Parasitic crustaceans as a potential vector of MDR Vibrio alginolyticus infection among farmed marine fish in some earthen-pond based Egyptian aquaculture facilities: Molecular, epidemiological and pathological evidences.

Aquaculture is the fastest growing food-producing sector, accounting almost 50% of the world food fish demand. Considering the projected population growth over the next two decades, it is estimated that at least an additional 40 million tonnes of aquatic food will be required by 2030 to maintain the current per capita consumption (NACA/FAO, 2001). Marine aquaculture production was 30.2 million tonnes in 2004, representing 50.9% of the global aquaculture production (FAO, 2004). By major groupings, fish is the top group whether by quantity or by value at 47.4% and 53.9%, respectively. However, according to the World Aquaculture Society (WAS, 2006), the future of this sector must be based on the increase of scientific and technical developments, on sustainable practices, and, mainly, on the diversification of the cultured fish species. For this reason, the European Union has designed an innovative plan to increase the culture of new fish and shellfish species, mainly marine, maintaining the production of other consolidated species (UE, 2010). Marine fish farming is a very important activity of Spanish aquaculture industry. The main marine fish species intensively cultured are gilt-head seabream (Sparus aurata), European seabass (Dicentrarchus labrax), and turbot (Scophthalmus maximus), achieving production percentages of 47.91, 12.5 and 18.62%, respectively (MAPA, 2008). In last 7 years, several new marine fish species are being evaluated as potential candidates for aquaculture production. In Southern Spain, studies on the reproductive cycles, nutrition, growth, histology and immune system of species such as Senegelese sole (Solea senegalensis), redbanded seabream (Pagrus auriga), common seabream (Pagrus pagrus), white seabream (Diplodus sargus), and meagre (Argyrosomus regius) are ongoing (Cardenas & Calvo, 2003; Prieto et al., 2003; Ponce et al., 2004; Manchado et al., 2005; Fernandez-Trujillo et al., 2006; 2008; Martin-Antonio et al., 2007; Cardenas & Manchado, 2008). However, the intensive

Parasitic infestation is considered as serious problem in both wild and cultured fish and has great impacts on the growth, reproduction and survival of their hosts. In Egypt, marine aquaculture is in continuous development so the importance of parasitic infestation studies becomes more evident. The present study investigated the gill parasitic infestation in both wild and cultured Dicentrarcus labrax (Seabass) and Sparus aurata (Seabream ). A total of 236 samples of D. labrax (126 wild and 110 cultured) and 294 of S. aurata (150 wild and 144 cultured) were collected during 2016/2017 from different localities along Mediterranean sea (wild fish samples) and some private marine fish farms (cultured fish samples) in Egypt and examined for parasitic gill infestation. The isolated parasites were identified and the infestation rates of both wild fish species were compared with that of the cultured same species. Results revealed that out of the total examined (530) samples, 378 (71.32%) were found parasitized by monogenean and crustacean parasite species. The examined D. Labrax recorded a total infestation rate of 77.1% where Lernanthropus kroyeri , Caligus species (Copepoda) and Diplectenum aequans (Monogenean) were the most prevalent parasitic species, while Nerocila orbegnyi (isopod) and Furnestinia echeneis (monogenea) were the dominate species among S.aurata which recorded 66.7% as total infestation rate. The study also concluded that gill parasitic infestation rates among the examined wild samples of both fish species were found higher than those of the examined cultured ones. The infested S. labrax gills with Caligus spp. showed excessive mucus secretions and paleness in addition to the detected hyperplasia and necrosis of epithelial cells of primary gill filaments by histopathlogical examination.

The present study was conducted on a total of 200 marine fishes (100 of Dicentrarchus labrax and 100 of D.punctatus) collected from different private fish farms in Ismailia Governorate. There were no pathognomonic lesions in the naturally infested fishes except marbling appearance of gills infested by Isopoda. Skin lesions were found in opercular cavities of fishes infested by Isopoda. The main P.M lesions were hemorrhagic areas on EBS and emaciation. Some fishes showed Sea lice in the buccal cavity with ulcerative lesions in the area of attachment. The highest crustacean infestation rate was recorded in Dicentrarchus labrax (75%) followed by D.punctatus (42%). The isolated crustacean parasites from both fish species were copepods (Lernanthropus kroyeri, Caligus minimus and C.longipedis) and Isopods (Nerocila spp., Renocila spp. and Anilocra spp.).Total and Seasonal prevalence of crustacean parasites, histopathological picture and identification of copepod parasites using molecular biology (PCR) were also recorded.

