Occurrence of diseases in fish used for experimental research.

The objective of the present study was to evaluate the occurrence of pathogens and diseases in laboratory fish over a 10-year period at the Centre for Experimental Fish Pathology of Sicily, University of Messina. This report also emphasizes the adverse effects of subclinical infections on research endpoints, as well as the importance of animal health with respect to welfare. Infections in fish used for research can alter experimental outcomes, increase the variability of data, and impede experimental reproducibility. For this purpose, 411 diseased fish of different species (out of a total of 2820 fish) that belonged to four marine species (Dicentrarchus labrax, Sparus aurata, Argyrosomus regius and Mugil cephalus) and to four fresh water species (Danio rerio, Carassius auratus, Xiphophorus variatus and Poecilia reticulata) were examined in this study. Our results showed that mycobacteriosis and myxosporidiosis were the most important diseases found in our research fish, and the results represent a useful tool to obtain wider knowledge on the incidence of various diseases in different fish species. Further studies in this field are necessary to improve knowledge on the state of the health of fish used for research.

Differentiation of Flavobacterium psychrophilum from Flavobacterium psychrophilum-like species by MALDI-TOF mass spectrometry.

Rainbow trout fry syndrome (RTFS) is an important infectious disease caused by Flavobacterium psychrophilum affecting farmed salmonids worldwide. Other Flavobacterium psychrophilum-like species (F. plurextorum, F. oncorhynchi, F. tructae, F. collinsii and F. piscis) have been isolated from diseased rainbow trout fry suspected of RTFS although the epidemiological and clinical relevance of these pathogens are unknown. The objective of this study was to evaluate the potential use of MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization-Time of Flight) Mass Spectrometry as method for specific identification of F. psychrophilum and its differentiation from other F. psychrophilum-like species isolated from diseased fish. Fifty-three isolates were analyzed after the creation of the Main Spectrum Profile (MSP) of reference strains of each of abovementioned species. F. psychrophilum exhibited a mass spectra very different from those of F. psychrophilum-like species, with five peaks (m/z 3654, 4585, 5388, 6730 and 7310) present only in F. psychrophilum isolates, and three peaks (m/z 6170, 7098 and 9241) absent in F. psychrophilum but present in all F. psychrophilum-like species. All F. psychrophilum isolates were correctly identified and differentiated from the F. psychrophilum-like species by MALDI-TOF. Although this approach showed a limited ability to differentiate among F. psychrophilum-like species, its complementation with a few simple biochemical tests may represent an alternative approach for the routine identification of the Flavobacterium psychrophilum-like species.

A novel use of social media to evaluate the occurrence of skin lesions affecting wild dusky grouper, Epinephelus marginatus (Lowe, 1834), in Libyan coastal waters.

The social media network Facebook™ was used to gather information on the occurrence and geographical distribution of dusky grouper dermatitis, a skin lesion affecting the dusky grouper, Epinephelus marginatus. Dusky grouper are common targets for spear fishermen in the Mediterranean and by monitoring spearfishing activity in Libyan waters, it was possible to document skin lesions from their entries on Facebook. Thirty-two Facebook accounts and 8 Facebook groups posting from 23 Libyan coastal cities provided a retrospective observational data set comprising a total of 382 images of dusky grouper caught by spearfishing between December 2011 and December 2015. Skin lesions were observable on 57/362 fish, for which images were of sufficient quality for analysis, giving a minimal prevalence for lesions of 15.75%. Only dusky grouper exceeding an estimated 40 cm total length exhibited lesions. The ability to collect useful data about the occurrence and geographical distribution of pathological conditions affecting wild fish using social media networks demonstrates their potential utility as a tool to support epidemiological studies and monitor the health of populations of aquatic animals. To our knowledge, this represents the first time that such an approach has been applied for assessing health in a wild population of fish.

Frequency and histologic characterization of coelomatic neoplasms in koi Cyprinus carpio koi.

