Parasitic fauna of farmed freshwater ornamental fish in the northwest of Iran

Ornamental fish farming is globally a key sector of aquaculture. The purpose of this study was to report on the parasitic fauna of ornamental fish from seven farms in the East Azerbaijan province in northwestern Iran. Between November 2020 and February 2021, a total of 600 freshwater ornamental fish of six species, including goldfish (Carassius auratus), angel (Pterophyllum scalare), guppy (Poecilia reticulata), dwarf gourami (Colisa lalia), swordtail (Xiphophorus helleri), and cichlid (Cichlasoma sp.) were collected for parasitological analysis. Six ciliate protozoan species (Trichodina mutabilis, Trichodina nobilis, Trichodina spp., Heteropolaria lwoffi, Ichthyophthrius multifiliis, and Chilodonella spp.), three species of monogenean trematodes (Dactylogyrus dulkeiti, Dactylogyrus spp. and Gyrodactylus spp.), two species of crustacean arthropods (Lernaea cyprinacea and Argulus japonicus), and a nematode (Capillaria spp.) were identified among the examined fish. Parasites were detected in the fish from 5 of 7 farms, with an overall parasitic prevalence in 26.33% (158/600) of the fish. Fish infection rates with protozoans, monogenean trematodes, crustacean arthropods, and nematodes were 16.83, 13.17, 4, and 0.33% respectively. The highest prevalence was found in X. helleri infected with Gyrodactylus spp. and P. scalare infested with Trichodina spp. Moreover, 9/100 and 10/100 of goldfish were infected with A. japonicus and L. cyprinacea, compared to 2/500 and 3/500, respectively, for all other species in combination, which is a statistically significant result (p?<?0.01). Assessment of farmed fish parasitic fauna is important to inhibit the spread of infections, ensure fish production and improve fish health.

     

Effect of density on survival and growth of cyprinid fish fry

One of the bottlenecks in Israel's cold water ornamental fish industry is the large loss of fish during the post-larval stage. As a first step towards increasing survival rates, the optimal stocking density in earthen ponds for fry of each species should be determined. The results of five consecutive experiments with fry of goldfish (Carassius auratus), common carp and koi (respectively, edible and ornamental morphotypes of Cyprinus carpio) are presented here. The experiments were run in 18 cages of 1 m³ and 0.8 mm mesh size placed in a 0.02 ha earthen pond, stocked at 50,100 and 200 fry per cage. The variables analyzed were growth rate, harvesting weight, biomass and survival. Equations to estimate growth rates under different conditions are given. The three fish types present different growth rates and survival patterns in relation to stocking density and season, which lead to different management implications. Koi can be stocked up to 2 million fry per ha without showing negative density effects. Goldfish should be stocked at low density (500,000–1 million fry per ha) in spring and at higher rate (2 million fry per ha) in summer. Common carp stocking density should be adjusted to obtain the required fish size at harvest.     

Comparison of food selection and growth performance of koi carp, Cyprinus carpio L., and goldfish, Carassius auratus (L.) in mono- and polyculture rearing in tropical ponds

To compare the effect of polyculture against conventional monoculture on ornamental carp production, investigations on food selection and growth performance of koi carp (K), Cyprinus carpio L. and goldfish (G), Carassius auratus (L.) were conducted in a 11‐week rearing experiment in two monoculture (100% K and 100% G) and five polyculture (90% K–10% G, 70% K–30% G, 50% K–50% G, 30% K–70% G and 10% K–90% G) conditions in tropical ponds. There were three replicates for each treatment. Environmental conditions and food availability were similar in all the treatments. Ivlev's electivity index showed that both fish species avoided phytoplankton and preferred cladocerans to other zooplankton groups (copepods and rotifers) in monotypic conditions. However, in the polyculture treatments, the positive electivity of goldfish towards cladocerans reduced significantly (P<0.05), while the percentage of copepods, rotifers and phytoplankton in the gut content increased. No significant differences in weight gain, specific growth rate and deformities were recorded at harvest for koi carp between the different treatments (P>0.05). Even the survival rate of koi carp recorded above 90% in all the treatments. However, the goldfish recorded significantly better weight gain, specific growth rate and survival in monoculture (100% G), compared with the polyculture treatments (P<0.05). Goldfish deformities were lowest (P<0.05) in the monoculture treatment (2.42%). The number of marketable fish above a set size limit of 4 g total weight was significantly higher in the two monoculture treatments, compared with the five polyculture treatments (P<0.05). Keeping in view of the dietary similarities of koi carp and goldfish, and the aggressive nature of koi carp in polyculture, it is suggested to refrain from polyculture of goldfish and koi carp until further documentations relating to optimum stocking density and management of polyculture of ornamental carps are available.     

