Early life history of the black anglerfish Lophius budegassa Spinola, 1807 in the Mediterranean Sea using otolith microstructure

The early life history of the black anglerfish, Lophius budegassa was investigated by otolith (lapilli) increment analysis. Samples of demersal juvenile L. budegassa ranging from 54 to 196 mm total length were collected during bottom trawl surveys in the central Adriatic Sea. By counting increments presumed to be deposited daily in the lapillar otoliths, 88 specimens of L. budegassa were successfully aged. Age estimates of juveniles ranged between 79 and 204 days, indicating that probably the pelagic phase of this species is relatively short and settlement occurs at less than 3 months of life. The analysis of check marks in the core area of lapilli enabled us to determine the period of endogenous feeding, which would last between 15 and 24 days after hatching. Back-calculated hatching dates and, consequently, the spawning season of L. budegassa in the Adriatic Sea was spread over a long period, lasting at least from February to June. The length at age relationship gave an estimate of mean growth rate of approximately 0.8–1.02 mm/day, indicating a faster growth rate of 0+ juveniles L. budegassa than previously thought. The implications of these findings on age estimates discrepancies between previous ageing studies on L. budegassa carried out using different calcified structure (sagittae or illicia) are discussed.     

Spraguea (Microsporida: Spraguidae) infections in the nervous system of the Japanese anglerfish, Lophius litulon (Jordan), with comments on transmission routes and host pathology

Anglerfish from the genus Lophius are a globally important commercial fishery. The microsporidian Spraguea infects the nervous system of these fish resulting in the formation of large, visible parasitic xenomas. Lophius litulon from Japan were investigated to evaluate the intensity and distribution of Spraguea xenomas throughout the nervous system and to assess pathogenicity to the host and possible transmission routes of the parasite. Spraguea infections in L. litulon had a high prevalence; all fish over 403 mm in standard length being infected, with larger fish usually more heavily infected than smaller fish. Seventy percent of all fish examined had some gross visible sign of infection. The initial site of development is the supramedullary cells on the dorsal surface of the medulla oblongata, where all infected fish have parasitic xenomas. As the disease progresses, a number of secondary sites typically become infected such as the spinal, trigeminal and vagus nerves. Fish with infection in the vagus nerve bundles often have simultaneous sites of infection, in particular the spinal nerves and along the ventral nerve towards the urinary bladder. Advanced vagus nerve infections sometimes form xenomas adjacent to kidney tissue. Spraguea DNA was amplified from the contents of the urinary bladders of two fish, suggesting that microsporidian spores may be excreted in the urine. We conclude that supramedullary cells on the hindbrain are the primary site of infection, which is probably initiated at the cutaneous mucous glands where supramedullary cells are known to extend their peripheral axons. The prevalence of Spraguea infections in L. litulon was very high, and infections often extremely heavy; however, no associated pathogenicity was observed, and heavily infected fish were otherwise normal.     

First record of Tetramicra brevifilum in lumpfish (Cyclopterus lumpus,L.)

A microsporidian species with 98.3–98.4% nucleotide identity to Tetramicra brevifilum (Journal of Fish Diseases, 3 , 1980, 495) was diagnosed in lumpfish (Cyclopterus lumpus, L.) broodstock held at a breeding and rearing facility in western Ireland. The fish were wild‐caught from the west coast of Ireland, and the first case was diagnosed one year after capture. Clinical signs included severe bloating, lethargy, exophthalmos, anorexia, white patches on the cornea and externally visible parasitic cysts on skin and fins. Necropsy revealed severe ascites, white nodules and vacuoles in all the internal organs and partial liquefaction of the skeletal muscle. On histological examination, microsporidian xenomas were observed in all internal organs, the skin, skeletal muscle, gills and the eyes. The microsporidian species was identified by molecular analysis and transmission electron microscopy. This is the first record of T. brevifilum infecting lumpfish, and the disease is considered to be of potential significance to the rising aquaculture industry of this species.     