Koi carp presenting with coelomatic neoplastic lesions are of growing importance in Switzerland and elsewhere in Europe, as clinical diagnosis is usually difficult and prognosis is usually poor because of late recognition. To gain more information about this condition, between 2008 and 2012, 117 koi diagnosed with coelomatic tumours were included in this study. The nature and growth characteristics of these pathologic tissues were documented. Out of 117 koi, 48.9% (n = 57) were female; the ovary was the most often affected organ (35%, n = 41), and in 62.4% (n =73) of cases, the cells of origin were identified as stromal cells of the sex-cord and the tumours were identified as sex-cord stromal tumours. The characteristics of growth and histology showed that the majority of tumours were malignant.

Histopathological alterations of the heart in fish: proposal for a standardized assessment.

Histopathological alterations in the heart are often reported in fish as a result of exposure to a variety of chemical compounds. However, researchers presently lack a standardized method for the evaluation of histopathological alterations in the cardiovascular system of fish and the calculation of an 'organ index'. Therefore, we designed a method for a standardized assessment and evaluation of histopathological alterations in the heart of fish. As a model species, we used rainbow trout Oncorhynchus mykiss, but the protocol was also successfully applied to other fish species belonging to different taxonomic orders. To test the protocol, we re-evaluated sections of atenolol-exposed and unexposed rainbow trout obtained in a previous study. The results were in accordance with those previously published, demonstrating the applicability of the protocol. The protocol provides a universal method for the comparative evaluation of histopathological changes in the heart of fish.

New host record of five Flavobacterium species associated with tropical fresh water farmed fishes from North India

Abstract Yellow pigmented, filamentous, Gram-negative bacteria belonging to genus Flavobacterium are commonly associated with infections in stressed fish. In this study, inter-species diversity of Flavobacterium was studied in apparently healthy freshwater farmed fishes. For this, ninety one yellow pigmented bacteria were isolated from skin and gill samples (n = 38) of three farmed fish species i.e. Labeo rohita, Catla catla and Cyprinus carpio. Among them, only twelve bacterial isolates (13.18%) were identified as Flavobacterium spp. on the basis of morphological, biochemical tests, partial 16S rDNA gene sequencing and phylogenetic analysis. On the basis of 16S rDNA gene sequencing, all the 12 isolates were 97.6-100% similar to six different formally described species of genus Flavobacterium. The 16S rDNA based phylogenetic analysis grouped these strains into six different clades. Of the 12 isolates, six strains (Fl9S1-6) grouped with F. suncheonense, two strains (Fl6I2, Fl6I3) with F. indicum and the rest four strains (Fl1A1, Fl2G1, Fl3H1 and Fl10T1) clustered with F. aquaticum, F. granuli, F. hercynium and F. terrae, respectively. None of these species except, F. hercynium were previously reported from fish. All the isolated Flavobacterium species possessed the ability of adhesion and biofilm formation to colonize the external surface of healthy fish. The present study is the first record of tropical freshwater farmed fishes as hosts to five environmentally associated species of the Flavobacterium.

A retrospective study of the prevalence and classification of intestinal neoplasia in zebrafish (Danio rerio).

For over a decade, spontaneous intestinal neoplasia has been observed in zebrafish (Danio rerio) submitted to the ZIRC (Zebrafish International Resource Center) diagnostic service. In addition, zebrafish displayed preneoplastic intestinal changes including hyperplasia, dysplasia, and enteritis. A total of 195 zebrafish, representing 2% of the total fish submitted to the service, were diagnosed with these lesions. Neoplastic changes were classified either as adenocarcinoma or small cell carcinoma, with a few exceptions (carcinoma not otherwise specified, tubular adenoma, and tubulovillous adenoma). Tumor prevalence appeared similarly distributed between sexes and generally occurred in zebrafish greater than 1 year of age, although neoplastic changes were observed in fish 6 months of age. Eleven lines displayed these preneoplastic and neoplastic changes, including wild-types and mutants. Affected zebrafish originated from 18 facilities, but the majority of fish were from a single zebrafish research facility (hereafter referred to as the primary facility) that has submitted numerous samples to the ZIRC diagnostic service. Zebrafish from the primary facility submitted as normal sentinel fish demonstrate that these lesions are most often subclinical. Fish fed the diet from the primary facility and held at another location did not develop intestinal lesions, indicating that diet is not the etiologic agent.