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 58:1-8 (2004) - doi:10.3354/dao058001 Phenotypic characterization and description of two major O-serotypes in Tenacibaculum maritimum strains from marine fishes Ruben Avendaño-Herrera, Beatriz Magariños, Sonia López-Romalde, Jesús L. Romalde, Alicia E. Toranzo* Departamento de Microbiología y Parasitología, Facultad de Biología, Universidad de Santiago, 15782 Santiago de Compostela, Spain *E-mail: mpaetjlb@usc.es ABSTRACT: Tenacibaculum maritimum is the etiological agent of marine flexibacteriosis disease, with the potential to cause severe mortalities in various cultured marine fishes. The development of effective preventive measures (i.e. vaccination) requires biochemical, serological and genetic knowledge of the pathogen. With this aim, the biochemical and antigenic characteristics of T. maritimum strains isolated from sole, turbot and gilthead sea bream were analysed. Rabbit antisera were prepared against sole and turbot strains to examine the antigenic relationships between the 29 isolates and 3 reference strains. The results of the slide agglutination test, dot-blot assay and immunoblotting of lipopolysaccharides (LPS) and membrane proteins were evaluated. All bacteria studied were biochemically identical to the T. maritimum reference strains. The slide agglutination assays using O antigens revealed cross-reaction for all strains regardless of the host species and serum employed. However, when the dot-blot assays were performed, the existence of antigenic heterogeneity was demonstrated. This heterogeneity was supported by immunoblot analysis of the LPS, which clearly revealed 2 major serological groups that were distinguishable without the use of absorbed antiserum: Serotypes O1 and O2. These 2 serotypes seem to be host-specfic. In addition, 2 sole isolates and the Japanese reference strains displayed cross-reaction with both sera in all serological assays, and are considered to constitute a minor serotype, O1/O2. Analysis of total and outer membrane proteins revealed that all strains share a considerable number of common bands that are antigenically related. KEY WORDS: Tenacibaculum maritimum · O-antigen · Lipopolysaccharides · Serotype · Marine fishes Full article in pdf format NextCite this article as: Avendaño-Herrera R, Magariños B, López-Romalde S, Romalde JL, Toranzo AE (2004) Phenotypic characterization and description of two major O-serotypes in Tenacibaculum maritimum strains from marine fishes. Dis Aquat Org 58:1-8. https://doi.org/10.3354/dao058001Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 58, No. 1. Online publication date: January 28, 2004 Print ISSN: 0177-5103; Online ISSN: 1616-1580 Copyright © 2004 Inter-Research.

Piscine lactococcosis, caused by Lactococcus garvieae, has traditionally been reported in rainbow trout and marine fish in specific regions. However, its first outbreak in farmed gilthead seabream Sparus aurata in the northern Tyrrhenian Sea marks a significant expansion in the distribution of the disease. In 2024, a total of 212 gilthead seabream from three different aquaculture facilities, including one offshore farm with floating cages and two land-based tank farms, were subjected to diagnostic exams during mortality outbreaks. Bacterial isolation and molecular identification confirmed L. garvieae in market-size gilthead seabream collected during mortality outbreaks in the warm season or at seawater temperatures > 18°C. Our results highlight the importance of environmental monitoring and pathogen management in preventing piscine lactococcosis. The outbreaks align with previous studies on L. garvieae infections in marine fish, particularly regarding water temperature. The expanding geographic range of the pathogen necessitates further investigation into its ecology, particularly in Mediterranean aquaculture. This study highlights the need for improved biosecurity measures, early detection methods, and tailored vaccination strategies to mitigate the impact of piscine lactococcosis in gilthead seabream farming. Future research should focus on understanding the environmental triggers and host-pathogen interactions to develop more effective control strategies.