Weaning methods using formulated feeds for snakehead (Channa striata and Channa micropeltes) larvae

The culture of snakehead fish (Channa striata and Channa micropeltes) in Vietnam is limited, and snakehead culture has been banned in Cambodia, because traditional practices include capture of fingerlings from the wild as seed, as well as capture of small‐size (also known as trash fish or low‐value) fish. As hatchery breeding technology has improved, we investigated the optimal weaning practices for these two species. Both laboratory experiments and farm trials were conducted. For C. striata, the optimal weaning procedure is to begin at 17 days after hatch (dah) and wean the fish at 10% replacement of live feed with formulated feed per day. However, for C. micropeltes, the optimal procedure is to wait until 40 dah to begin weaning and then to wean the fish with a 10% replacement of live feed with formulated feed every 3 days. These results should enable farmers to domesticate snakehead culture in Vietnam and Cambodia and eliminate reliance on fish captured from the wild as both seed and feed.     

Does upwelling intensity determine larval fish habitats in upwelling ecosystems? The case of Senegal and Mauritania

European sardine (Sardina pilchardus) and round sardinella (Sardinella aurita) comprise two‐thirds of total landings of small pelagic fishes in the Canary Current Eastern Boundary Ecosystem (CCEBE). Their spawning habitat is the continental shelf where upwelling is responsible for high productivity. While upwelling intensity is predicted to change through ocean warming, the effects of upwelling intensity on larval fish habitat expansion is not well understood. Larval habitat characteristics of both species were investigated during different upwelling intensity regimes. Three surveys were carried out to sample fish larvae during cold (permanent upwelling) and warm (low upwelling) seasons along the southern coastal upwelling area of the CCEBE (13°–22.5°N). Sardina pilchardus larvae were observed in areas of strong upwelling during both seasons. Larval habitat expansion was restricted from 22.5°N to 17.5°N during cold seasons and to 22.5°N during the warm season. Sardinella aurita larvae were observed from 13°N to 15°N during cold seasons and 16–21°N in the warm season under low upwelling conditions. Generalized additive models predicted upwelling intensity driven larval fish abundance patterns. Observations and modeling revealed species‐specific spawning times and locations, that resulted in a niche partitioning allowing species' co‐existence. Alterations in upwelling intensity may have drastic effects on the spawning behavior, larval survival, and probably recruitment success of a species. The results enable insights into the spawning behavior of major small pelagic fish species in the CCEBE. Understanding biological responses to physical variability are essential in managing marine resources under changing climate conditions.     

Identification and pathogenicity study of emerging fish pathogens Acinetobacter junii and Acinetobacter pittii recovered from a disease outbreak in Labeo catla (Hamilton, 1822) and Hypophthalmichthys molitrix (Valenciennes, 1844) of freshwater wetland in West Bengal,India

The disease outbreaks in aquaculture system of wetlands are the major cause of fish mortality. Among various bacterial septicaemic diseases, fish mortality caused by Acinetobacter spp. is recently reported in different fish species. Fish disease outbreak was investigated in a wetland of West Bengal, India to identify the aetiological factors involved. The moribund fish were examined and subjected to bacterial isolation. Two bacterial causative agents were identified as Acinetobacter junii and Acinetobacter pittii by biochemical characterization and 16S rRNA gene amplification. Both the isolates were oxidase‐negative, nitrate‐negative, catalase‐positive and indole‐negative. The molecular identification using 16S rRNA gene sequencing and phylogenetic tree analysis further confirmed the two Acinetobacter spp. with 97%–99% similarity. The antibiotic resistance patterns of these two bacteria revealed that both of them were resistant to β‐lactam, cefalexin, cephalothin, amoxyclav, cefuroxime, cefadroxil, clindamycin, vancomycin and penicillin. In addition, A. pittii was also resistant to other antibiotics of cephams group such as ceftazidime and cefotaxime. In the challenge experiment, both A. junii and A. pittii were found to be pathogenic with LD₅₀ of 1.24 × 10⁵ and 1.88 × 10⁷ cfu/fish respectively. Histopathological examination of gill, liver and kidney revealed prominent changes supporting bacterial septicaemia. The investigation reports for the first time on concurrent infection by A. junii and multidrug‐resistant (MDR)‐A. pittii as emerging fish pathogens to cause severe mortality in Labeo catla and Hypophthalmichthys molitrix in a freshwater wetland.     