[Two new species of Myxidium (Myxosporea: Myxidiidae) parasites of fresh water fish in Cameroon]. / Deux espèces nouvelles de Myxidium (Myxosporea: Myxidiidae) parasites de poissons d'eau douce du Cameroun.

The study of Myxosporidia infecting Clarias pachynema Boulenger, 1903 (Clariidae), Ctenopoma petherici Günther, 1864 (Anabantidae) and Parachanna obscura (Günther, 1861) (Channidae) from the basin of Nkam in Cameroon, revealed the presence of two new species of Myxosporidia of the genus Myxidium Bütschli, 1882, all found in the gall bladder of their hosts. These new species were: Myxidium nkamensis n. sp., found in Clarias pachynema and M. sangei n. sp. found in the gall bladder wall of Parachanna obscura. Two other species, Myxidium petrocephali Fomena and Bouix, 1986 and M. distichodi Kostoïngué, Faye and Toguebaye, 1998 were found in new hosts. The list of Myxidium species parasitizing African fresh water fishes is given.

The evolving story of Mycobacterium tuberculosis clade members detected in fish.

Advances in molecular analyses have permitted documentation of an increasing spectrum of mycobacteria infecting fish. Although some of these mycobacteria are not closely related, several species belong to the Mycobacterium tuberculosis clade. One member of the clade, M. marinum, is well known as an agent of piscine mycobacteriosis. Three other clade species, M. shottsii, M. pseudoshottsii and M. 'chesapeaki', have recently been identified as predominant disease agents in a widespread, continuing epizootic in wild striped bass of the Chesapeake Bay. A fifth clade member, M. ulcerans, has recently been indirectly detected in wild, African cichlid fish. As M. ulcerans is the third most common human mycobacterial infection worldwide, even such indirect evidence of M. ulcerans in fish must be more thoroughly investigated. Complicating the differentiation of these clade members is the growing recognition of intraspecies and interspecies variation in phenotypes, genes and virulence. Thus, researchers must be aware of the variety of piscine isolates within the M. tuberculosis clade. This review summarizes the methods of detection and differentiation for this important group of mycobacteria.

Kudoa alliaria in flesh of Argentinian hoki Macruronus magellanicus (Gadiformes; Merlucciidae).

Myxozoans of the genus Kudoa are widespread parasites of marine fishes and primarily infect the body musculature of their hosts. Although Kudoa species are not usually associated with host mortality, some do form macroscopic cysts in the tissue and some are associated with post mortem tissue degradation. This is of concern to commercial fisheries as fillets may be unmarketable due to these infections. Because different species of Kudoa have different effects on their hosts, it is important to correctly identify species with epidemiological relevance, distinguishing those that are benign from those that are associated with these detrimental effects. Using morphological and molecular analyses, we identified K. alliaria infecting Argentinian hoki Macruronus magellanicus. Comparisons of the small subunit ribosomal DNA sequence revealed that K. alliaria is genetically very similar to K. rosenbuschi. Furthermore, there is significant overlap in myxospore dimensions between descriptions of these 2 Kudoa species as well as those of other Patagonian fishes. Thus, without careful examination of the myxospore dimensions, it may be difficult to identify these species on a routine basis. It is critical to accurately identify K. alliaria as, unlike K. rosenbuschi, it is not associated with tissue degradation. Ambiguities in some species descriptions highlight the need for thorough morphological analyses accompanied by molecular comparisons to clarify the species boundaries between Kudoa parasites of Patagonian fishes.

Highlighting ontogenetic shifts in habitat use by nocturnal coral reef fish.

