demonstrated the susceptibility of P. corruscans to E. ictaluri, as well as interspecies transmission of this bacterium.

The present study describes a new species of the genus Sphaerospora found in the urinary bladder of the flag cichlid, Mesonauta festivus collected in Corre Água district of the municipality of Macapá, Amapá State (Brazil). The study includes morphological and phylogenetic analyses of the new parasite, to determine the relationship of the new species with related myxosporean species. The new species has polysporous plasmodia, which vary in size and shape. The mature myxospores are subspherical shape in valvar view. In the sutural view, the myxospores are 5.3±0.2 (5.2-5.6) μm in length and 7.0±0.7 (6.3-7.7) μm in width, with two piriform polar capsules equal size, 2.5±0.2 (2.3-2.8) μm in length and 1.8±0.2 (1.6-2.0) μm in width. The phylogenetic analyses of a partial sequence of the 18S rRNA gene confirmed the status of the new species and determined the relationship of the new species and related myxosporean species.The sum of the evidence indicates that, Sphaerospora festivus n. sp. belongs to the family Sphaerosporidae, and is the first record of the genus Sphaerospora from Brazil.

This study evaluated the presence of metazoan parasites in Leporinus macrocephalus from four fish farms from the western Amazon (Brazil). In 160 fish examined, prevalence was 61.9%, and parasites found were: Urocleidoides paradoxus, Urocleidoides eremitus, Tereancistrum parvus, Jainus leporini, Procamallanus (Spirocamallanus) inopinatus, Rhabdochona (Rhabdochona) acuminata, Dolops discoidalis and Ergasilus sp., but U. paradoxus was the dominant parasite. Jainus leporini and Ergasilus sp. occurred only in L. macrocephalus from one fish farm, while U. paradoxus, U. eremitus and T. parvus were found in fish from three fish farms. Dolops discoidalis, P. (S.) inopinatus and R. (R.) acuminata occurred only in L. macrocephalus from two fish farms. Higher infection levels were caused by U. paradoxus, U. eremitus and P. (S.) inopinatus, which had an aggregated dispersion. There was positive correlation between abundance of parasites and the length of hosts. No difference in the condition factor of parasitized and non-parasitized fish were found. Such differences between fish farms were attributed to differences in management and quality of cultivation environments, and data indicate the need to adopt prophylactic measures in the fish farms to prevent diseases in the future. This was the first report of D. discoidalis and Ergasilus sp. for L. macrocephalus.

In the freshwater ecosystems of Brazil can be found high biodiversity of fish, about 5160 species. However, the Jacaré-Pepira River, located in the state of São Paulo, Brazil, presents a diversity of fish still to be explored in ichthyological studies. Metazoan parasites of Pimelodus maculatus and Rhamdia quelen were qualitatively and quantitatively diagnosed. Ten species of parasites (Demidospermus sp., D. majusculus, D. bidiverticulatum, D. paravalenciennesi, Ameloblastella paranaensis, Scleroductus sp., Riggia sp., Austrodiplostomum compactum, Helobdella sp. and Neochinorhynchus pimelodi) were collected in P. maculatus and eight species of parasites (Aphanoblastella robustus, A. mastigatus, Phyllodistomum rhamdiae, Crocodilicola pseudostoma, Henneguya jundiai, Contracaecum sp., Rhabdochona sp. and Capillariidae gen. sp.) were collected in R. quelen. All parasites presented aggregate distribution. A significant correlation was observed in P. maculatus concerning the weight with the prevalence of ectoparasite D. majusculus; however, R. quelen showed a relation to the length and weight with the abundance of ectoparasite A. mastigatus and endoparasites. The parasitic community of P. maculatus and R. quelen was characterized by high diversity, high richness, and low uniformity.

Myxosporidiosis is an infectious disease caused by myxozoans of the Phylum Cnidaria, Class Myxosporea, and Order Bivalvulida, considered a common parasite in fresh and saltwater fishes that parasitize many organs, especially gills. In the present study, 49 specimens of fishes belonging to eight genera: Tetragonopterus, Leporinus, Myleus, Pirinampus, Rhapiodon, Pygocentrus, Ageneiosus, and Serrasalmus were collected and blood smears were made, fixed with absolute methanol, and stained with Giemsa 10% to survey hemoparasites. However, myxospores were found in the circulating blood of five (10.20%) fishes belonging to genus Tetragonopterus, Myleus, and Pygocentrus. Two morphological types of Myxobolus spp. were identified in all the five fish specimens analyzed. Usually, investigations on myxozoans in fish are carried out with the search for plasmodia or cysts in the fish organs and observation of the cavity of organs. Nevertheless, this study highlights the importance of also examining the blood of these animals, since these parasites can cause severe pathogenic diseases in fish. Thus, the blood analyses can proportionate preventive sanitary control for commercial fish avoiding economic loss.