Ichthyophonus sp. is reported for the first time in Mugil capito (thinlip grey mullet) and Li a saliens (leaping grey mullet). The fungus was also found in L. aurata (golden grey mullet), Dicentrarchus labrax (sea bass), Sparus aurata (gilthead sea bream) and Scophthalmus maximus (turbot), whereas Mugil cephalus (grey mullet) was not parasitized. In fish sampled periodically, the highest prevalences were observed in sea bass and the lowest in turbot. Among the fish sampled occasionally, the fungus was found associated to an epizootic in thinlip grey mullet. Ichthyophonus was never found in fish weighing <0·5 g. An increase in the prevalence of infection with the age of turbot and gilthead sea bream was observed. Gilthead sea bream and sea bass showed higher prevalences in a closed system than in open and semi‐intensive systems. Multinucleate spherical spores, hyphae and endospores of Ichthyophonus sp. parasitized different organs of thinlip and leaping grey mullets, though infection intensity was maximal in the spleen. In the remaining fish, the fungus was found mainly in the trunk kidney, where it appeared frequently in a necrotic form. Ichthyophonus sp. can be considered a potential threat for marine fish aquaculture, especially in culture conditions which may favour the introduction and transmission of the fungus.

Marine fish plays an important role in the human diet with an observed increase in the consumption of marine fish. Thus, it is necessary to study the prevalence of pathogens in fish to ensure the safety of fish and fish products. A total of 100 random samples of marine water fish represented by Sardine (Sardina pilchardus), Barbone (Mullus surmuletus), Saurida undosquamis (Mackerel) and Sparus aurata (Denise) (25 of each) were collected from local markets in Alexandria Governorate. Samples were examined bacteriologically immediately after arrival to the laboratory for isolation and identification of Salmonella, Yersinia and Vibrio species. The obtained results revealed that incidence of Salmonella isolated from the examined samples of marine fish species was 16, 8, 4 and 8% in Sardine, Barboni, Mackerel and Dinese, respectively. Serotyping of Salmonella isolated from the examined samples of marine fish clarified the detection of S. Enteritidis, S. Typhimurium and S. Haifa. Also, it was found that the incidence of Yersinia isolated from the examined samples of marine fish species was 44, 36, 24 and 28 % in Sardine, Barboni, Mackerel and Dinese, respectively and the biochemical identification clarified the detection of Y. enterocolitica, Y. frederiksenii, Y. ruckeri and Y. intermedia. Finally, the incidence of Vibrio isolated from the examined samples of marine fish species was 36, 24, 20 and 16 % in Sardine, Barboni, Mackerel and Dinese, respectively and the biochemical identification of the obtained isolates of Vibrio clarified the presence of V. parahaemolyticus and V. cholera. On the basis of the previously mentioned results, Salmonella, Yersinia and Vibrio still constitute common contaminants of marine fish and its presence is very important due to its public health significance, good hygienic measures must be applied to obtain safe marine fish.

In contrast to numerous documented pathogens and infectious diseases of aquaculture, there is a lack of baseline data and information regarding pathogenic agents’ prevalence in wild marine fish populations. This study focused on two common fish pathogenic microorganisms, namely Mycobacterium species and Vibrio species, both of which are known to be major causes of fish loss, occasionally to the extent of being a limiting factor in fish production. Both microorganisms are known as zoonotic agents. In total, 210 wild marine indigenous and Lessepsian fish from four different species from the eastern Mediterranean Sea were sampled and tested for Vibrio species and Mycobacterium species during a two-year period (2016–2017). Using PCR with 16S rRNA primers, we detected different strain variations of Mycobacterium species and Vibrio species and, based on the sequencing results, the overall prevalence for Vibrio species in wild fish in 2016 was significantly higher compared to 2017. No significant difference was detected for Mycobacterium species prevalence in wild fish between 2016 and 2017. In addition, 72 gilthead seabream (Sparus aurata) from an Israeli offshore marine farm were also examined during the two-year period (2017–2018). The results suggest that Mycobacterium species prevalence was significantly higher in 2018, while in 2017 there was no positive results for Mycobacterium species. In addition, there was no significant difference between both years in regard to the prevalence of Vibrio species for maricultured fish. These results highlight the necessity of continuous molecular monitoring in order to evaluate the prevalence of pathogenic microorganisms in both wild and cultured fish populations.

Diversity of Marine Fish of India

Prevalence of listeria, Aeromonas, and Vibrio species in fish used for human consumption in Turkey.

