Freshwater Ornamental Fish Research Articles

In Silico characterization of growth hormone from freshwater ornamental fishes: Sequence analysis, molecular modelling and phylogeny

In Silico characterization of growth hormone from freshwater ornamental fishes: Sequence analysis, molecular modelling and phylogeny

Biology and culture of the clown loachChromobotia macracanthus(Cypriniformes, Cobitidae) : 1- Hormonal induced breeding, unusual latency response and egg production in two populations from Sumatra and Borneo Islands

The clown loach Chromobotia macracanthus, endemic to Indonesia, is a major species on the international market of ornamental freshwater fish. In order to satisfy an increasing demand with a sustainable alternative to the massive capture of wild juveniles, research has been dedicated to the artificial propagation and domestication of this species. The present study, the first of a series, focused on favourable maintenance conditions for broodfish sexual mat- uration, criteria for identification of ripe fish, efficiency of hormone-induced breeding treatments, predictability of their latency response, and on the comparison of reproductive performances of fish from populations of Sumatra and Borneo Islands (in total, 112 females of 46 to 404 g body weight). When reared in fully controlled conditions in large water recirculation systems, broodfish originating from Sumatra had reproductive performances similar to or slightly higher than those maturing in the wild (ovulation rate of 93% vs. 82%, relative fecundity of 109 277 vs. 103 550 ova kg −1 and fertilization rate of 73% vs. 61%, respectively). In the same rearing conditions, captive females from Borneo (n = 22) showed lower ovulation rate (77%), relative fecundity (76 262 ova kg −1 ) and fertilization rate (50%) than those originat- ing from Sumatra (n = 28). By contrast, the mean individual weight of ova (around 0.8 mg) was independent from the origin or maintenance conditions of females. An initial modal follicle diameter ≥1.02 mm generally led to high ovula- tion success (>80%) after hormonal treatment and is recommended as the main criterion for selecting female broodfish. Two hormonal treatments for inducing oocyte maturation and ovulation (T1: two successive injections of Ovaprim at a 6 h-interval; T2: one injection of human chorionic gonadotropin (hCG)- and one of Ovaprim 24 h later), produced sim- ilar results in terms of ovulation rate, quantity and quality of ova collected. With both treatments, the latency decreased with increasing water temperature, then increased again at temperatures >28−29 ◦ C. To our knowledge, such U-shaped relationship between the latency response and temperature has never been documented in teleost fishes.

Carotenoids Pigmentation in Polyacanthus Fasciatus during Spawning Period

–Development of pigmentation during the spawning seasons in Polyacanthus fasciatus, a freshwater ornamental fish, has been studied from January till the end of the spawning season or the spent phase of the fish. The fish showed the development of colouration from the end of January and a high concentration of the same has been observed from March, April and May. The pigmentation i.e the total carotenoids was measured from the visible absorption at 450 nm taking 2500 E 1%/ 1cm value from the lipid extracts of scales, fins, muscle and ovary . There is high deposition of carotenoids pigmentation in their eggs. In all tissue, organs, scales and fins the pattern of accumulation of carotenoids started from the beginning of February till the end of spawning season Keywords––Carotenoids, Ornamental fish, Polyacanthus fasciatus, spawning season

Virulence potential and antibiotic susceptibility pattern of motile aeromonads associated with freshwater ornamental fish culture systems: a possible threat to public health.

Aeromonas spp. are ubiquitous aquatic organisms, associated with multitude of diseases in several species of animals, including fishes and humans. In the present study, water samples from two ornamental fish culture systems were analyzed for the presence of Aeromonas. Nutrient agar was used for Aeromonas isolation, and colonies (60 No) were identified through biochemical characterization. Seven clusters could be generated based on phenotypic characters, analyzed by the programme NTSYSpc, Version 2.02i, and identified as: Aeromonas caviae (33.3%), A. jandaei (38.3%) and A. veronii biovar sobria (28.3%). The strains isolated produced highly active hydrolytic enzymes, haemolytic activity and slime formation in varying proportions. The isolates were also tested for the enterotoxin genes (act, alt and ast), haemolytic toxins (hlyA and aerA), involved in type 3 secretion system (TTSS: ascV, aexT, aopP, aopO, ascF-ascG, and aopH), and glycerophospholipid-cholesterol acyltransferase (gcat). All isolates were found to be associated with at least one virulent gene. Moreover, they were resistant to frequently used antibiotics for human infections. The study demonstrates the pathogenic potential of Aeromonas, associated with ornamental fish culture systems suggesting the emerging threat to public health.