Colouring ornamental fish (Cyprinus carpio and Carassius auratus) with microalgal biomass

Koi carp and goldfish value increases with intensity of skin colour, which is an important quality criterion. Fish cannot fully synthesize their own carotenoid colourings and these must therefore be included in their diet. Two trials were undertaken to investigate skin colour enhancement in ornamental species (i.e. three chromatic varieties of koi carp (Cyprinus carpio), namely Kawari (red), Showa (black and red) and Bekko (black and white) and goldfish (Carassius auratus)) by feeding a dietary carotenoid supplement of freshwater microalgal biomass [Chlorella vulgaris, Haematococcus pluvialis, and also the cyanobacterium Arthrospira maxima (Spirulina)], using a diet containing synthetic astaxanthin and a control diet with no colouring added for comparison. In the first trial, five homogeneous duplicate groups of 25 juvenile koi carp (C. carpio) (initial mean body weight 24.6 ± 0.7 g) were fed, for 10 weeks, one of the four diets containing 80 mg colouring/kg diet. In the second trial, this procedure was repeated for five homogeneous duplicate groups of 25 goldfish (C. auratus) (initial mean body weight of 0.9 ± 0.1 g). Initial and final samples of skin along the dorsal fin were withdrawn, from five fish per group, for subsequent analysis of total carotenoid content (spectrophotometric analysis), and red hue (colorimetric analysis, CIE (1976) L* a* b* colour system). Growth and feed efficiency were not significantly different between groups administered by the various dietary treatments. In both trials, dietary carotenoid supplementation increased total skin carotenoid content. The more efficient colouring for koi carps was found to be C. vulgaris biomass, providing both maximum total carotenoid deposition and red hue for the three chromatic koi carp varieties studied, and particularly for the kawari variety. For goldfish the best colouring obtained, as ascertained by total carotenoid content, was also achieved using C. vulgaris biomass, and red hue was maximum when using H. pluvialis biomass.     

Fluctuating asymmetry, abnormalities and parasitism as indicators of environmental stress in cultured stocks of goldfish and carp

Knowledge about the effects of captivity and environmental stress on fish populations is basic to culture them for ornamental, conservation or exploitation purposes. The aim of this study was to test how captivity affect morphological development of bilateral characters and whether levels of fluctuating asymmetry, morphological abnormalities and ectoparasites reflect developmental stress caused by adverse environmental conditions in two species of cyprinids, goldfish Carassius auratus and two varieties of carp Cyprinus carpio, scale and mirror carp. Samples from captivity were caught in an artificial pond (Madrid City, Spain), which presents poor environmental conditions; while samples from nature were captured in the Ebro River basin (NE Spain). Six meristic and four morphometric bilateral characters were measured and compared between the two samples. Additionally, the incidence of morphological abnormalities and ectoparasites was also recorded. Captive goldfish presented significant lower number of scales of the lateral line, scale rows above lateral line and length of pectoral and ventral fins. Captive carps showed significant shorter first barbels and longer ventral fins. Ornamental goldfish showed significant higher levels of fluctuating asymmetry than wild samples for number of branched rays of pectoral fin, lateral line, scale rows below lateral line and length of pectoral and ventral fins. Ornamental carps presented a similar trend for the same characters, except for branched rays and length of pectoral fins, together with the length of second barbels. In the artificial pond, the incidence of abnormalities was higher in carp, whereas goldfish showed a higher occurrence of ectoparasites. These facts support the hypothesis of a different species response to environmental stress. The overall results indicate that fish from the artificial pond are subjected to environmental stress caused by adverse conditions such as overcrowding and lower water quality. Moreover, estimated parameters in this study mean a useful tool to detect developmental instability in confined fish.     

