• Journal of fish pathology
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• v.3 no.1
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• pp.11-19
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• 1990

Yellow tail (Seriola quinqueradiata) infected by Pasteurella piscicida have been occurred to mass mortality without showing apparent surface lesions in cage culture farms. In this case, it is necessary to consider countermeasure by rapid diagnosis of infected fish. The purpose of the present study was to investigate usefulness of the direct fluorescent antibody technique(FAT) for rapid diagnosis of pseudotuberclosis of cultured yellowtail caused by P. piscicida. Antibody produced by inoculating rabbit with formalin killed pseudotuberclosis bacteria antigen(strain KNP-2). Immunoglobulin-G(IgG) was purified from antisera by DEAE-cellulose column chromatography and conjugate with fluorescein isothiocyanate. Fluorescein-labeled antisera was purified by sephadex G-25 gel column chromatography. The fluorescein/protein molar ratio of labeled antisera was determined as 8.8-9.5. Diagnosis of cultured yellowtail was examined in cage culture farms which located in Tongyung, kyungnam from July to October 1990. The causative bacteria of pseudotuberclosis could be detected within two hours after the specimens were transferred to the laboratory for FAT, and it showed that FAT could be adapted as a rapid and accurate diagnostic method of pseudotuberclosis in yellowtail.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.411-419
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• 2018

This study investigated the survival rates and physiological responses of Korean rockfish, Sebastes schlegeli, in live fish containers ($8^{\circ}C$, 33 psu) for 18 days. The survival rate was 99% and 97% in the control and experimental groups, respectively. Hematocrit and hemoglobin did not differ significantly between the control and experimental groups. Glucose and cortisol rose immediately on the first day of containment, but both gradually normalized. Aspartate aminotransferase and alanine aminotransferase did not differ significantly between the two groups after recovery. $NH_3$ continued to rise after the first day, but decreased to a level not significantly different from that of the control group during the recovery period. Plasma ions and osmolality did not change abnormally. The hemocyte population was not significantly different from that of the control. The ratios of apoptotic and necrotic cells indicated no specific variation in hemocyte viability. The histological changes in the skin and gills were not significantly different from those seen in the control. The experimental data obtained in this study suggest that live fish containers may be used to transport Korean rockfish without significantly affecting their physiology or survival.

• Journal of fish pathology
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• v.12 no.1
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• pp.56-62
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• 1999

Since 1998, mass mortality of the Japanese flounder has widely occurred in the south and west coastal area of Korea. A new serotype birnavirus was isolated during the investigation of the cause of the disease. By the electromicroscopic examination, the isolated virus particles appeared hexagonal and unenveloped with an average diameter 52 to 56 nm. Birnavirus specific fragment was amplified by RT-PCR. High yield of virus (10.3 to 10.8 log $TCID_{50}/ml$) was produced in CHSE-214. RTG-2 and RTE-2 cells. Typical birnavirus CPE was observed in these cells. On the contrary, the virus CPE was not shown in the FHM and EPC cells. By a cross-neutralization test with IPNV Ab, IPNV Sp, IPNV VR-299 and MBV Y6, the isolated virus was closely related to marine birnavirus (MBV).

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.731-737
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• 2016

To understand the characteristics and strength of the cold water that has caused damage to marine-culturing farms around Guryongpo, in the southwestern part of Korea, surface and water column temperatures were collected from temperature loggers deployed at a sea squirt farm during August-November 2007 and from a Real-time Information System for Aquaculture environment operated by NIFS (National Institute of Fisheries Science) during July-August 2015 and 2016. During the study period, surface temperature at Guryongpo decreased sharply when south/southwestern winds prevailed (the 18-26th of August and 20-22nd of September 2007 and the 13-15th of July 2015) as a result of upwelling. However, the deep-water (20-30m) temperature increased during periods of strong north/northeasterly winds (the 5-7th and 16-18th of September 2007) as a result of downwelling. Among the cold water events that occurred at Guryongpo, the mass death of cultured fish followed strong cold water events (surface temperatures below $10^{\circ}C$) that were caused by more than two days of successive south/southeastern winds with maximum speeds higher than 5 m/s. A Cold Water Index (CWI) was defined and calculated using maximum wind speed and direction as measured daily at Pohang Meteorological Observatory. When the average CWI over two days ($CWI_{2d}$) was higher than 100, mass fish mortality occurred. The four-day average CWI ($CWI_{4d}$) showed a high negative correlation with surface temperature from July-August in the Guryongpo area ($R^2=0.5$), suggesting that CWI is a good index for predicting strong cold water events and massive mortality. In October 2007, the sea temperature at a depth of 30 m showed a high fluctuation that ranged from $7-23^{\circ}C$, with frequency and spectrum coinciding with tidal levels at Ulsan, affected by the North Korean Cold Current. If temperature variations at the depth of fish cages also regularly fluctuate within this range, damage may be caused to the Guryongpo fish industry. More studies are needed to focus on this phenomenon.

• Journal of Aquaculture
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• v.21 no.4
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• pp.265-271
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• 2008

Upper temperature tolerance of the turbot Scophthalmus maxim us, one of the popular aquaculture species in European community and China, was evaluated in terms of survival and growth at $20^{\circ}C$, $23^{\circ}C$, $26^{\circ}C$, or $29^{\circ}C$. Best growth was achieved at temperature $20^{\circ}C$ in this experiments. The fish exposed to $20^{\circ}C$ or $23^{\circ}C$ were comparable in survival, condition factor and feed conversion efficiency reminiscent of the latter temperature to be agreeable for the fish. The temperature over $23^{\circ}C$ appeared to be the temperatures beyond the fish can tolerate. For instance, the fish exposed to 26 showed mortality of 60.9% by day 60; none of the fish exposed to $29^{\circ}C$ survived beyond day 7. Culture densities between 80 and $200\;fish/m^2$ did not influence the survival, growth, condition factor and specific growth rate of the fish. The final production of the culture density experiment was $10\;kg/m^2$ on average. These results imply that the location where water temperature remains lower than $25^{\circ}C$ during summer can be a candidate site for the turbot aquaculture.