Mitochondrial DNA reveals low population differentiation in elongate loach, Leptobotia elongata (Bleeker): implications for conservation

Elongate loach (Leptobotia elongata (Bleeker)), an endemic fish species to China, is a famous ornamental freshwater fish. Here, a comparative study of mtDNA control region (D-loop) (835 bp) sequences was performed to analyze its wild population structure and evaluate the genetic diversity for 110 individuals from five locations in the upper reaches of the Yangtze River, China. A total of 49 polymorphic sites and 45 haplotypes yielded high haplotype diversity (h = 0.952), but low nucleotide diversity (π = 0.00454) as that of many fish species. Sequence divergences between haplotypes ranged from 0.0033 ± 0.0011 to 0.0050 ± 0.0012 in intra-groups, and from 0.0037 ± 0.0.0011 to 0.0050 ± 0.0012 between groups. Significant values of Tajima’s D (−1.86383, P < 0.01) and Fu’s F S (−25.93, P < 0.01), together with uni-modal mismatch distribution, indicated a recent genetic bottleneck or population expansion of the species. Analysis of molecular variance (AMOVA) indicated a small amount of differentiation among groups (1.7%); most of the total variation occurred within groups (98.3%). Also, there was no significant population structure (F ST = 0.017, P > 0.05), and estimates of gene flows among groups were extremely high (Nm = 28.88), suggesting low genetic divergence between populations in the species. The lack of genetic differentiation among groups is most likely due to the combined gene flow from the downstream movement of eggs and larvae with currents and the upstream or downstream migration of adults throughout the distribution. These groups of L. elongata distributed in upper reaches of the Yangtze River should be considered as a single management unit.

Length-weight relationships of four freshwater ornamental fish species from the Brazilian Negro River basin

Summary The present work reports the length–weight relationships (LWR) for four ornamental fish species from the middle Negro River basin, Amazonas, Brazil. The r2 value ranged from 0.810 to 0.941 and values of b varied from 2.346 to 3.442. These results represent the first reference on LWR for all four species, based on FishBase.

Cytogenetic characterisation of the ornamental freshwater fish, Piabucus melanostomus (Iguanodectinae) from Brazilian wetlands and its relation with species of Characidae basal group

The genus Piabucus is the only member of the subfamily Iguanodectinae found in the Pantanal of Mato Grosso State, where it is represented by Piabucus melanostomus. P. melanostomus from the Paraguay and Bento Gomes Rivers of the Pantanal wetlands were analysed using conventional and molecular cytogenetic techniques to cytogenetically characterise the species and broaden the knowledge of the subfamily. The results indicated no sex-related heteromorphisms. The diploid number for the species was 2n = 50 chromosomes, which were divided into six metacentric, eight submetacentric, 24 subtelocentric, and 12 acrocentric with a fundamental number (FN) of 88. Heterochromatin was visualised using the C-banding technique, which showed that it was mainly distributed in the centromeric and pericentromeric region of most chromosomes, but larger blocks were observed on the long arms of large subtelocentric chromosomes (8, 9, 10, 13, and 20 pairs). Nucleolar organising regions (Ag-NOR) were observed in the p-subterminal region of one subtelocentric chromosome pair (9) with a remarkable size polymorphism between homologues in individuals from the Paraguay River, which was confirmed using the FISH technique with 18S rDNA. In this population, in all individuals studied, one of the homologous shows block considerably larger. The karyotype was compared with those of other subfamilies considered basal in Characidae, according to morphological data.

Haematology and plasma chemistry of the red top ice blue mbuna cichlid (Metriaclima greshakei)

Clinical haematology and blood plasma chemistry can be used as a valuable tool to provide substantial diagnostic information for fish. A wide range of parameters can be used to assess nutritional status, digestive function, disease identification, routine metabolic levels, general physiological status and even the assessment and management of wild fish populations. However to evaluate such data accurately, baseline reference intervals for each measurable parameter must be established for the species of fish in question. Baseline data for ornamental fish species are limited, as research is more commonly conducted using commercially cultured fish. Blood samples were collected from sixteen red top ice blue cichlids (Metriaclima greshakei), an ornamental freshwater fish, to describe a range of haematology and plasma chemistry parameters. Since this cichlid is fairly large in comparison with most tropical ornamental fish, two independent blood samples were taken to assess a large range of parameters. No significant differences were noted between sample periods for any parameter. Values obtained for a large number of parameters were similar to those established for other closely related fish species such as tilapia (Oreochromis spp.). In addition to reporting the first set of blood values for M. Greshakei, to our knowledge, this study highlights the possibility of using previously established data for cultured cichlid species in studies with ornamental cichlid fish.