A comparison of growth, survival rate and number of marketable koi carp produced under different management regimes in earthen ponds and concrete tanks

To compare the growth performance of koi carp, Cyprinus carpio var. koi, produced in concrete tanks (2.13 × 0.91 × 1.22 m; capacity: 2,000 l each) and earthen ponds (9.1 × 6.10 × 1.07 m; capacity: 59650 l each), fish larvae (stocking size: 0.12 ± 0.008 g) were cultured for 11 weeks and individual weight gain, survival rate and number of marketable fish produced were compared among four management regimes for each culture system: (1) live zooplankton fed to fish larvae in ponds (PLF) and tanks (TLF); (2) application of poultry manure in ponds (PPM) and tanks (TPM); (3) application of cow manure in ponds (PCD) and tanks (TCD); and (4) a control treatment for ponds (PC) and tanks (TC), where a commercial feed was applied. There were three replicates for each treatment. Weight gain of koi carp was highest in the PLF treatment, followed in decreasing order by TLF, PPM, PCD, TPM, TCD, PC and TC treatments (P < 0.05). There was a significant difference in the survival of koi carp among the treatments, ranging from 67.83% in TC to 95.50% in PLF. The number of marketable fish produced was highest in the PLF treatment, followed in decreasing order by TLF, PPM and PCD treatments. However, none of the fish produced in the TPM, TCD, PC and TC treatments attained marketable size. Significantly higher (P < 0.05) values of pH and dissolved oxygen (for water samples collected weekly at 9 A.M.) were obtained in the live food and control treatments (for both tanks and ponds), compared to the manured treatments. The concentration of total alkalinity, BOD, PO₄-P, NO₃-N and specific conductivity were significantly higher (P < 0.05) in PPM and PCD, compared to other treatments. NO₂-N and NH₄-N values were significantly higher (P < 0.05) in TPM and TCD, than other treatments. The results suggest that introduction of live zooplankton into culture units result in higher growth of koi carp larvae compared to manure based systems. Earthen ponds appeared to be better alternative to concrete tanks for manure application through maintenance of better water quality due to their higher assimilatory capacity and greater abundance of plankton which resulted in better growth of cultured fish.     

锦鲤墨蝶呤还原酶基因的克隆、表达和定位分析

为探究SPR在锦鲤体色形成中的作用,实验利用RACE技术获得spr cDNA全长序列,并分析其时空表达模式,同时利用Western blot和免疫组织化学方法检测SPR蛋白在皮肤、鳍条和鳞片中的分布和表达情况。结果显示,spr cDNA全长879 bp,包含132 bp和134 bp的5′和3′非编码区,开放阅读框510 bp,编码170个氨基酸残基。氨基酸序列比对和系统进化树分析显示,锦鲤SPR具有保守的adh_short_C2结构域,与金鱼相似性高达97.7%。spr在各组织中均有表达,其中皮肤的表达量最高。spr在锦鲤个体发育的4个阶段表现为先降后升。纯红、纯白及红白3种体色锦鲤皮肤、鳞片和鳍条中spr mRNA和蛋白表达水平基本一致,在纯红锦鲤皮肤中表达量最高,红白锦鲤白色皮肤、鳞片和鳍条的表达量最低。SPR组织定位分析显示,红色锦鲤和白色锦鲤皮肤中均检测到阳性信号,其中红色皮肤阳性信号强度高于白色皮肤。研究表明,spr可能与锦鲤红/黄色素细胞的分化和形成具有一定相关性,参与了锦鲤体色的形成。     

Identification of a novel cyprinid herpesvirus 3 genotype detected in koi from the East Asian and South‐East Asian Regions