Substrate type and brightness preference of Schizothorax wangchiachii and Percocypris pingi juveniles

It is advantageous for fish to choose different substrate types and brightness based on their current life cycle stage, foraging requirements, predator avoidance and water conditions. We determined the substrate type and brightness preference of hatchery‐reared and wild juvenile Schizothorax wangchiachii and Percocypris pingi under laboratory conditions. Individuals and groups were exposed to four kinds of substrate types (sand: diameter < 1 mm, small gravel: diameter approximately 2–3 cm, large gravel: diameter approximately 10–15 cm, sand and medium gravel mix: diameter approximately 4–7 cm) and two kinds of substrate brightness (black and white). The results showed that hatchery‐reared and wild S. wangchiachii and P. pingi significantly preferred large gravel and black substrates regardless of the number of fish (p < .05). P. pingi had a significantly higher preference for black substrate than S. wangchiachii both in hatchery‐reared and wild individuals (p < .05). Hatchery‐reared and wild individuals of the two species shared a preference for large gravel and black substrates suggesting that substrate preferences might be genetically based. The findings in the present study could be used to improve the rearing conditions for the two species in hatchery and thereafter to enhance its adaptability after releasing to the wild.     

The control of floating macrophytes by grass carp in net cages: experiments in two tropical hydroelectric reservoirs

The efficiency of grass carp (Ctenopharyngodon idella Val.) for biological control of floating aquatic macrophytes in net cages was assessed in two eutrophic tropical hydroelectric reservoirs through experiments using three macrophyte species (Eichhornia crassipes, Pistia stratiotes and Salvinia auriculata). A total of twenty experiments were performed in these reservoirs with a duration period between 21 and 30 days, during distinct seasons of the year. Sets of experiments were conducted using the three macrophyte species simultaneously in both reservoirs, and additional experiments were performed in one reservoir involving the separate use of each species. All macrophytes demonstrated significant growth in the absence of fish with total per day biomass increase rate ranging from 0.06 to 17.00%. The presence of grass carp significantly reduced macrophyte biomass in both reservoirs independent of fish size, stocking rate and available cage space. In all seasons, grass carp grazing pressure was higher for S. auriculata and lower for P. stratiotes. The results show that grass carp in net cages was able to use aquatic macrophytes as the only food source, controlling massive plant growth (especially S. auriculata and E. crassipes). Fish cages, already implemented in several reservoirs in Brazil, are easily manageable units at relatively low cost. Thus, biocontrol of macrophytes using caged grass carp is proposed as an effective low‐budget ecotechnological tool to control consumable plants while avoiding the removal of desirable aquatic vegetation and the resultant impact on local fauna.     

Mycobacteria in aquarium fish: results of a 3‐year survey indicate caution required in handling pet‐shop fish

Fish are commonly infected with non‐tuberculous mycobacteria (NTM), which should be regarded as potential pathogens when handling aquarium fish and equipment. This study examined 107 aquarium fish from pet shops. Cultivation of the fish samples using different selective media was conducted for identification of NTM. Isolates were identified using the GenoType Mycobacterium common mycobacteria and additional species assays, sequencing of the 16S rRNA and rpoB genes, and real‐time PCR assay for identification of Mycobacterium (M.) marinum. Among the investigated fish, 79.4% (85/107) were positive for mycobacteria, with 8.2% (7 of 85) having two mycobacterial species present. Among the positive fish, the common pathogens M. marinum, Mycobacterium fortuitum (M. fortuitum group) and Mycobacterium chelonae were identified in approx. 90% of fish and other NTM species in 10%, including Mycobacterium peregrinum/septicum, Mycobacterium gordonae, Mycobacterium arupense, Mycobacterium kansasii, Mycobacterium ulcerans and Mycobacterium setense. The well‐known human pathogen M. marinum was present in 10.6% of the positive fish (9 of 85). The species of mycobacteria identified in the study are not only recognized as aquarium fish pathogens, but can also cause pathology in humans. Microbiological and clinical communities should therefore be sensitized to the role of NTM in infections associated with exposure to aquarium fish.     