This article discusses a study which examined copepod parasites of Curimatella lepidura from the Três Marias Reservoir in Brazil. The study recorded the biometric data, gender and collection site on necropsy forms. It applied the procedures for collection, fixation, conservation and mounting the copepods on slides for identification according to Thatcher. Using the Mann-Whitney U-test with normal approximation, the study also evaluated the possible influence of host gender on the parasite abundance and intensity.

Hoplias malabaricus is a non-migratory fish commonly found in the Mogi Guaçu River basin, mainly feeding on fish, small crustaceans and insects. It forms part of the diet for humans, birds and some mammals. This fish has great nutritional value, with both good quality and good quantities of essential vitamins and amino acids. Regarding parasitic fauna, this fish can host different species of helminths in its gastrointestinal tract. The aim of the present study was to investigate the possible interference of parasitism in the meat yield from H. malabaricus and the centesimal composition. For this purpose, fish specimens were collected from marginal lagoons of the Mogi Guaçu River (Pirassununga, state of São Paulo, Brazil) using hooks and fishing nets. We found that all specimens of H. malabaricus were parasitized by at least one species, including larvae of Contracaecum sp. (Nematoda: Anisakidae). Parasitism did not have any significant influence on centesimal composition, but meat yield was negatively correlated with the abundance of larvae.

Calyptospora species are coccids that commonly cause liver infections in fish all around the world. This paper describes the morphology and histopathological characteristics of liver infection caused by Calyptospora sp. in black piranha Serrasalmus rhombeus, from the Capim River, in the municipality of Ipixuna do Pará, state of Pará (Brazil). Specimens were collected, analyzed and necropsied and tissue fragments containing parasites were prepared for histology and scanning electron microscopy. Parasitism was detected in 33.0% of the analyzed specimens, which had spherical oocysts in the liver, with four pyriform sporocysts presenting sporozoites internally. A histological examination revealed oocysts positioned close to blood vessels, causing necrosis and degeneration of hepatic parenchyma, while the presence of mononuclear cell infiltrate and melanomacrophages indicated the onset of an inflammatory process. This is the first record of the genus Calyptospora in fish from the Capim River.

The farming of Colossoma macropomum has intensified in recent years, leading to an increased need for research into the health of the fish. We therefore investigated the diversity of myxosporeans (Cnidaria: Myxozoa) infecting C. macropomum in a breeding system in the municipality of Rio Branco, in the state of Acre, Brazil. Twenty-four fish specimens were examined from June to August 2018. Our results revealed a high prevalence of infection, with 23 specimens (95.8%) exhibiting myxosporean plasmodia. Morphological analysis, based on light and electron microscopies, and molecular analysis (small subunit ribosomal DNA [SSU rDNA] sequencing) revealed the occurrence of three novel species of the genus Myxobolus. Plasmodia of Myxobolus guttae n. sp. were found in the fins of 75% of the specimens, and the myxospores were pear-shaped, measuring 12.3 ± 0.6 (10.3-13.5) μm in length, 8.1 ± 0.3 (7.1-8.6) μm in width, and 5.1 ± 0.6 (4.5-6.5) μm in thickness. The polar capsules were elongated and equal in size, measuring 6.8 ± 0.5 (5.8-7.6) μm in length and 2.5 ± 0.3 (1.8-3.1) μm in width, exhibiting polar tubules with 9-10 coils. The plasmodia of Myxobolus longus n. sp. were found in the gills of 45.8% of the C. macropomum specimens, and the myxospores were fusiform, measuring 16.4 ± 0.6 (14.7-17.3) μm in length, 7.1 ± 0.2 (6.8-7.7) μm in width and 5.5 ± 0.6 (4.4-6.6) μm in thickness. The polar capsules occupied more than half of the myxospore, exhibiting different sizes, the largest measuring 9.2 ± 0.5 (7.3-10.1) μm in length and 2.5 ± 0.3 (2.0-3.1) μm in width, while the smallest measured 8.5 ± 0.4 (7.1-9.1) μm in length and 2.4 ± 0.2 (1.9-3.0) μm in width. Both polar capsules contained polar tubules with 10-12 coils. For Myxobolus tambaquiensis n. sp., plasmodia were found in the opercular cavity of 41.7% of the fish specimens, and the myxospores had an oval shape, measuring 10.0 ± 0.4 (9.5-11.3) μm in length, 6.5 ± 0.2 (6.1-7.1) μm in width, and 4.6 ± 0.4 (3.9-5.6) μm in thickness. The polar capsules were elongated and equal in size, measuring 4.9 ± 0.2 (4.4-5.3) μm in length and 1.9 ± 0.2 (1.5-2.2) μm in width, closing with 8-9 coils of the polar tubule. The morphological and sequencing data of the SSU rDNA showed that the three species studied herein remain unknown to science, increasing the diversity of myxosporeans infecting C. macropomum, an iconic fish in South American freshwater fish farming. The SSU rDNA based phylogenetic analysis revealed that Myxobolus spp. parasites of C. macropomum did not have a monophyletic origin, identifying different times and pathways of the acquisition of parasites by this host species., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Bacterial diseases are common in ornamental fish, more frequently associated with ubiquitous bacteria from the aquarium environment. The disease can lead to fish mortality and cause high economic losses if not rapidly controlled. The aim of this study was to identify the main causative bacterial agents of infection in ornamental fish with different clinical signs. A total of 126 freshwater fish, from 12 families and 38 species, with clinical signs were collected in a wholesaler in São Paulo, SP, Brazil. Samples were taken from the eye, skin ulcers, kidneys, and gills, plated on MacConkey, CHROMagar Orientation, and blood agar and incubated under aerobic and anaerobic conditions. Bacterial identification was performed by MALDI-TOF mass spectrometry. From the 126 studied animals, 112 were positive for bacterial isolation. Among the positive animals, 32.1% presented infection caused by a single bacterial species, while in the remaining 67.9%, two to six different bacterial species were identified. A total of 259 bacterial strains were obtained and classified among 46 bacterial species. The species of higher frequency were Aeromonas veronii (26.3%), Aeromonas hydrophilla (16.2%), Shewanella putrefaciens (7.3%), Citrobacter freundii (8.1%), Vibrio albensis (5.8%), and Klebsiella pneumoniae (4.2%). MALDI-TOF MS showed to be a rapid method for diagnosis of bacterial disease outbreaks in ornamental fish establishments.