Cyprinid herpesvirus 3 (CyHV‐3) is a highly contagious virus that causes significant morbidity and mortality in common carp Cyprinus carpio L. and considered to be one of the most important pathogens of koi and common carp worldwide. Cyprinid herpesvirus 3 infected consignments imported from East Asian and South‐East Asian regions were identified during quarantine period in Singapore, and virus from a 2005 consignment was successfully isolated in koi fin cells. A combination of sequence analyses and duplex PCR were used to characterize 15 CyHV‐3 isolates detected in koi consignments between 2005 and 2011. Sequence analyses of the enlarged 9/5, SphI‐5 and TK gene regions identified both the Asian 1 (n = 11) and European 4 (n = 4) genotypes. Duplex PCR analysis of two variable marker regions between ORF29 and ORF30 (marker I) as well as ORF133 and its upstream region (marker II) revealed viruses of genotypes J (I⁺⁺II⁺), U/I (I⁻⁻II⁻), an intermediate genotype (I⁺⁺II⁻) and a novel genotype, I⁺⁺II^+Δ, which was identified in viruses from seven different consignments. This novel genotype has a 13‐bp deletion in marker II, while maintaining the I⁺⁺ allele of marker I. The I⁺⁺II^+Δ genotype may have emerged from East Asian and South‐East Asian regions in recent years.     

蛙病毒PCR检测方法的建立与比较分析

为了进一步丰富蛙虹彩病毒检测方法，实验针对蛙病毒3型(frog virus 3,FV3)核衣壳蛋白(major capsid protein,MCP)基因保守区设计一对特异性引物，并选取另外2种蛙病毒PCR检测方法进行对比实验，通过反应体系的优化、反应特异性和敏感性实验，建立了一种针对FV3的PCR检测方法。结果显示，该方法最低检测限可达1.2个拷贝数的病毒粒子，与神经坏死病毒、虾血细胞虹彩病毒、大口黑鲈虹彩病毒、锦鲤疱疹病毒、鲤浮肿病毒、传染性脾肾坏死病毒、加州鲈弹状病毒等常见水产动物致病毒株无交叉反应。临床样品检测表明，该方法所获得的检测结果与另外2种方法一致，结果可靠。本研究所建立的FV3 PCR检测方法，具有简便、快速、敏感度好、特异性高、低成本等特点，可用于FV3蛙病毒的快速诊断和分子流行病学调研。     

Isolation and characterization of a ranavirus from koi,Cyprinus carpio L., experiencing mass mortalities in India

We investigated mass mortalities of koi, Cyprinus carpio Linnaeus, 1758, experienced in South Indian fish farms by virus isolation, electron microscopy, PCR detection, sequencing of capsid protein gene and transmission studies. Samples of moribund koi brought to the laboratory suffered continuous mortality exhibiting swimming abnormalities, intermittent surfacing and skin darkening. Irido-like virus was isolated from the infected fish in the indigenous snakehead kidney cell line (SNKD2a). Icosahedral virus particles of 100 to 120 nm were observed in the infected cell cultures, budding from the cell membrane. Virus transmission and pathogenicity studies revealed that horizontal transmission occurred associated with mortality. PCR analysis of infected fish and cell cultures confirmed the presence of Ranavirus capsid protein sequences. Sequence analysis of the major capsid protein gene showed an identity of 99.9% to that of largemouth bass virus isolated from North America. Detection and successful isolation of this viral agent becomes the first record of isolation of a virus resembling Santee–Cooper Ranavirus from a koi and from India. We propose the name koi ranavirus to this agent.     

Koi herpesvirus: distribution and prospects for control in England and Wales

Koi herpesvirus (KHV) causes a highly virulent disease affecting carp, Cyprinus carpio L., and poses a serious socio‐economic threat to the UK carp industry. This study aimed to determine the geographic distribution and prevalence of KHV exposed fish in England and Wales through ELISA antibody testing. Only three of the 82 farms sampled produced positive results, suggesting fish farms provide a relatively safe source of fish. Of the 71 ‘high‐risk’ fisheries tested, 26 were positive. All eight geographic areas within England and Wales studied had at least one KHV positive site. Twelve consignments of imported koi carp from seven S.E. Asian countries were tested for KHV antibody. Six consignments from six different countries were positive. Although a high proportion of consignments were positive, the results indicate that lower risk stocks of fish exist that could be sourced by the ornamental carp sector. The study provides evidence that KHV is widespread and prevalent in ‘high‐risk’ fisheries. There are, however, prospects for controlling KHV as English and Welsh farms appear to be relatively free of the virus, and in most cases fish are not moved from fisheries to other waters.     