Bathymetric distribution of demersal fish in the Aegean and Ionian Seas based on generalized additive modeling

Good knowledge of the spatial distribution of fish is critical to stock assessment and successful fisheries management. Depth is often the main gradient along which faunal changes occur when analyzing shelf and upper slope assemblages, and thus knowledge of the bathymetric distribution of fish species is of great importance. The depth distribution of 16 fish species (Chelidonichthys lucernus, Helicolenus dactylopterus, Hoplostethus mediterraneus, Lepidorhombus boscii, Lophius budegassa, Merlangius merlangus, Merluccius merluccius, Micromesistius poutassou, Mullus barbatus, Mullus surmuletus, Pagellus erythrinus, Peristedion cataphractum, Phycis blennoides, Serranus cabrilla, Trigla lyra, and Trisopterus minutus) of the Aegean and the Ionian Seas was evaluated by analyzing experimental bottom trawl data, using generalized additive modeling (GAM) techniques. A variety of bathymetric distribution patterns was observed. The main bathymetric zone of each species was defined based on the modeled relative density. Specifically, the lower and upper limits of the main bathymetric zone of each species were defined as the depths where the estimated relative density of the species becomes less than 1% of the maximum. This definition is proposed as a better and more informative alternative than reporting the minimum and maximum depths of encounter.     

Two epizootic Perkinsus spp. events in commercial oyster farms at Santa Catarina,Brazil

Perkinsus spp. have been detected in various bivalve species from north‐east Brazil. Santa Catarina is a South Brasil state with the highest national oyster production. Considering the pathogenicity of some Perkinsus spp., a study was carried out to survey perkinsosis in two oyster species cultured in this State, the mangrove oyster Crassostrea gasar and the Pacific oyster Crassostrea gigas. Sampling involved eight sites along the state coast, and oyster sampling was collected during the period between January 2013 and December 2014. For the detection of Perkinsus, Ray's fluid thioglycollate medium (RFTM) and histology were used, and for the identification of the species, PCR and DNA sequencing were used. Perkinsus spp. was found by RFTM in C. gigas and C. gasar from São Francisco do Sul. This pathology was also detected in C. gasar from Balneário Barra do Sul both, by RFTM and histology. Perkinsus marinus was identified in C. gigas and C. gasar from São Francisco do Sul and Perkinsus beihaiensis in C. gasar from Balneário Barra do Sul. This is the first report of P. marinus in C. gigas from South America. Results of this preliminary study suggest that both oyster species tolerate the species of Perkinsus identified, without suffering heavy lesions.     

Loma salmonae-associated xenoma onset and clearance in rainbow trout, Oncorhynchus mykiss (Walbaum): comparisons of per os and cohabitation exposure using survival analysis

Survival analysis techniques were used to compare experimental exposure methods of Loma salmonae (Microspora) in rainbow trout (RBT) by measuring xenoma onset and clearance time. Twenty‐eight naive RBT were exposed per os (fed L. salmonae spores) and 28 RBT were exposed by cohabitation with 28 L. salmonae‐infected RBT. Exposed fish were examined once every week (7 days) post exposure (PE). For xenoma onset, the median survival time, the time to first appearance of branchial xenomas, was 6 weeks PE for both per os and cohabitation exposure. For xenoma clearance, the median survival time, the time to total clearance of branchial xenomas, was 10 weeks for per os exposure and 12 weeks for cohabitation exposure. There was a significant difference between the survival curves of per os fish compared with cohabited fish for both xenoma onset and xenoma clearance. The incidence rate of xenoma development was greater for per os exposure (0.1745 cases per fish‐week) compared with cohabitation exposure (0.1342 cases per fish‐week). Similarly, the rate of xenoma clearance was greater for per os exposure (0.1028 cases per fish‐week) compared with cohabitation exposure (0.0885 cases per fish‐week). Differences between exposure methods were attributed to differences in the frequency and duration of exposure to spores. Survival analysis was useful for examining the onset and clearance of L. salmonae and may have applications for understanding disease dynamics in aquaculture.     