관상어로부터 분리한 Megalocytiviruses에서 나타나는 ORF25 유전자 부위의 반복서열 특성 분석

The presence of ISKNV-like viruses in various freshwater ornamental fish species imported from Asia was confirmed by polymerase chain reaction(PCR) amplification of the ATPase(adenosine triphosphatase) gene. Interestingly, molecular analyses of the Open Reading Frame 25(ORF25) region of these isolates based on the ISKNV(Infectious spleen and kidney necrosis virus) genome revealed the presence of various repetitive sequences. ORF25 repeat sequence length had no effect on cumulative mortality of rock bream Oplegnathus fasciatus challenged with tissue homogenates of infected pearl gourami, Trichogaster leeri; silver gourami, Trichogaster microlepis; blue gourami, or Trichogaster trichopterus. All isolates induce cumulative mortalities after 12 days of infection, confirming that ORF25 polymorphism did not affect the pathogenicity of ornamental fish megalocytiviruses that cross infect rock bream, a seawater fish. Also, no statistically significant differences in spleen index or viral copy number in infected tissues was detected between isolates with varying ORF25 repeat sequence lengths. However, further studies are necessary to fully characterize the functional characteristics of these polymorphisms in megalocytivirus disease in ornamental fishes.

Nodavirus Infection in Freshwater Ornamental Fishes in India: Diagnostic Histopathology and Nested RT-PCR#

Nodavirus Infection in Freshwater Ornamental Fishes in India: Diagnostic Histopathology and Nested RT-PCR#

Nutritional requirements of freshwater ornamental fish: a review

The knowledge of nutritional requirements in ornamental fish species is essential to improve the productive development; however, the nutritional information of these species is scarce and sometimes this information is extrapolated from results obtained from nonornamental fish species. In ornamental fish, a correct formulation of the diet improve the nutrient digestibility and supply the metabolic needs, reducing the maintenance cost and at the same time the water pollution. Inert food such as meal powder, flakes, milk powder, bovine heart and liver, tubifex worms, as well as live food including Artemia sp., rotifers and Moina have been used extensively in ornamental fish feeding with a diverse range of nutritional values and productive properties. In contrast with farmed fish, skin pigmentation is a mandatory characteristic in ornamental fish and the use of dietary supplements with carotenoids is recommended. The aim of this document is to review the specific nutritional requirements which are indispensable to improve economical and productive potential of freshwater ornamental fish. Key words: Aquarium fish, carotenoids, energy, lipids, ornamental fish, protein, vitamins. (Sources: AIMS, CAB).

Biology and invasive potential of the introduced swordtail Xiphophorus hellerii Heckel (Poeciliidae) in Western Australia

Abstract The swordtail Xiphophorus hellerii is a popular ornamental freshwater fish that occurs as an introduced species in the aquatic habitats of at least 31 countries. Although introduced populations are found in other Australian states, the only known Western Australian population occurs in the Irwin River (29°15′S). The biology of X. hellerii in the Irwin River in south‐western Australia is described from four seasonal samples, collected by seine net, between spring 2002 and winter 2003. Pregnant females were collected in all seasonal samples, though juveniles were absent in spring, implying that juvenile mortality during late winter is high. Although mean length of pregnant females (38.7 mm) and mean gonadosomatic index (GSI) (14.7) were similar to reported data for X. hellerii populations in Queensland, mean fecundity was markedly lower in Western Australia, i.e. 34.1, cf. 60.15. Logistic analysis of the percentage of female and male X. hellerii with developing and mature gonads predicted that the length at which 50% of the sexes mature was 30.8 and 31.5 mm SL, respectively. The sex ratios of females to males did not differ statistically from a ratio of 2:1. The diet of all X. hellerii size classes was omnivorous (primarily vegetal matter/algae), although a significant difference was observed between the diet of juveniles and that of the two larger size classes (i.e. juveniles consumed greater quantities of aquatic invertebrates). A melanic polymorphism (i.e. pigmented caudal peduncle and fin) was observed in approximately 5% of X. hellerii collected. If released, the range of X. hellerii is likely to expand in anthropogenically modified habitats in tropical and temperate latitudes of Western Australia. Potential ecological impacts on indigenous fishes may be magnified owing to the depauperate nature of the endemic ichthyofauna including a lack of predators. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Polymorphism in an open reading frame, ORF-2, in the megalocytivirus of freshwater ornamental fishes