Susceptibility of koi × crucian carp and koi × goldfish hybrids to koi herpesvirus (KHV) and the development of KHV disease (KHVD)

Hybrids of koi, Cyprinus carpio × crucian carp, Carassius carassius and koi × goldfish, Carassius auratus, proved to be susceptible to koi herpesvirus (KHV, syn. CyHV‐3) and developed KHV disease (KHVD). While hybrids of koi × goldfish were partly resistant to mortality following infection by immersion, most koi × crucian carp hybrids died after bath infection. KHV DNA was detected in dead fish but also in all surviving animals by different polymerase chain reactions (PCRs). According to these results, hybrid crossbreeding does not seem to prevent severe losses associated with KHV in terms of inducing KHVD. The present study showed severe losses after a waterborne KHV infection of between 35% and 100% in koi × goldfish and koi × crucian carp hybrids as well as in SPF carp.     

Treatments for ectoparasites and diseases in captive Western Australian dhufish

The Western Australian dhufish (Glaucosoma hebraicum), an open-water marine finfish, has been identified as a potential species for aquaculture and a 4 y research project has concentrated on broodstock collection and maintenance, spawning and larval rearing. This paper describes treatments which were developed for the ectoparasites and diseases of broodstock fish. These included bacterial and fungal infections, Cryptocaryon irritans, Haliotremasp., an unidentified axinid monogenean, the isopod Aega cyclops and copepod Caligus sp. Treatments based on betadine, formalin, freshwater, malachite green, oxytetracycline (terramycin), 2-phenoxyethanol, potassium permanganate and trichlorphon (neguvon) were all tried. The most effective treatments against parasites were a freshwater bath or a combined freshwater bath and anaesthesia with 2-phenoxyethanol. Monogeneans on the gills were difficult to control and exophthalmia was an unresolved problem.     

Effects of experimental infection by Caligus rogercresseyi (Copepoda: Caligidae) on the common jollytail, Galaxias maculatus (Osmeriforme: Galaxiidae) (Jenyns, 1842) in Chile

Galaxias maculatus, the common jollytail, is a native smelt fish with a lacustrine or diadromous life cycle. In Chile, the rearing cycle of this fish includes a freshwater and a marine phase. Several diseases and parasites reported for the freshwater phase could be avoided by rearing the fish in salty or brackish water. Nonetheless, this alternative could result in Caligus rogercresseyi infections. The objective of this study was to evaluate experimentally the capacity of C. rogercresseyi to infect the common jollytail and the effects this parasite may cause to the fish. Prevalence and intensity of experimental C. rogercresseyi infections on G. maculatus were estimated and the effects of this parasitosis on the fish were evaluated on fish survival, weight loss, swimming behavior, and skin damage. Two experiments were carried out with adult fish taken from the Maullín Estuary. Fish were acclimatized to a salinity of 32 ppt and divided into two groups of 20 fish each. The experimental group was infected with copepodid stages of C. rogercresseyi and the other was used as a control. The fish were kept in individual tanks until observing ovigerous female copepods. C. rogercresseyi recognizes G. maculatus as a host under experimental conditions and optimal salinity for the parasite. Results show that under experimental condition copepodid stage can successfully infect the fish, developing to the adult stage, mating, and producing eggs (females). C. rogercresseyi caused alterations in fish behavior, superficial body damage, weight loss, and mortality. Rearing the common jollytail in salty water should take into consideration measures to control these infections as they can damage fish and affect surrounding wild fish populations. There are no records of this parasite in natural common jollytail populations; however, our understanding of the ecological role played by the common jollytail in C. rogercresseyi transmissions among sympatric host species could be greatly improved through further research related to host preferences and epidemiological data for different sympatric host species.     