• Journal of fish pathology
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• v.9 no.1
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• pp.1-9
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• 1996

Many encysted metacercariae of Clinostomum complanatum(Rudolphi, 1814) were found in the flesh near the skin of goldfish(Carassius auratus) sultured at a fish farm in Chonbuk Province, Korea, in the summer of 1995. The mortality reached about 7% from July 10 to August 20. Encysted and excysted metacercariae were$700\sim877{\times}700\sim775{\mu}m$ and $2.4\sim5.5{\times}0.7\sim1.37{\mu}m$ in size, respectively. The parasites looked yellowish due to the yellow particulate matter in the intestine. Of 276 fish examined, 234(84.8%) were infected with a mean intensity of 216.6(range 1~1.214) parasites. Fish of 2.0~2.5 cm in body length were most frequently(94.3%) infected but those of 3.1~3.5 cm were the least infected(75.27%). The isthmus was most heavily infected. There was no difference in prevalence between two forms of goldfish, Gyariko an Ryugum. The sites of infection were swollen and recognized as yellow spots of 0.4~0.8 mm in diameter. Fish infected with more than 200 metacercariae became moribund with listless swimming and finally died.

• Journal of fish pathology
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• v.24 no.2
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• pp.161-166
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• 2011

The metacercariae of Clinostomum complanatum (Rudolphi, 1814) were isolated in the whole body muscle of wild freshwater fish, spotted barbel gudgeon (Squalidus multimaculatus Rosoya et Jeon) from the local river in Yeongdeok, Gyeongsangbuk-do, Korea. The infected fish with bumpy body surface by "yellow grub" showed erratic swimming behavior and some fish were died. The isolated excysted metacercariae were tongue shaped and 2.85~5.89 mm ${\times}$ 0.8~1.99 mm in size. 1~98 metacercariae were isolated in individual fish and mean infection intensity was 25. All examined adult spotted barbel gudgeon sizing 7 cm in body length were infected. This is the first report of disease outbreak and mortality caused by C. complanatum infection in wild freshwater fish in Korea.

• Journal of fish pathology
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• v.13 no.1
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• pp.37-44
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• 2000

CT(Sodium N-chloro-para toluenesulfonamide, Chloramine-T) known to be a strong oxidative agent was investigated to use as a candidate of disinfectant in the marine aquaculture industry by the analysis of the bactericidal activity against different aquatic microorganisms. One hundred percent mortality appeared at and above 16 ppm CT in sea water in flounder, the predominant species in the marine aquaculture of Korea, when exposed for 48hr. However, bactericidal activity was appeared to be very effective, and all different species of the fish pathogenic bacteria exposed to CT of less than 2 ppm in sea water were dead within 15 min. It allowed us to confirm that CT could be a very effective disinfectant to protect the spread of fish pathogenic bacteria derived from diseased fish or sea water in marine aquaculture. High concentration(10 ppm) with longer exposing time(24 hrs) was required for the algicidal activity of CT, at which concentration might induce the acute toxicity against fish, however, restricted the expanded use of CT for the elimination of zooplanktons at phytoplanktons in marine farms. Moreover the bactericidal activity of CT inhibited almost completely in the present of more than 10 ppm of organic materials pointed out that quality of the culturing sea water should be considered carefully for the application CT to the aquatic farms as a therapeutic agent.

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.62-65
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• 2010

Arowana (Scleropages formosus) is the most valuable group of ornamental fishes and very much in demand in the ornamental fish trade and commands high price ranging from hundreds to thousands of dollars per fish. In this paper, we described a case of mortality of arowana from a private aquarium in Korea. A bacterial pathogen from fish organs (brain, kidney, liver) was cultured, identified and confirmed using Vitek System 2, API 20E test, multiplex PCR and 16S rRNA gene sequencing. The morphological and biochemical properties of the bacterium isolated from the brain, kidney and liver of the fish were similar to Aeromonas sobria. Positive amplification products using the multiplex PCR assay for detection of A. sobria were obtained from these organs. The 16S rRNA gene of the isolates from fish was identical and exhibited 100% sequence similarity with A. sobria (AY987762.1) strain available from GenBank. This bacterium contained hemolysin gene, a virulence factor that plays an important role in outbreaks of disease and is pathogenic to humans as well as in fish. Although this opportunistic bacterium was isolated from a fish without any external symptoms, this pathogen may act as a reservoir and enhance chances of zoonosis to human such as during handling.

• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.207-211
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• 2019

Mass mortality in commercially cultured Amur catfish (Silurus asotus), showing symptoms of dermal ulcerations, occurred on a private farm in Mar 2019 in Korea. β-hemolytic bacteria were isolated from the ulcers and kidneys of the fish and identified as Aeromonas veronii. The isolate was resistant to tetracycline and possessed cytotoxic heat-labile enterotoxin (aerolysin/hemolysin). We investigated the genetic determinants associated with tetracycline resistance, and the isolate has been confirmed to simultaneously possess tetA and tetE genes. This is the first report on the occurrence of tetracycline-resistant A. veronii infection related to mass mortality in commercially cultured Amur catfish in Korea.