• Journal of fish pathology
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• v.13 no.2
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• pp.75-86
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• 2000

Monogeneans(Phylum Platyhelminthes) have been known as common parasites onto the skin and gills of cultured freshwater fishes. Infestation with these parasites result in a great loss in aquaculture industry. Some classification studies on these parasites have mostly been conducted in Japan but rarely in Korea. For the purpose of classifying monogenean parasites infesting two Korean freshwater fishes, eel (Anguilla japonica) and catfish(Parasilurus asotus), samples captured from March 1998 to April 2000 were examined. Here we report for the first time in Korea that four different species of monogeneans are identified: Pseudodactylogyrus bini and P. anguillae in eels; Ancylodiscoides infundibulovagina and Ancylodiscoides sp. in catfish.

• Journal of fish pathology
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• v.13 no.2
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• pp.87-96
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• 2000

Monogeneans(Phylum Platyhelminthes) have been known as common parasites onto the skin and gills of cultured freshwater fishes. Infestation with these parasites result in a great loss in aquaculture industry. Some classification studies on these parasites have mostly been conducted in Japan but rarely in Korea. For the purpose of classifying monogenean parasites infesting two Korean freshwater fishes, carp(Cyprinus carpio) and loach(Misgurnus anguillicaudatus), samples captured from March 1998 to April 2000 were examined. Here we report that three different species of Monogeneans, Diplozoon nipponicum, Dactylogyrus extensus from carp and Gyrodactylus paralatus from loach, respectively. Of these the latter two parasites have never been identified in Korea.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.145-146
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• 2001

Despite a variety of development in fish farming during the last decades, fish diseases by bacteria, virus, and parasites are still major problems in aquaculture. Aquaculture of Hounder fish is widely performed around Korea as well as Jeju island, due to relatively stable seed production, short farming period, and a higher value in market. However, intensive feeding and environmental pollution in aquacutural farm act as a great limiting factor in economic aspect. (omitted)

• Parasites, Hosts and Diseases
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• v.61 no.3
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• pp.332-337
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• 2023

Infestations of parasites, particularly those caused by copepods and monogeneans, are a major hindrance to aquaculture and have a big negative economic impact. Sebastes schlegelii, a farmed Korean rockfish, is particularly prone to copepods and monogeneans. This study comprehended how parasitic copepods and rockfish from a farm in Tongyeong-si, Gyeongsangnam-do, Korea, are related to the monogenean trematode Microcotyle sebastis. Our research revealed that monogeneans predominated, with a rate of 98.4% and an average infection intensity of 7 per infected fish. With an average infection intensity of 4 per sick fish, the infection rate for parasitic copepods was equally considerable, coming in at 91.7%. The high co-infection rate of both parasite families, at 90.8%, is noteworthy. Furthermore, Lepeophtheirus elegans and Peniculus truncatus, 2 parasitic copepod species, were discovered to have M. sebastis eggs attached to their bodies. This demonstrates a connection between parasitic copepod infestations in farmed Korean rockfish and the monogenean trematode M. sebastis. These discoveries highlight the necessity for creating more potent parasite control methods for the aquaculture sector and shed light on the intricate relationships between various parasite species.

• Journal of fish pathology
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• v.36 no.2
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• pp.403-408
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• 2023

Mullet is an important marine aquaculture fish species in Korea, with a total of 7,237 tons produced as of 2022, making it the 5th most produced marine aquaculture fish species. In this study, ectoparasites presumed to be isopods were discovered in the fins of farmed flathead grey mullet (average weight 550 g), and the characteristics of the parasites were confirmed. The length of the parasite was 5 to 18 mm, and 3 to 7 parasites were infected per fish. To analyze the characteristics of the parasites, molecular biological identification and phylogenetic analysis were performed using the cytochrome c oxidase subunit I (COI) gene, and it was confirmed to be most closely related to Nerocila japonica in the Cymothoidae family. To confirm the parasite control effect, a direct exposure drug sensitivity test was conducted on five types of aquatic drugs and fresh water, trichlorfon was confirmed to be effective.

• Journal of fish pathology
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• v.34 no.2
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• pp.161-168
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• 2021

Quantitative analysis of myxosporean parasites (Enteromyxum leei and Parvicapsula anisocaudata) were performed using real-time PCR on the internal organs (head kidney, body kidney, intestine, spleen, brain, liver, heart, muscle, blood, and eye) of emaciated Paralichthys olivaceus from farm-A. The highest DNA copy number of E. leei was shown in the intestine (1.3 × 10⁸ copies/mg tissue) of emaciatied P. olivaceus and DNA copy number in the other internal organs (1.3 × 10³~4.6 × 10⁵ copies/mg tissue) showed lower than in intestine. From the result of real-time PCR for P. anisocaudata, it was considered mildly infected, due to the low DNA copy numbers of the head kidney (1.3 × 10³ copies/mg tissue) and body kidney (9.1 × 10³ copies/mg tissue). In order to investigate whether myxosporean parasites can be detected in a non-invasive way, quantitative analysis of E. leei and P. anisocaudata from rearing water of three farms were performed by real-time PCR. The DNA copy number of E. leei from rearing water of farm-A and farm-B were 8 × 10⁴ and 5 × 10⁵ copies/L, respectively. However, it was not detected in farm-C. For P. anisocaudata from rearing water, farm-A, farm-B and farm-C showed 0, 2.0 × 10⁶ and 5.1 × 10⁶ copies/L, respectively.