Reproductive ability of triploid ornamental (koi) carp (Cyprinus carpio L.) × goldfish (Carassius auratus L.) hybrids and characteristics of their offspring

The purpose of this study was to investigate reproductive ability of backcross triploid koi (Cyprinus carpio L.) × goldfish (Carassius auratus L.) hybrids. These triploids have been obtained by crossing of F₁ hybrid females producing diploid eggs with males of parental species. Triploid hybrid females, when crossed with goldfish or koi males, produced mostly aneuploid fish with ploidy range from approximately 2.2n–3.2n with a mean value 2.5n; some fish in crosses of triploid females with koi males were tetraploid (4.0n). Since analysed fish had in their genomes one haploid set from parental males, the data indicate that triploid hybrid females mostly produced aneuploid eggs with ploidy range from approximately 1.2n–2.2n and a mean ploidy around 1.5n while some eggs were triploid. Triploid hybrid males were completely sterile and have not released any sperm after hormonal injection. Despite their low viability, some aneuploid fish obtained from triploid hybrid females were raised in indoor recirculating systems until the age of 2 years and their reproductive ability has been evaluated. One aneuploid female with ploidy 2.1n produced larvae with ploidy range from 2.9n to 3.4n with a mean ploidy of 3.1n when crossed with a koi male; about 60% of obtained larvae had ploidy from 3.0n to 3.2n. These data indicate that this female produced mostly eggs with unreduced ploidy level.     

The risk of parasite transfer to juvenile fishes by live copepod food with the example Triaenophorus crassus and Triaenophorus nodulosus

Natural zooplankton is a potential food resource for juvenile fish in fish farms as it is a good source of fats, carbohydrates, and protein. However, it is also a potential source of parasites and pathogens. The present study was conducted (1) to estimate the risk of parasite transfer by live copepod food under intensive farming conditions using the parasites Triaenophorus crassus and Triaenophorus nodulosus as example and (2) to look for strategies to avoid parasite infestation of juvenile fish.An easy and routinely applicable aniline blue staining method was developed to check the infestation levels of copepods with procercoids during the on-growing season of juvenile fish. From the copepod species occurring in zooplankton Cyclops spp. was infested frequently (9.4 ± 12.0%, maximum 38.7%), Diaptomus spp. infrequently (1.5 ± 1.6%, maximum 3.2%), Daphnia spp. never. Juvenile grayling, Thymallus thymallus, and corgonids, Coregonus sp., which had been fed with natural zooplankton revealed infestations rates with T. crassus of circa 5%, with T. nodulosus of circa 10%. As the occurrence of procercoids in the zooplankton was temporary limited, Triaenophorus infestation can be avoided by using artificial food instead of live copepods during the risky season.To prevent parasite infestation of juvenile fish methods were investigated to eradicate procercoids from copepods by chemical treatment (sodium chloride, hydrogen peroxide, citric acid treatment) and by freeze-thawing methods. Chemical methods failed to remove procercoids. In fish, which had been fed with frozen thawed zooplankton, no Triaenophorus spp. infestation was observed. Their survival rates were similar as in the control fed with live zooplankton, however the weight of the fish was significantly lower.     

Antibiotic resistance and repetitive‐element PCR fingerprinting in Aeromonas veronii isolates

This study evaluated antibiotic resistance and the related genes in total 47 Aeromonas veronii isolates from pet fish, eel (Anguilla japonica) and koi (Cyprinus carpio) in Korea. In comparison with the antibiotic susceptibilities of isolates from eel and koi, those of pet fish were more resistant to ceftiofur, aminoglycosides, tetracycline and nitrofurantoin. And isolates from pet fish showed high prevalences of class 1 integron, quinolones and tetracycline resistance determinants than those from eel and koi. Repetitive‐element palindromic PCR (rep‐PCR) showed larger diversities among A. veronii isolates. Collectively, pet fish may be a reservoir for multiple clones of A. veronii involved in antibiotic resistance. In this aspect, imported fish in the aquaculture trade should be steadily and continually screened for bacterial antibiotic resistance and related genes.     