The lagoon of Moorea Island was characterised by 12 distinct reef zones. Visual censuses allowed us to document the spatial distributions of recently settled juveniles vs adults of 17 nocturnal fish species among the 12 reef zones. Five distinct patterns in habitat use were found: an increase in the number of reef zones used during the adult stage (four species); a decrease in the number of reef zones adults used compared to recently settled juveniles (two species); the use of different reef zones (one species); the use of same reef zones but with relative densities different (one species); and no change in habitat use (nine species). Overall, this study is the first to explore the use of space by a broad range of nocturnal fish taxa to document the patterns and determinism of habitat shifts between juvenile and adult life stages.

Endoparasite communities of five fish species (Labridae: Cheilininae) from Lizard Island: how important is the ecology and phylogeny of the hosts?

The parasite community of animals is generally influenced by host physiology, ecology, and phylogeny. Therefore, sympatric and phylogenetically related hosts with similar ecologies should have similar parasite communities. To test this hypothesis we surveyed the endoparasites of 5 closely related cheilinine fishes (Labridae) from the Great Barrier Reef. They were Cheilinus chlorourus, C. trilobatus, C. fasciatus, Epibulus insidiator and Oxycheilinus diagramma. We examined the relationship between parasitological variables (richness, abundance and diversity) and host characteristics (body weight, diet and phylogeny). The 5 fishes had 31 parasite species with 9-18 parasite species per fish species. Cestode larvae (mostly Tetraphyllidea) were the most abundant and prevalent parasites followed by nematodes and digeneans. Parasites, body size and diet of hosts differed between fish species. In general, body weight, diet and host phylogeny each explained some of the variation in richness and composition of parasites among the fishes. The 2 most closely related species, Cheilinus chlorourus and C. trilobatus, had broadly similar parasites but the other fish species differed significantly in all variables. However, there was no all-encompassing pattern. This may be because different lineages of parasites may react differently to ecological variables. We also argue that adult parasites may respond principally to host diet. In contrast, larval parasite composition may respond both to host diet and predator-prey interactions because this is the path by which many parasites complete their life-cycles. Finally, variation in parasite phylogeny and parasite life-cycles among hosts likely increase the complexity of the system making it difficult to find all-encompassing patterns between host characteristics and parasites, particularly when all the species in rich parasite communities are considered.

Emerging pathologies in aquaculture: effects on production and food safety.

Infectious diseases represent a limiting factor for the further development of Italian aquaculture. The recent introduction and spreading of new pathogens, along with the global climatic change, has contributed to a considerable decrease in trout production. Emerging pathologies in rainbow trout culture include viral diseases, e.g. infectious haematopoietic necrosis (IHN), bacterial diseases, such as lactococcosis and visceral flavobacteriosis, and parasitical diseases, e.g. proliferative kidney disease (PKD). Higher mortality rates in trout fry and fingerlings are generally induced by visceral flavobacteriosis and IHN, while the main losses in large trout during the warm season are due to lactococcosis and PKD. Mariculture has at present a better sanitary status compared to trout culture, but a rapid dissemination of pathogens, including zoonosis agents, is envisaged also for seabass and seabream. Emerging pathologies in sea bass include VNN, pseudotuberculosis, streptococcosis and tuberculosis. Seabream is much more resistant and is mainly affected by novel Vibrio infections and enteromyxidiosis. A good sanitary management of fish farms is essential for avoiding or limiting losses caused by emerging pathologies. Transmission of zoonosis agents to man, through the consumption of cultured fish, is very remote in Italy. On the contrary, transmission of Streptococcus iniae, Vibrio vulnificus and Mycobacterium marinum by means of improper manipulation of infected fish, could represent a potential hazard for fish farmers and fish processors, as well as for people preparing fish meals.

Population dynamics of sealworm, Pseudoterranova decipienssensu lato, in sculpins, Myoxocephalus scorpius, from two areas in Norway between 1990 and 1996.