• Journal of fish pathology
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• v.29 no.1
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• pp.1-5
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• 2016

Isopods are parasitic crustaceans that pose serious threat to fisheries. Several studies have tried to explore the host-pathogen relationship between marine fishes and isopods. The present study aims to understanding the secondary infections in marine fishes pertaining to isopods. To assess the secondary infection in infected fishes, parasite infested and healthy tissues of fishes were collected. The samples were subjected to standard microbiological procedure to identify the presence of pathogenic bacteria and fungi. Our results showed the branchial region had the higher microbial load of non-sporulating cenocytic fungi in infected fishes. Moreover, fungal strains isolated from the parasitic lesion confirmed that the parasitation and body lesion facilitates the entry of several pathogenic microbes at the damaged host tissue. More over the immune regulation of fish fights back by producing minute cysts, trying to encapsulate the growing fungus. But this may eventually lead to systemic infestation and death of the fish.

• Parasites, Hosts and Diseases
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• v.52 no.1
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• pp.9-19
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• 2014

Anisakis spp. (Nematoda: Anisakidae) parasitize a wide range of marine animals, mammals serving as the definitive host and different fish species as intermediate or paratenic hosts. In this study, 18 fish species were investigated for Anisakis infection. Katsuwonus pelamis, Euthynnus affinis, Caranx sp., and Auxis thazard were infected with high prevalence of Anisakis type I, while Cephalopholis cyanostigma and Rastrelliger kanagurta revealed low prevalence. The mean intensity of Anisakis larvae in K. pelamis and A. thazard was 49.7 and 5.6, respectively. A total of 73 Anisakis type I larvae collected from K. pelamis and A. thazard were all identified as Anisakis typica by PCR-RFLP analysis. Five specimens of Anisakis from K. pelamis and 15 specimens from A. thazard were sequenced using ITS1-5.8S-ITS2 region and 6 specimens from A. thazard and 4 specimens from K. pelamis were sequenced in mtDNA cox2 region. Alignments of the samples in the ITS region showed 2 patterns of nucleotides. The first pattern (genotype) of Anisakis from A. thazard had 100% similarity with adult A. typica from dolphins from USA, whereas the second genotype from A. thazard and K. pelamis had 4 base pairs different in ITS1 region with adult A. typica from USA. In the mtDNA cox2 regions, Anisakis type I specimens from A. thazard and K. pelamis showed similarity range from 94% to 99% with A. typica AB517571/DQ116427. The difference of 4 bp nucleotides in ITS1 regions and divergence into 2 subgroups in mtDNA cox2 indicating the existence of A. typica sibling species in the Makassar Strait.

• Journal of Species Research
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• v.8 no.4
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• pp.373-379
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• 2019

Two parasitic copepods, poecilostomatoid Colobomatus mylionus Fukui, 1965 and siphonostomatoid Clavellisa chinensis ($Y{\ddot{u}}$, 1933), were reported for the first time from Korea and redescribed based on the females collected from the marine fish of Korean waters. The C. mylionus was collected from the blackhead seabream, Acanthopagrus schelegelii(Bleeker). Colobomatus mylionus had been frequently reorded from marine teleost fishes from of Eden, Newcastle, Brisbane, Yelloon, and Point Sampson. The second record was C. chinensis redescribed based on the speciemens collected from the gills of a Japanese grenadier anchovy, Coilia nasus Temminck and Schlegel. Some differences were observed between the orginal description of known specimens examined in this study, these differences do not warrant a change in the taxonomic staus of the two species. The attachment site of all two copepods reported from Korea were the cephalic sensory canals and gills.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.112-120
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• 2007

This paper reviews the use of parasites as 'biological tags' for studying stock analysis of salmonid fishes. Numerous definitions of stock concepts exist, but most of them essentially define a group of fish as having similar biological characteristics and being self-reproducing as stocks. It is important to manage fish stocks for human consumption and sustainable production and especially for salmonid fishes. Because these fry are considered as each country's property, it is necessary to identify and discriminate each fish stock in the open sea. Methods of separating fish stocks are very diverse. Artificial tags, parasites, otoliths scales and genetic characters have been used for stock analysis and each method has advantages and disadvantages. Of these parasites can be good biological tags because they are applied by nature at no cost. Parasites can be infected with susceptible host fishes when they enter into certain areas. Then if they move to the outside and are caught researchers can infer that the fish had been in the endemic area for a period of time during their life. Hence the host fish can be considered as naturally 'tagged' by parasites. However, if they do not pass the parasites-endemic. area, they will harbour no parasites. Therefore, researchers can discriminate each fish stocks and trace their migration routes with these biological tags. In this paper, several examples on the use of parasites as biological tags for studying salmonids, as well as other species, are listed. The advantages and limitations of parasites as biological tags are also discussed. Chum salmon (Oncorhynchus keta), the main salmonid species migrating to Korea, is distributed all around the North Pacific. Korean chum salmon are generally thought to move to the Sea of Okhotsk, the western North Pacific and the Bering Sea. However, there is no clear information on the distribution and migration pathways of Korean chum salmon, and no markers exist for separating them from others yet. Recent Korean chum salmon stock analysis including parasites information are mentioned.