黑棘鲷内脏结节病病原的分离、鉴定及致病性研究

2017年4月,浙江台州某海水养殖公司跑道式养殖池黑棘鲷大量发病,病鱼活力下降、食欲减退、体表溃疡,剖检可见肝脏、脾脏、肾脏肿大且有不同程度的白色结节,同时伴随大量腹水。用胰蛋白胨大豆琼脂(TSA)从典型结节病濒死黑棘鲷器官分离到革兰阴性短杆菌。分离病原菌AS15对健康黑棘鲷的致病力结果显示,AS15腹腔注射可使健康黑棘鲷发病死亡,死亡黑棘鲷可出现自然发病症状,在(24±1)°C的条件下,(25±2) g黑棘鲷的半数致死浓度(LD_(50))为6.5×10~4 CFU/尾。经API 20E鉴定,分离菌株AS15生理生化特性与类杀鱼爱德华氏菌LADL05-105和迟缓爱德华氏菌典型菌ATCC15947相似度为86.2%,与杀鱼爱德华氏菌ET~T883的相似度为82.8%;AS15的16S rDNA与杀鱼爱德华氏菌ET~T883同源性达99%,gyrB与类杀鱼爱德华氏菌LADL05-105和杀鱼爱德华氏菌ETT883同源性分别为100%和98%;16S rDNA进化树显示,AS15与ETT883、LADL05-105聚为一簇,gyrB进化树与LADL05-105、NCIM2056聚为一簇;采用4种爱德华氏菌属种特异性引物对AS15进行PCR分析,结果显示,AS15可扩增出类杀鱼爱德华氏菌的种特异性片段,不能扩增出迟缓爱德华氏菌、鲇鱼爱德华氏菌、杀鱼爱德华氏菌的种特异性片段,表明AS15属类杀鱼爱德华氏菌成员。分析了AS15的菌毛基因、sodB等毒力基因,发现AS15具有fimA、fimB、fimC、fimD等4种菌毛基因和sodB、citC、esrB、mukF、katB等毒力基因。本实验首次从黑棘鲷上检出致病性类杀鱼爱德华氏菌,该菌对黑棘鲷的发病机制和毒力机理还需进一步研究。     

Establishment and characterization of a heart-derived cell line from goldfish (<Emphasis Type="Italic">Carassius auratus</Emphasis>)

The goldfish Carassius auratus, a freshwater fish in the family Cyprinidae, was one of the earliest fish to be domesticated for ornamental purposes. A cell line was established from goldfish heart (GH) tissue to create a biological monitoring tool for viral diseases. The GH cell line was optimally maintained at 25 °C in M199 medium supplemented with 10–20% fetal bovine serum. A chromosomal analysis indicated that the cell line remained diploid, with a mean chromosomal count of 100. In viral inoculation assays, significant cytopathic effects (CPEs) were caused by epizootic hematopoietic necrosis virus (EHNV), Andrias davidianus iridovirus (ADIV), and Bohle iridovirus (BIV) infections in the fish cells and the viral titers (average value) of EHNV, ADIV, and BIV in GH cells reached 10^5.0, 10^4.5, and 10^5.0 TCID₅₀/0.1 mL, respectively, within 7 days. However, no CPE was observed in the cells infected with viral hemorrhagic septicemia virus (VHSV), infectious hematopoietic necrosis virus (IHNV), spring viremia of carp virus (SVCV), infectious pancreatic necrosis virus (IPNV), channel catfish virus (CCV), or grass carp reovirus (GCRV). These results suggest that the GH cell line is a valuable tool for studying viral pathogenesis.     

Case studies of spinal deformities in ornamental koi,Cyprinus carpio L.

This is a study of vertebral deformities in ornamental koi based on computed radiography and skeletons cleaned by dermestid beetles (Dermestes maculatus). All koi developed gradual onset of swimming abnormalities as adults. Extensive intervertebral osteophyte formation correlated with age of fish and was associated with hindquarter paresis in one koi. Vertebral compression and fusion were the most common spinal deformities occurring at multiple sites, similar to findings in other farmed fish. Site‐specific spinal deformities were thought to develop due to differences in swimming behaviour and rates of vertebral growth. One koi had offspring with spinal deformities. Spinal deformities are significant problems in both European and Australian food fish hatcheries. The heritability of vertebral deformities in farmed fish is reportedly low unless there is concurrent poor husbandry or nutritional deficiencies. The specific aetiologies for vertebral deformities in koi in this study could not be ascertained. Current knowledge on spinal deformities in the better studied European food fish species suggests multifactorial aetiologies. Future research should include prospective longitudinal studies of larger numbers of koi from hatch and consideration of all potential risk factors such as husbandry, nutrition, temperature, photoperiod and genetics.