• Journal of fish pathology
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• v.17 no.3
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• pp.179-189
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• 2004

Morphological structure and sporogenesis of myxosporean parasite, Parvicapsula anisocaudata from cultured olive flounder, Paralichthys olivaceus were examined by light and transmission electron microscopies. Numerous round early stages, spindle-shaped disporic or monosporic pseudoplasmodia, asymmetrical thin-walled mature spores were found inthe lumen of renal tubule and urinary bladder. Long pseudopodia or short projections from cytoplasm of pseudoplasmodia make the parasite attach firmly to host tissues. Spore development was mono- or disporous with no pansporoblast formation. Sporoplasmic cell was partially surrounded by two capsulogenic cells, and capsulogenic cells were enveloped by two flattened valvogenic cells. Capsulogenesis and valvogenesis followed general patterns seen in that of other myxosporean.

• Journal of fish pathology
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• v.10 no.2
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• pp.137-142
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• 1997

A monogenean gill parasite, Prosomicrocotyla gotoi, and a digenean intestinal fluke. Opecoelus sphaericus, were found from greenilngs (Hexagrammos otakii) captured at the Korean southern sea. P. gotoi was characterized by having two separated frills of opisthaptor and distinguished from P. chirii in testis and clamp numbers. O. sphaericus had three pairs of finger-like marginal appendages on the ventral sucker and the parasite was distinguished from O. nipponicus in the location pattern of testes. These two helminth species were the first recording species in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.611-621
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• 2014

A nationwide survey was conducted to study the rate of Kudoa septempunctata parasitization in cultured olive flounder, Paralichthys olivaceus, in Korea in 2013. Of 1107 olive flounder sampled randomly from 89 culture farms in five different regions in Korea, K. septempunctata was detected only in Jeju, where 10 of 318 fish (3.14%) were PCR positive, with genomic concentrations of $4.67{\times}10^5$ to $1.48{\times}10^{11}$ rDNA copies/g by real-time PCR. Of the ten Kudoapositive fish, K. septempunctata spores with 5-7 polar capsules were detected only in four fish. No samples of K. septempunctata were detected in olive flounder from the other regions surveyed. Furthermore, K. septempunctata was not detected in 326 samples of olive flounder seeds sampled from 39 hatcheries in seven different regions in Korea. Therefore, the parasite infection is restricted to Jeju and K. septempunctata infection is not spread from hatcheries.

• 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.11 no.2
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• pp.119-127
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• 1998

Two species of the parasitc copepods, Clavellopsis hugu (Lemaeopodidae; Siphonostomatoida) and Taeniacanthus yamagutii (Taeniacanthidae; Poecilostomatoida) from cultured Korean fish, Takifugu obscurus, is described and reported for the first time in Korea. The parasite was recovered from the buccal cavity, nose and skin. Clavellopsis hugu is easily identified by the body shape, 2nd antenna, mandible and 2nd maxillae. In female, cephalothorax flexed dorsally, second antenna biramose, mandible with serrate blade, second maxillae completely fused at base of cephalothorax. In male, cephalothorax and trunk fused into an ovoid, two pairs of maxillipeds chelate. The most distinctive features of Taeniacanthus yamagutii are terminal process of second maxilla stout, maxilliped claw with conspicuous digitiform process at base and a setiform element at the tip of each exopod spine of legs 2-4. Both parasitic copepod species are new to the Korean fauna. The korean fish, Takifugu obscurus should be considered as an additional host of this species because these parasite were recovered from the western coast of Korea (Boryung Hatchery).

• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.68-71
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• 1998

The egg structure and shape of the skin parasite, Entobdella hippoglossi from the Atlantic halibut, Hippoglossus hippoglossus was examined using scanning electronic microscope. The newly produced eggs of E. hippoglossi were yellowish in color and tetrahedral in shape. The eggs were entwined together in a complicated chain-like fashion by a long filament. The appendage showed the presence of buoy-like structures. The buoy-like structures on the appendage of the eggs of E. hippoglossi in the present study were totally different from other sticky droplets. It is suggested that these structures are not sticky droplets but buoys for floating eggs which have entwined together on the bottom of the sea. It seems that these buoy-like structures may be needed for preventing the eggs from being covered by mud or particles and thus maintaining the eggs in an oxygenated environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.248-253
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• 2018

Freshwater farms are primarily located adjacent to rivers and lakes, facilitating the introduction and spread of pathogens into natural systems. Therefore, it is necessary to continuously monitor natural aquatic organisms, the breeding environment, and infection rates by pathogenic organisms. Fish and crustaceans were sampled 4 times in the Geum River estuary in 2016. The samples were analyzed for the presence of pathogens for reportable communicable diseases, including KHVD (koi herpesvirus disease), SVC (spring viraemia of carp), EUS (epizootic ulcerative syndrome) and WSD (white spot disease); parasite abundance was also examined. The dominant fish species were deep body bitterling Acanthorhodes macropterus (21.4%), followed by skygager Erythroculter erythropterus (12.7%). For crustaceans, Palaemon paucidens and Chinese mitten crab Eriocheir sinensis were dominant. Sixty fish and 36 crustacean species were examined for reportable communicable diseases. When using a specific primer set for each disease, PCR analysis did not detect any reportable communicable diseases in the samples. Some instances of Dactylogyrus, copepods, nematodes and metacercaria were detected. However, the PCR results indicated that the metacercaria were not Clonorchis sinensis.

• 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.

• Animal Systematics, Evolution and Diversity
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• v.22 no.2
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• pp.121-125
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• 2006

Ergasilus zacconis (Yamaguti, 1936), the copepod parasite originally named as Pseudergasilus zaconnis, is redescribed based on the specimens newly collected from the freshwater fish Zacco platypus (Temminck and Schlegel) from Japan. Some errors appearing in the original description are emended. An explanation for the generic position of this species is given.

• Journal of fish pathology
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• v.15 no.3
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• pp.117-119
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• 2002

A kind of leeches, Trachelobdella sp was detected on the inside surface of the opercle of wild crucian carp, Carassius cuvieri (21.5 cm in length and 238.5 g in weight) at a reservoir for agriculture in ChungNam Province of Korea in March, 2002. Two or three round transparent spots on the opercle could be easily detected. The fish also showed severe anemia and dorsally darking in the gill lamellae. The parasites was identified as Trachelobdella sp. on the basis of morphological characteristics such as suckers, body segmentation and lateral diverticula. As the parasites fed on host blood after attaching on the inside surface of the opercle by means of the posterior sucker, they caused severe anemia and petechial haemorrhge on the gill of infested fish. Heavy infestation of the parasite resulted in dath of fish because of large amount of blood loss.