We examined the multi-length amplicons by PCR with a single set of primers to a putative open reading frame, the ORF-2 genomic region of megalocytivirus isolates obtained from freshwater ornamental fish. From sequence analysis of the multi-amplicons, we demonstrated the presence of distinct genomic polymorphisms in the ORF-2 region with differing numbers of repetitive element (RE) of 32 aa and 17 aa. SMPV (single major amplicon-producing megalocytiviruses) and MMPV (multiple major amplicon-producing megalocytiviruses) after challenge experiments in two different host species, the pearl gourami ( Trichogaster leeri), the original ornamental species, and rock bream ( Oplegnathus fasciatus), a cross-infective marine species, displayed the same feature of polymorphism in the ORF-2 region as those in the original sample. No significant difference in pathogenicity was found between SMPV and MMPV. Additionally, viral DNA extracted from the infected tissue homogenates incubated even for two days can produce distinct polymorphism in ORF-2 region is implying that each RE-subtype corresponding to each different amplicon is present in the capsid of viral particles rather than in the form of a naked nucleic acid. This is the first report elucidating the presence of various RE subtypes of megalocytivirus and possible simultaneous infection with different RE subtypes of virus in freshwater ornamental fish.

Perubahan Histopatologi Kulit Ikan Koi (Cyprinus carpio) yang Terinfestasi Ichthyophthirius multifiliis Secara Kohabitasi &lt;br&gt;&lt;i&gt;[Skin Histopathology Alteration of Koi (Cyprinus carpio) With Ichthyophthirius multifiliis Infested Accordance Cohabitation]&lt;i&gt;

AbstractKoi (Cyprinus carpio) is one of the most famous freshwater ornamental fish which offers financial advantage. There are a lot of factors which have to be face when we're trying to cultivate or culture Koi, one of those factors is the disease. Parasite which always in freshwater fishes is Ichthyophthirius multifiliis. I. multifiliis penetrated through skin causing destruction ephitelium cells by cilia and by consequent causing a histopathological changing. The objectives of this research was to determine alteration of Koi (Cyprinus carpio) skin histopathology which infested by I. multifiliis through cohabotation. Cohabitation was done during 4 days with mixing 7 fishes infected with white spot disease to 100 healthy fishes. Koi that had been infested observing of pathology changes. And than slicing the skin organ to prepare histopatology slide from 3 sample in every level infestation. To detect the level infestation, parasite was divide into 3 level respectivelly are low level (1-5 parasite/slide), the medium level (6-10 parasites/slide) and the heavy level (more than 11 parasites/slide). Furthermore, damage level determination by histopatology was decided by scoring. Data analyzed with descriptive based on clinical simptom, and than, the skin histopatology which had been attacked was done by scoring. The results would be analyzed statistical with Kruskal Wallis test. If it is show the significant defference, the test would be continued with Z test 5% (Siegel, 1986). The research showed that the fish skin Koi infestation by I. multifiliis there was histopatology changed shaped respectivelly epidermis proliferation, infiltration of inflammation cell and ephithel erosion. Based on histopatological changed skoring caused by I. multifiliis infestation from various infestation grade, there were 62.2% of Koi fish skin was epidermis proliferasi, 73.3% of one was infiltration of inflammation cell and 28.9% ephithel erosion. Water quality measurement showed that temperature and acidity in normal condition, respectively otemperature between 24–26 C dan pH 8.

