• Journal of Marine Life Science
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• v.1 no.1
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• pp.18-24
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• 2016

Since April 2012, doctor fish in the breeding tank and in the quarantine tank in Hanwha Aquaplanet Yeosu Aquarium have been dying, accompanied by diffuse bleeding around the mouth, in the chin, and at the bottom of the abdomen. In this study, the cause of death would be examined through the bacteriological study of doctor fish and the rearing water quality in the aquarium. The water quality and the bacterial counts of the rearing water in the exhibit tank and in the quarantine tank were analyzed once a week, starting from August to November 2014. Water quality was measured based on the following data: temperature was in the range of 24.5~26.8℃, pH at 6.77~7.94, DO at 6.15~8.61 ppm, ammonia at 0~0.93 ppm, nitrite at 0.009~0.075 ppm, and nitrate at 1.1~40.9 ppm. Studies revealed that the differences in these water quality factors were not related to the death of doctor fish. Bacterial counts in the rearing waters of Garra rufa slightly increased to 10³~10⁴ CFU/ml, just before the death of the doctor fish. Twelve strains of bacteria were isolated from the dead fish and rearing waters. The isolates were identified as Aeromonas veronii, Citrobacter freundii, Pseudorhodoferax aquiterrae, Shewanella putrefaciens, and Vibrio anguillarum on the basis of 16S rRNA gene sequences. The most dominant species was C. freundii, which showed medium sensitivity to florfenicol and norfloxacin, and was resistant to amoxacillin, doxycycline, oxytetracycline, tetracycline, and trimethoprim. Ten isolates were confirmed to be pathogenic to the doctor fish. Doctor fish infected with C. freundii and S. putrefaciens showed high mortality in the experimental groups. These results indicate that the variation in bacterial numbers in the rearing water was related to the death of doctor fish. C. freundii and S. putrefaciens were directly implicated in causing the death of doctor fish in the aquarium.

• Korean Journal of Bronchoesophagology
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• v.1 no.1
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• pp.164-167
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• 1995

Foreign holies in the upper aerodigestive tract are an important cause of morbity and mortality in older adults and children under 3 years of age. Fish and chicken bones are the usual foreign bodies lodged in the hypopharynx, and most of them lodge In the lower pole of a tonsil, at the base of the tongue, at the lateral wall of the pharynx, or in a vallecula. Recently, the authors experienced a case of aspiration pneumonia caused by chronic local inflammatory reaction of the posterior wall of the hypopharynx originated from a special foreign body.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.26-33
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• 2009

This experiment was conducted to examine the utilization of added dietary selenium (Se) as an immune stimulant in juvenile olive flounder, Paralichthys olivaceus. Fish averaging $4.0{\pm}0.1\;g$ ($mean{\pm}SD$) were fed one of seven semi-purified diets containing 0.56, 1.07, 2.86, 4.56, 43.15, 90.71, or 161.74 mg of Se/kg ($Se_{0.56}$, $Se_{1.07}$, $Se_{2.86}$, $Se_{4.56}$, $Se_{43.2}$, $Se_{90.7}$ and $Se_{161.7}$, respectively) for 12 weeks, respectively. At the end of the feeding trial, the fish fed diets containing more than 43.2 mg of Se/kg showed above 90% mortality. There were no significant differences in weight gain, feed efficiency, specific growth rate, protein efficiency ratio, or hematological characteristics among the fish fed the $Se_{0.56}$, $Se_{l.07}$, $Se_{2.86}$, and $Se_{4.56}$ diets. Se concentrations of the gill, kidney, muscle and liver tissues occurred in dose-dependent manners. Alternative complement pathway activation and the chemiluminescene responses of the fish fed the $Se_{1.07}$ diet were significantly higher than those of the fish fed the other diets (P<0.05). These results indicate that the optimum dietary supplementation level of Selenium as selenoyeast could be 1.07 mg of Se/kg based on the non-specific immune responses of juvenile oilve flounder, Paralichthys olivaceus.

• Journal of fish pathology
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• v.22 no.1
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• pp.23-33
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• 2009

Vibrio harveyi was a significant pathogenic agent and cause a high mortality of cultured fish and shrimp in the aquaculture industry. In this study, we have investigated biochemical, physiological, serological and immunological characteristics of V. harveyi isolated from marine cultured fish. The phenotypes of V. harveyi were differentiated with their own biochemical characteristics and colors of colony on the TCBS agar. V. harveyi were classified into more than four serogroups by agglutination test. Most isolates were classified into a group A which is categorized with the same band pattern generated by western blotting. Group A was characterized by a major protein, which is ranged from 26 and 34 kDa in size, and has a virulence to oliver flounder more than reference strain KCCM40866. Oliver flounders vaccined with FKC of V. harveyi C05011 were highly resistant to infection by other strains of group A.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.634-643
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• 2021