A total of 30 specimens of the Amazonian electric knifefish, Brachyhypopomus beebei Schultz, 1944 (Gymnotiformes: Hypopomidae), were collected from the Peixe-Boi River in the state of Pará, Brazil (1°06'59" S; 47°18'26" W). Fragments of the brain tissue were extracted for analysis via optical microscopy, and 18 specimens (60%) presented microparasites of the genus Myxobolus, with unequal capsules. The spores were 18.6 µm (17.7-19.8 µm) long and 8.6 µm (8.4-9.0 µm) wide; the largest polar capsule was 13.0 µm (12.4-13.4 µm) long and 5.6 µm (5.3-6.0 µm) wide, and the smallest capsule was 5.0 µm (4.5-5.3 µm) long and 2.5 µm (2.3-2.6 µm) wide. Infected brain fragments were extracted for histological processing and staining with hematoxylin-eosin and Ziehl-Neelsen. Some fragments were conserved in ethanol for molecular genetics analysis. A partial sequence of the 18S DNA gene was obtained from the spores, which did not correspond to any other sequences deposited in GenBank, although it did form a clade with other Myxobolus parasites of the nervous system. The morphological data, together with molecular phylogeny, supported the designation of a new species Myxobolus freitasi n. sp.

This study aimed to investigate the presence of nematodes Spirocamallanus krameri and Contracaecum sp. in Hoplerythrinus unitaeniatus caught in a lake in the state of Pará, in northern Brazil, eastern Amazon region (Brazil). From 92 hosts, 83.7% were infected, and a total of 401 parasites were covered. There was a high prevalence of S. krameri, while the predominance was of Contracaecum sp. larvae. Both parasite species presented aggregated dispersion, and abundance of these parasites presented positive correlation with weight and length of the hosts. Morphological and morphometric data of third-stage larvae of Contracaecum sp. are described.

A new cnidarian myxosporean infecting the spleen of an economic and ecological important bryconid fish (Salminus franciscanus) is described based on integrative taxonomic approach including morphological, ultrastructural, biological traits, geography, molecular data and phylogenetic analysis. In a total of thirty specimens examined, nineteen (63.3%) were infected by an undescribed parasite species belonging to the genus Myxobolus. Plasmodial development was asynchronous, with young development in the periphery and mature myxospores in the central area and without projections and microvilli in the plasmodial wall. Mature myxospores were ovoid in shape and measured 7.9 ± 0.2 μm (7.6-8.1 μm) in length and 5.4 ± 0.1 μm (5.0-5.6 μm) in width. The two polar capsules were equal in size, occupying a little more than half of the myxospore body, measuring 4.0 ± 0.2 μm (3.9-4.1 μm) in length and 1.7 ± 0.1 μm (1.5-1.8 μm) in width. The polar tubules coiled in six turns, perpendicular to the long axis of polar capsule. Phylogenetic analysis placed the new species within a clade containing nine myxobolid species from South American characiforms fish and appears as a close species of Myxobolus pantanalis. Nevertheless, the sequences of the new species and M. pantanalis have a large genetic divergence of 13.5% in their SSU rDNA. In light of the differences observed from the integrative taxonomy, we confidently considered that this isolate is a new species of cnidarian myxosporean, M. douradae n. sp., increasing the knowledge of diversity of this enigmatic group of cnidarians., (Copyright © 2020 Elsevier Ltd. All rights reserved.)