Outbreak of mass mortality of yearling groupers of Epinephelus (Perciformes,Serranidae) associated with the infection of a suspected new enteric Sphaerospora (Myxozoa: Myxosporea) species in South China Sea

A suspected new enteric Sphaerospora species was believed to be directly associated with the mass mortality of yearling groupers of Epinephelus spp. in South China. The epizootic generally emerged from late September to late April of the following year. The infection prevalence and mortality rate were significantly negatively correlated with fish size. Clinical signs included anorexia, cachexia and extrusion of white pulp‐like substance from anus after gentle pressure on the abdomen. Upon necropsy, severe intestinal oedema, thin and transparent intestinal wall, swollen spleen, kidney and gall bladder could be observed. Wet preparation of the infected samples showed large amount of typical disporous plasmodia of the genus Sphaerospora, but no mature spores were observed. Epidemiological investigation showed that this parasite exclusively infected Epinephelus groupers. Histopathologically, this species mainly infected the epithelium of intestine and kidney tubules and caused severe epithelia sloughing and the collapse of intestinal villus. Interestingly, this enteric myxosporidiosis did not cause severe emaciation of infected fish for mass mortality usually emerged within 2–3 days after appearance of clinical signs. The species was most genetically related to Sphaerospora fugu (89% sequence identity) and phylogenetically positioned within marine Sphaerospora lineage. This is the first report of enteric sphaerosporosis of groupers.     

Comparison of mudcrab‐based brackishwater polyculture systems with different finfish species combinations in Sundarban,India

To compare production and economic performance of polyculture systems with different species combinations, a 210‐day trial was carried out. In the first combination (T1), milkfish (Chanos chanos) and mudcrabs (Scylla serrata), and in the second (T2), mullets (Mugil cephalus, Liza tade and Liza parsia at 0.5:0.5:0.5 ratio) and mudcrabs were stocked keeping fish and mudcrabs at 15,000 numbers per ha, respectively, in both treatments. The finfish were fed floating pellet at 2%–3% and mudcrabs were fed fresh and farm made feed at 5%–8% body weight. Growth parameters of mudcrabs were similar in both T1 (407.64 ± 105.78 g) and T2 (418.89 ± 105.24 g), with no significant differences. Among finfish, M. cephalus attained highest final body weight, 241.55 ± 26.44 g followed by milkfish, 200.46 ± 11.82 g whereas lowest growth noticed in L. parsia (63.69 ± 6.62 g). Length–weight analysis of fish indicated negatively allometric growth (b < 3) for grey mullets, parsia and milkfish while L. tade recorded perfect cube low (b = 2.99). Male mudcrabs recorded positive allometric (b = 3.3) and female crab exhibited negative allometric growth (b = 2.68). The total productivity was 4,533 and 3,694 kg/ha with mudcrab contributes 53.69% and 60.56% to the total productivity in T1 and T2 respectively. The economic analysis indicated benefit–cost ratio (BCR) of 1.57 and 1.73 in T1 and T2 respectively with 10% and 35% insignificant increase (p > 0.05) in BCR and profit per kg, respectively, in T2 compared with T1. The study elucidates polyculture of mudcrabs with finfish can be a taken up as a profitable venture for sustainable diversification of brackishwater farming in Sundarbans.     