The abundance of sealworms (Pseudoterranova decipienss.l.) in sculpins (Myoxocephalus scorpius) was studied at Torbjørnskjaer, southeast Norway, and Vega, northern Norway, in samples from 1990 to 1996. The harbour seal ( Phoca vitulina) population at Torbjørnskjaer declined by 70% during the phocine distemper virus epizootic in 1988, and has increased during the 1990s. The abundance of sealworms in sculpins was relatively stable from 1992 to 1996 and any effect of the reduction in the number of harbour seals on the abundance of sealworms has been short-term. When correcting for size differences, young sculpins (2-4 years) from Torbjørnskjaer had higher abundances than those from Vega, while in old sculpins (5-7 years) the abundances seemed similar and stabilised. This happened at a younger age among the more heavily infected sculpins at Torbjørnskjaer than at Vega, and we interpret this as density dependence in the fish host.

Detection of a new Mycobacterium species in wild striped bass in the Chesapeake Bay.

Investigation into recent declines in striped bass health in the Chesapeake Bay in Maryland resulted in the isolation of a putative new species of Mycobacterium. This isolate was obtained from fish showing skin ulcers and internal granulomas in various organs. The isolate was slow growing at 28 degrees C; was nonchromogenic; showed no activities of nitrate reduction, catalase activity, Tween 80 hydrolysis, tellurite reduction, or arylsulfatase reduction; grew best at low salt concentrations; and was urease and pyrazinamidase positive. By PCR a unique insertional sequence was identified which matched nothing in any database. Analysis of the nearly complete 16S rRNA gene sequence also indicated a unique sequence which had 87.7% sequence homology to Mycobacterium ulcerans, 87.6% homology to Mycobacterium tuberculosis, and 85.9% homology to Mycobacterium marinum. Phylogenetic analysis placed the organism close to the tuberculosis complex. These data support the conclusion that the isolate probably represents a new mycobacterial species.

[Mycoses in fish]. / Mykosen bei Fischen.

Over 4 years 1.241 fish were examined mycologically. In 182 (14.7%) of them positive results were obtained. Most of the isolates belonged to the following genera: Cladosporium, Saprolegnia, Candida and Penicillium. Fungal infections were correlated with findings of Saprolegnia, Branchiomyces, Pythium, Ichtyophonus and sometimes Cladosporium. Most fungal isolates were etiologically irrelevant for diseases or death.

Overview of studies on liver carcinogenesis in English sole from Puget Sound; evidence for a xenobiotic chemical etiology. I: Pathology and epizootiology.

Livers of wild English sole (Parophrys vetulus) from polluted waterways and embayments of Puget Sound, Washington, are affected by a spectrum of multiple, co-occurring idiopathic hepatic lesions, including neoplasms, putative preneoplastic foci of cellular alteration, and unique degeneration conditions. Results from a statistical analysis of the patterns of co-occurrence of these lesions in wild English sole indicate that these lesions represent morphologically identifiable steps leading to the development of hepatic neoplasms. This sequence parallels the lesion progression in experimental models of chemically induced liver carcinogenesis in rodents. The hypothesis that these lesions in wild English sole can be caused by exposure to certain xenobiotic hepatotoxic and hepatocarcinogenic compounds in Puget Sound is based on: a) statistical associations between levels of aromatic hydrocarbons (sigma AHs) in sediment and prevalences of these idiopathic liver lesions, b) the contribution of sigma AHs in accounting for the variability in hepatic neoplasm prevalence in a logistic regression model, c) elevated odds ratios for several idiopathic hepatic lesion types in sole from polluted sites in Puget Sound, d) significant correlations between prevalences of idiopathic hepatic lesions and levels of fluorescent metabolites of aromatic compounds (FACs) in bile of English sole, and e) experimental induction of putatively preneoplastic focal lesions in English sole injected with a PAH-enriched fraction of an extract from a contaminated urban sediment from Puget Sound, that were morphologically identical to lesions found in wild English sole from the same site.