World production of sea bream and sea bass farming has been rising over time. The total production of gilthead sea bream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax, L.) in Europe has been increased. These marine fish species have high economic value in the aquaculture industry. More specifically, the total production of 92,310 tonnes in 1999 amounted to 175,196 tonnes in 2006, representing an average annual growth rate of 9.6%. Greece is the country with the largest production of euryhaline fish (sea bream and sea bass) between Mediterranean countries. In 2008, Greece held its largest production (130,000 tonnes of which 95,000 tonnes sea bass and sea bream). Climatic and geomorphologic conditions of Greece promoting the cultivation of euryhaline fish, grants and projects given by the European Union, the decline of fish stocks and the restrictions have been imposed last yeas in fishing, contributed significantly in the development of the industry of fish farming. Today the industry fully covers the needs of the Greek market and most of the quantity is exported to foreign markets, the main destination countries Italy, Spain, France, England and Portugal. Currently, additional species have entered in the farming, belonging mainly to the family Sparidae, such as Puntazzo pntazzo, Diplodus sargus, Lithognathus mormyrus, Pagrus pagrus, Pagellus erythrinus and Dentex dentex. Bacterial diseases of fish origin have become one of the major agents of economical losses since the beginning of marine farming (Kubota & Takakuwa, 1963; Anderson & Conroy, 1970). The development of intensive marine fish farming in the form of the concentration of large quantities of biomass in a relatively small volume water leads-under certain conditions (combination of factors) – to the emergence of diseases which lead to losses in the population. The occurrence of a disease can lead to death or symptoms both refer to deviation from the normal structure or function of the host (Hedrick, 1998). Most diseases of farmed fish originate from wild populations. The close contact between farmed and wild fish results in exchange of pathogens. The clinical symptoms caused by any pathogen depend on the type of host, age of the fish and stage of disease (acute, chronic, subclinical form). Moreover, in some cases, there is no correlation between internal and external injuries. In fact, systemic diseases (eg. pasteurellosis) with high mortality rates, causing internal damage to infected fish, but often have a healthy appearance. Conversely, other diseases with relatively low mortality cause significant physical damage, including ulcers, necrosis, exophthalmos, making the fish unfit for the market.The diseases, the number and

Arthropoda parasites of fish are: Copepoda, Branchiura and Isopoda. The Branchiura are exclusively parasitic, while most of the Copepoda and Isopoda are free-living. About 450 species of isopods are parasites of marine and freshwater fish. Isopods are Malacostraca. In the isopod families Cymothoidae and Anilocridae, which number about 200 species, are parasitic species that remain on the fish body throughout their life. The main genus/species of interest to the Greek marine fish farmers is Ceratothoa oestroides. Other isopod species (Flabellifera-Cymothoidae, Anilocridae) have been reported to infest net-pen reared sea bass and/or sea bream, such as: Anilocra physodes, Nerocila orbignyi, Emetha audouini, Ceratothoa parallela. The name "Anilocra" is widely used by farmers for any type of isopods infesting their fish. A mature gravid female isopod releases about 400-550 larvae at a time. Ceratothoa sp are constantly fertile, remaining in reproductive condition throughout the year. Fecundity and hatching rate increase in warmer temperatures, July being the period of optimum isopod proliferation in the Mediterranean.Members of these families (Cymothoidae, Anilocridae) are protandrus hermaphrodites, i.e. an individual develops and functions first as a male and then may become a female. Sexual differentiation takes place after the pulii II larvae have left the marsupium. Regarding the most sensitive age of the fish hosts when the parasites attach in their buccal cavity, empirical observations agree with research results that there is a significant correlation between the level of infection and the length of the host. Fish fry are the evident target for isopod attachment. Ceratothoa oestroides pulii II larvae remain free swimming and capable of infecting a host for about 7 days at 22°C. During this period, in case the host dies, after successful settlement of the parasite, the isopod larvae immediately abandon the dead fish and are still capable of actively seeking another. Parasitic isopods are fairly common crustacean infestations of wild tropical marine fish.They are less common in cold marine waters and not often found on freshwater fish. The distribution of parasitic isopods, as that of all other parasites, is closely related to the occurrence and ecology of their hosts. Demersal fish in coastal waters are mainly infected, the parasites being rarer in benthic- and pelagic fish. Intensive fish farming in coastal waters in the Mediterranean provides an almost ideal environment for isopod parasites, hence, farmed sea bream (Sparus auratus), but mostly sea bass (Dicentrarchus labrax) infestations by isopods comprise a frequent problem in the Mediterranean. Ceratothoa oestroides is the most common among the isopod parasites and inflicts major damage to farmed fish. Among the wild fish, the usual hosts of parasitic isopods are mullets (Mugil sp., Liza sp.), bogues (Boops boops), goldlines (Boops salpa), striped breams (Lithognathus mormyrus) and white breams (Diplodus sargus). These fish species abound in the vicinity of sea bream (Sparus auratus) and sea bass (Dicentrarchus labrax) net pens feeding on waste feed and comprise the vectors for the transmission of the parasites to the farmed species. Heavy infestations of parasitic larvae may kill smaller fish when they first infect them, while seeking permanent attachment. Injured tissues are frequently invaded by secondary bacterial pathogens, such as Aeromonas sp., Flexibacter sp., Vibrio sp. and this may lead to severe escalation of mortality. In young stocks, the cumulative mortality due to parasitism by the pulii II larvae may run as high as 15% even without any bacterial implications. Isopod infestation is confirmed by gross observation of the parasites on the skin, mouth or in the gill chamber of the fish. Recommended prevention would be mainly by means of stock management measures. Excessive fish densities in the fry holding pens must be avoided. Often, in cases of heavy parasitism and mortality, reducing the fish density is enough by itself to remedy the situation. It is worth noting that on farms, where injection vaccination of sea bass is routinely performed, manual delousing of the anaesthetised fish, by means of small blunt forceps, prior to injecting results in a sharp drop of fish retaining adult isopods. Treatment of isopod larvae infestations has been attempted with considerable success by means of hourly formalin baths, at concentrations of about 150ppm, subsequent to enclosing the fish in a tarpaulin and providing ample water oxygenation. Laboratory and field experiments with deltamethrin (pyrethroid), in live fish and in isolated parasites, have indicated that the minimum effective in vitro dose, that kills Ceratothoa oestroides adults in 30 minutes, is 0.05mg/litre.