Morphological and genetic characterization of Hysterothylacium Ward & Magath, 1917 (Nematoda: Raphidascarididae) larvae in horse mackerel,blue whiting and anchovy from Spanish Atlantic and Mediterranean waters

The presence of zoonotic Hysterothylacium larvae in fish from Spanish Atlantic and Mediterranean waters, which can cause economic losses for commercial fisheries, has been reported in several studies; however, little is known about species identity in this region. The aim of this study was to identify at species level the Hysterothylacium morphotypes detected in three commonly consumed fish: horse mackerel (Trachurus trachurus), blue whiting (Micromesistius poutassou) and anchovy (Engraulis encrasicolus). Third‐ and fourth‐stage Hysterothylacium larvae, as well as adults obtained from larval in vitro culture, were morphologically and molecularly identified by ITS1/ITS2 rDNA sequencing. Four Hysterothylacium morphotypes were detected. Genetic analysis showed that morphotypes VIII and IX were different larval stages of Hysterothylacium aduncum, which was supported by cultured adult species identification. Morphotypes III and IV were found to correspond to different developmental stages of another species of Hysterothylacium. As all larval types detected were morphologically indistinguishable from others previously reported yet showed clear genetic differences, they are referred here as new genotypes. This is the first time that ITS‐sequence data of various developmental stages of the same species, including adults, have been studied and compared, providing crucial knowledge for future studies on Hysterothylacium identification and biology.     

First report of Shewanella sp. and Listonella sp. infection in freshwater cultured loach,Misgurnus anguillicaudatus

A novel disease outbreak occurred among cultured loach, Misgurnus anguillicaudatus in China. The diseased fish displayed lethargy, loss of appetite, black discolouration, anasarca and ventral skin hyperaemia. Clinical signs were observed in most of the fish examined, which consisted of discoloured liver, swollen spleen and petechial haemorrhage in the intestine and peritoneal membranes. The causative agent was found to be two species of bacteria by experimental infection, identified as Shewanella sp. and Listonella sp. The result showed that these were likely to be Shewanella putrefaciens and Listonella anguillarum respectively. Bacterial identification consisted of physiological and biochemical tests as well as 16S rRNA sequence analysis. In addition, antibiotic susceptibility testing was performed, revealing that Shewanella putrefaciens and Listonella anguillarum were susceptible to enrofloxacin, ciprofloxacin, levofloxacin, pipemidicacid and norfloxacin. This is the first report of S. putrefaciens and L. anguillarum from cultured loach.     

Characterization of spaC‐type Erysipelothrix sp. isolates causing systemic disease in ornamental fish

Since 2012, low‐to‐moderate mortality associated with an Erysipelothrix sp. bacterium has been reported in ornamental fish. Histological findings have included facial cellulitis, necrotizing dermatitis and myositis, and disseminated coelomitis with abundant intralesional Gram‐positive bacterial colonies. Sixteen Erysipelothrix sp. isolates identified phenotypically as E. rhusiopathiae were recovered from diseased cyprinid and characid fish. Similar clinical and histological changes were also observed in zebrafish, Danio rerio, challenged by intracoelomic injection. The Erysipelothrix sp. isolates from ornamental fish were compared phenotypically and genetically to E. rhusiopathiae and E. tonsillarum isolates recovered from aquatic and terrestrial animals from multiple facilities. Results demonstrated that isolates from diseased fish were largely clonal and divergent from E. rhusiopathiae and E. tonsillarum isolates from normal fish skin, marine mammals and terrestrial animals. All ornamental fish isolates were PCR positive for spaC, with marked genetic divergence (<92% similarity at gyrB, <60% similarity by rep‐PCR) between the ornamental fish isolates and other Erysipelothrix spp. isolates. This study supports previous work citing the genetic variability of Erysipelothrix spp. spa types and suggests isolates from diseased ornamental fish may represent a genetically distinct species.     