Carotenoid-enriched microalgal biomass as feed supplement for freshwater ornamentals: albinic form of wels catfish (Silurus glanis)

Experiments were aimed at examining the effect of carotenoid-rich microalgal biomass as feed supplement to increase the colouration of a freshwater ornamental fish species – an albinic form of wels catfish (Silurus glanis). We used four Algadiets (AD 1, AD 2, AD 3, AD 4 – various Algadiets prepared by addition of microalgal biomass to a basal diet) made up of a basal diet supplemented with 25 g kg−1 spray-dried biomass of green algae Scenedesmus, Chlorella, or Haematococcus enriched in carotenoids (12–60 mg kg−1 of feed) for a juvenile fish (yearlings; about 14–25 g and 12–15 cm) in indoor tanks. In 2-month experiments, the fish groups were examined at 20-day intervals. In the treatment groups fed with Algadiets, the specific growth rate and physical condition index (weight/length) increased by 11–58% and 6–26%, respectively, compared to the control (fed on the basal diet). Skin colouration was evaluated from digital images. An intensive yellow or yellow–orange colouration appeared in all Algadiet-fed fish groups because colour saturation increased 1.4–2.4 times within 20–40 days of the trial. A change from an albinic to an intensive ‘golden’ colour was visible as the shorter-wavelength shift from 595–607 to 584–586 nm. These results are economically valuable for albinic catfish breeding, a unique and commercially important species for fisheries in the Czech Republic.

Morphology and distribution of granulomatous inflammation in freshwater ornamental fish infected with mycobacteria

Mycobacteriosis in fish is a chronic progressive ubiquitous disease caused by Mycobacterium marinum, M.gordonae and M.fortuitum in most cases. The aim of this study was to describe the morphology and distribution of lesions in 322 freshwater ornamental fish across 36 species. Granulomatous inflammation was diagnosed by gross examination and histopathology testing in 188 fish (58.4%); acid-fast rods (AFR) were determined in only 96 (51.1%) fish from 19 species after Ziehl-Neelsen staining. The most often affected organs with AFR were the kidney (81.2%), digestive tract (54.1%), liver (48.2%), spleen (45.9%) and skin (21.2%); sporadically, AFR were found in the branchiae (9.4%) and gonads (4.7%). In 14 randomly selected fish originating from four different fish tanks, the distribution of mycobacterial infection was studied by culture examination of the skin, gills, muscle tissue, digestive tract, liver, spleen and kidney. In 12 fish, the species M.marinum, M.gordonae, M.fortuitum, M.triviale, and M.avium subsp. hominissuis (serotypes 6 and 8 and genotype IS901- and IS1245+) were detected; mixed infection caused by different mycobacterial species was documented in five of them.

Parasitic fauna of eight species of ornamental freshwater fish species from the middle Negro River in the Brazilian Amazon Region

Twenty-seven specimens of cardinal tetra Paracheirodon axelrodi, 33 rosy tetra Hyphessobrycon copelandi (Characidae), 28 marbled hatchetfish Carnegiella strigata, 26 blackwing hatchetfish Carnegiella martae (Gasteropelecidae), 27 bodó Ancistrus hoplogenys (Loricariidae), 31 brown pencilfish Nannostomus eques, 38 oneline pencilfish Nannostomus unifasciatus (Lebiasinidae) and 13 angelfish Pterophyllum scalare (Cichlidae) were collected from the middle Negro River, State of Amazonas, Brazil, for parasitological studies. Out of the total of 223 fish examined, 143 (64.1%) were parasitized by at least one parasite species. The highest prevalence rate was for Monogenea (36.7%), followed by Ichthyophthirius multifiliis (Ciliophora) (20.6%), Trichodina spp. (Ciliophora) (4.0%), Piscinoodinium pillulare (Dinoflagellida) (1.3%), Tetrahymena sp. (Ciliophora) (0.89%), and Procamallanus sp. (Nematoda) (0.4%). All eight fish species had Monogenea (Gyrodactylidae and Dactylogyridae) in the gills, but the highest prevalence occurred in P. scalare and the lowest in P. axelrodi and C. strigata. However, the highest mean intensity of Monogenea was found in P. scalare and A. hoplogenys. The protozoan I. multifiliis occurred in the six ornamental fish species examined, but C. strigata and C. martae had higher prevalence and mean intensity. Trichodina spp. were found only in the gills of C. strigata, C. martae and N. eques, and with higher mean intensity in C. strigata. On the other hand, the protozoan P. pilullare was found only in the gills of C. martae. This is the first report of Tetrahymena sp. in Brazil, and it occurred in the gills of C. strigata.