Betanodaviruses are the causative agents of viral nervous necrosis (VNN) in cultured marine fish. A total of 237 apparently healthy aquarium fish, marine (65 species) and freshwater (12 species) fishes and marine invertebrates (4 species), which were stocked in a commercial aquarium in Seoul, South Korea, were collected from November 2005 to February 2006. The brains of the fish and other tissues of the invertebrates were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR to detect betanodavirus. Positive nested PCR results were obtained from the brains of 8 marine fish species (shrimp fish Aeoliscus strigatus, milkfish Chanos chanos, three spot damsel Dascyllus trimaculatus, Japanese anchovy Engraulis japonicus, pinecone fish Monocentris japonica, blue ribbon eel Rhinomuraena quaesita, look down fish Selene vomer, yellow tang Zebrasoma flavesenes), 1 marine invertebrate species (spiny lobster Pamulirus versicolor), and 2 freshwater fish species (South American leaf fish Monocirrhus polyacanthus and red piranha Pygocentrus nattereri). The detection rate in nested PCR was 11/237 (4.64%). These subclinically infected aquarium fish and invertebrates may constitute an inoculum source of betanodaviruses for cultured fishes in the Korean Peninsula.

1. The present status of marine fish cultivation research in Japan is reviewed. 2. In marine fish farms, the stocks have been recruited from young fish caught at sea, but recently, artificially reared fry are more and more taking the place of natural young fish, in some species. 3. The main fish species cultivated in Japanese farms are yellow-tailSeriola quinqueradiata, pufferFugu rubripes rubripes and red sea breamPagrus major; they are mostly cultivated in floating net cages set in sheltered places. 4. To increase the natural resources, the release of artificially reared young of some fishes has just started in the Inland Sea of Japan. 5. Efforts are being made to obtain ripe eggs from reared marine fishes, to hatch fertilized eggs and to raise fry: Spawning, fertilization, hatching and raising to commercial size has been achieved in several important shallow water marine fishes. 6. To keep the ambient water suitable for hatching and raising of fishes, filtration, circulation, exchange of sea water and availability ofChlamydomonas sp. andChlorella sp. (to remove metabolic wastes of the fish and to supply oxygen) have been studied. 7. Research on food sources suitable for respective stages of fishes and on the methods of producing such foods have been made. Several marine organisms are cultivated in abundance as food sources for fishes. 8. Diseases of marine fishes have been studied to keep them healthy and to enhance survival rates. 9. Some experiments on the production of hybrids between different marine fish species are now in progress; several hybrids have already been produced artificially and reared successfully.

The measurement of bisphenol A and its analogues, perfluorinated compounds in twenty species of freshwater and marine fishes, a time-trend comparison and human health based assessment