A bacterium with close genetic identity to Pseudomonas mandelii associated with spring fish kills in wild bluegill Lepomis macrochirus Rafinesque and pumpkinseed sunfish Lepomis gibbosus (Linnaeus)

Pseudomonas fluorescens are known bacterial pathogens in fish. The P. fluorescens group contains at least nine different bacterial species, although species from fish have rarely been differentiated. Two isolated fish kills affecting wild bluegills, Lepomis macrochirus Rafinesque, and pumpkinseed sunfish, Lepomis gibbosus (Linnaeus), occurred in the spring of 2015 during cool water temperatures (12.5°C–15.5°C). Disease signs included severe bacteraemia with rare gross external signs. Pure bacterial cultures isolated from kidneys of all affected fish were identified as P. fluorescens using the API 20NE system, while no bacteria were isolated from asymptomatic fish. To further identify the species of bacterium within the P. fluorescens complex, genetic analysis of the 16S rRNA, rpoD and gyrB genes was conducted. DNA sequences of bacterial isolates from both mortality events were identical and had close identity (≥99.7%) to Pseudomonas mandelii. Although likely widespread in the aquatic environment, this is the first report of a bacterium closely resembling P. mandelii infecting and causing disease in fish. The bacterium grew at temperatures between 5°C and 30°C, but not at 37°C. It is possible that infections in fish were a result of immunosuppression associated with spring conditions combined with the psychrotrophic nature of the bacterium.     

Isolation and evaluation of putative probiotic strains from different teleost to prevent Pseudomonas aeruginosa infection in Cyprinus carpio

Probiotics renowned as valuable microbes serve as a potential alternative to control diseases in aquaculture and are considered as an efficient and environment‐friendly approach to reduce the use of antibiotics. The present study aims at the isolation of putative probiotic bacteria from the intestinal tract of different fish species from the Doaba region of Punjab, India. In this study, isolated bacterial strains were characterized based on their morphological, biochemical and molecular characterization by 16S rRNA gene sequencing, followed by in vitro evaluation of different selection parameters described in FAO/WHO guidelines. A total of 169 different bacterial strains were isolated from the gastrointestinal tract of 52 different fish species. After in vitro evaluation, out of 169 bacterial strains only five bacteria (S3, S7, BDK2', BDK7 and BDK9) identified as Enterococcus and Bacillus species showed antagonistic activity against the fish pathogen Pseudomonas aeruginosa (MTCC 4 673). These isolates were screened based on their response towards bile tolerance, pH tolerance, adhesion and drug susceptibility to different antibiotic discs. And, the in vivo results indicated improved growth and survival against the infection (P. aeruginosa) after oral administration of the probiotics. The observations of in vitro and in vivo evaluation indicate that these isolated probiotic strains serve as effective probiotics and can be used as a novel and safe treatment to cure current issues in aquaculture.     

The hidden companion of non‐native fishes in north‐east Atlantic waters

A tropicalization phenomenon of ichthyofauna has been described in the last decades in Galicia (north‐eastern Atlantic), with increasing reports of tropical and subtropical fishes appearing northward this distribution range. A search for parasites was carried out in the digestive tract of two specimens first captured in Galician waters: the prickly puffer Ephippion guttifer (Tetraodontidae) and the African stripped grunt Parapristipoma octolineatum (Haemulidae). Examination of E. guttifer showed high intensity of nematodes, from three different genera: Cucullanus (Cucullanidae), Hysterothylacium (Raphidascaridae) and Anisakis (Anisakidae), with demonstrated pathogenicity to humans. Molecular identification allowed the identification of Anisakis pegreffii, already described in the area, and first reports for European waters of Cucullanus dodsworthi, Hysterothylacium reliquens and a new Hysterothylacium sp. P. octolineatum showed a far lower level of parasitization, with two Hysterothylacium larvae, genetically identified as Hysterothylacium deardorffoverstreetorum, also its first report in the eastern Atlantic. Thus, possible ecological impact of the occurrence of two non‐native individual fishes in a new area could be remarkably higher if we see this issue through the lens of the parasitological perspective, as far as only two individual fish can harbour more of one hundred nematode parasites belonging to different species, most of them also new species for that area.