Parasitic fauna of eight species of ornamental freshwater fish species from the middle Negro River in the Brazilian Amazon Region

Twenty-seven specimens of cardinal tetra Paracheirodon axelrodi, 33 rosy tetra Hyphessobrycon copelandi (Characidae), 28 marbled hatchetfish Carnegiella strigata, 26 blackwing hatchetfish Carnegiella martae (Gasteropelecidae), 27 bodó Ancistrus hoplogenys (Loricariidae), 31 brown pencilfish Nannostomus eques, 38 oneline pencilfish Nannostomus unifasciatus (Lebiasinidae) and 13 angelfish Pterophyllum scalare (Cichlidae) were collected from the middle Negro River, State of Amazonas, Brazil, for parasitological studies. Out of the total of 223 fish examined, 143 (64.1%) were parasitized by at least one parasite species. The highest prevalence rate was for Monogenea (36.7%), followed by Ichthyophthirius multifiliis (Ciliophora) (20.6%), Trichodina spp. (Ciliophora) (4.0%), Piscinoodinium pillulare (Dinoflagellida) (1.3%), Tetrahymena sp. (Ciliophora) (0.89%), and Procamallanus sp. (Nematoda) (0.4%). All eight fish species had Monogenea (Gyrodactylidae and Dactylogyridae) in the gills, but the highest prevalence occurred in P. scalare and the lowest in P. axelrodi and C. strigata. However, the highest mean intensity of Monogenea was found in P. scalare and A. hoplogenys. The protozoan I. multifiliis occurred in the six ornamental fish species examined, but C. strigata and C. martae had higher prevalence and mean intensity. Trichodina spp. were found only in the gills of C. strigata, C. martae and N. eques, and with higher mean intensity in C. strigata. On the other hand, the protozoan P. pilullare was found only in the gills of C. martae. This is the first report of Tetrahymena sp. in Brazil, and it occurred in the gills of C. strigata.

DOMESTICATION OF FRESHWATER PUFFER FISH OR BUNTAL (Tetraodon palembangensis)

The Research Institute for Freshwater Ornamental Fish Culture has been conducting domestication research since 2004 on adult freshwater puffer fish or buntal broodstock in which the fish were reared in aquaria and fed with small feed fish teri (anchovy) and earthworm (Lumbricus sp.). The domestication of freshwater puffer fish or buntal has resulted in successful environmental adaptation and reproductive ability of the fish and further rearing of its fry. The adaptive ability was indicated by its high survival rate, good growth and development, and the reproductive success in spawning, egg production, hatching as well as growing of the larvae to fry stages. The mature gonad stage of the fish was reached at an average body weight of 150 g with a reproductive period of 5 months. The spawning occurred naturally and the eggs were gradually released at interval periods of 14—18 days with egg production rates of 1,000—1,900 eggs per spawning. The highest egg fertilization rate was 96%, with the highest egg hatching rate of 78.6%. Hatching process took place on the 6th to 13th days after spawning process. The surviving larvae began feeding filtered natural foods Moina sp. on the 3rd day up to the 6th day, whereas unfiltered Moina sp. was given from the 7th to 14th days. The fish were fed the live feed Culex sp. from the 15th to 30th days. In the following period the fish was fed earthworm and small feed fish teri (anchovy).

Transmission of iridovirus from freshwater ornamental fish (pearl gourami) to marine fish (rock bream)

Freshwater pearl gourami Trichogaster leeri and seawater rock bream Oplegnathus fasciatus infected by the iridoviruses PGIV-SP and IVS-1 were carrying similar numbers of viral particles (2.52 x 10(8) and 2.46 x 10(8) viral genome copies mg(-1) spleen tissue, respectively). The viral genome copy number for both iridoviruses decreased much faster in seawater than in freshwater, reaching a concentration of less than 0.5%, versus 26 to 54% in freshwater, after 4 d of incubation at 25 degrees C. The decrease in copy number altered the infectivity of the viruses, as reflected by the decreased cumulative mortality of rock bream injected intraperitoneally with the incubated iridoviruses. Moreover, uninfected rock bream cohabitated with PGIV-SP-challenged rock bream showed 100% cumulative mortality; a similar experiment using IVS-1 had the same result, implying the potential for iridoviral transmission from freshwater ornamental fish to marine fish even in a marine environment. Of 58 outwardly healthy marine fish groups collected from various markets, 2 rock bream groups and 1 sea perch group Lateolabrax sp. tested positive for PGIV-SP by 2-step polymerase chain reaction (PCR). Thus, PGIV-SP from freshwater ornamental fish may have crossed both environmental and species barriers to infect marine fish such as rock bream.