Han In-jin (Artemisia iwayomogi Kitamura) and Cham Dang-gwi (Angelica gigas Nakai) exhibit antibacterial, antiparasitic, antifungal, and antiviral properties in vitro. In this study, mixture of the extracts of these two medicinal plants was absorbed on pellets. Thereafter, these pellets were fed to olive flounder Paralichthys olivaceus for 12 weeks at laboratory (1^st experiment) and 24 weeks at field test (2^nd experiment), and the immune activity and disease resistance properties of the extracts were examined. It was observed that lysozyme activities of plasma, spleen, and kidney improved after 12 weeks. Furthermore, when the olive flounders were artificially infected with bacterial pathogens, their cumulative mortality decreased in the group that was fed the extracts for 12 weeks compared to that in control group, and the relative percent survival also improved. This study concluded that mixture of Han In-jin and Cham Dang-gwi extracts provides disease resistance in vivo.

• Journal of fish pathology
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• v.35 no.2
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• pp.225-230
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• 2022

Viral hemorrhagic septicemia (VHS) is one of the most serious viral diseases affecting farmed olive flounder (Paralichthys olivaceus) in Asian countries. VHS, caused by viral hemorrhagic septicemia virus (VHSV), occurs in over 80 different cultured and wild fish species worldwide. Our previous study demonstrated that VHSV infection can be restricted by adjusting the water temperature to over 17℃ from the host optima. We confirmed that the effective VHSV immersion vaccine treatment was a tissue culture infection dose (TCID) of 10^5.5 TCID₅₀/mL at 17℃. However, the safety of live VHSV immersion vaccines remains unclear. The objectives of this study were to 1) demonstrate the safety of the live VHSV immersion vaccine under co-habitant conditions and 2) estimate the pathogenicity of VHSV in live VHSV-vaccinated flounder at 10℃. No mortality was observed in olive flounder treated with the live VHSV immersion vaccine, and the vaccinated flounder challenged with VHSV did not transfer VHSV to naïve fish at 10℃ through cohabitation. VHSV titration was below the detection limit (< 1.3 log TCID₅₀/mL) in live VHSV immersion vaccine-treated flounder challenged with VHSV at 10℃. This study demonstrated that flounder treated with the live VHSV immersion vaccine were resistant to VHSV infection, and the live vaccine was also safe for naïve fish even at a water temperature known to be VHS infectious.

• Journal of fish pathology
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• v.22 no.1
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• pp.35-44
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• 2009

The potential pathogenicity of Vibrio splendidus biovar II, which was isolated from triploid larvae of pacific oyster with bacillary necrosis and fish pathogenic V. anguillarum were investigated. The 5-day-old larvae infected with V. splendidus biovar II at the dose of $1.81{\times}10^{4}$ CFU/$m\ell$ started to die within 8 hours after exposure and the mortality were reached to 100% in 16 hours. However, $1.13{\times}10^{4-5}$ CFU/$m\ell$ of V. anguillarum caused 5.5-20% mortality of the larvae after 24 hours. The 10-day-old larvae infected with V. splendidus biovar II at the dose of $5.0{\times}10^{5}$ CFU/$m\ell$ showed mortality from 8 hours after challenge and led to a marked mortality of 90.47% after 24 hours. But V. anguillarum at doses of $5.08{\times}10^{3-6}$ CFU/$m\ell$ did not show mortality in the 10-day-old larvae. Therefore V. splendidus biovar II exhibited stronger virulence in 5-day-old larvae than 10-day-old and young oyster. Changes in the concentration of Vibrio in sea water showed that V. anguillarum decreased from $1.13{\times}10^{5}$ CFU/$m\ell$ to 1.7${\times}$105 CFU/$m\ell$ and V. splendidus biovar II increased from $1.81{\times}10^{4}$ CFU/$m\ell$ to $1.7{\times}10^{7}$ CFU/$m\ell$. This strong survival ability of V. splendidus biovar II in seawater was thought as one of the virulence factors against oyster larvae. The mortalities of 5-day-old and 10-day-old oyster larvae were decreased by addition of 30 $\mu{g}/m\ell$ of antibacterial agent(oxytetracycline or streptomycin). These results suggest that bacillary necrosis by V. splendidus biovar II can be occurred in oyster larvae in Korea. And virulence of V. splendidus biovar II is stronger than that of V. anguillarum in oyster larvae causing significant mortality at the density of $10^{4}$ CFU/$m\ell$.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.670-676
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• 2017

Recently, mass mortality of the young abalone Haliotis discus hannai has occurred in commercial seed production farms in Korea. The mortality rate was above 50% of the total cultured organisms in the farm, and the shell length of the moribund organisms was about 3cm. The mortal phenomenon was that the young abalones were weakly scattered on the bottom of the pond from the attachment matrix, or that they could not be moved back to their normal positions. The diseased farmed Pacific abalone had abdominal edema. From the edema in the moribund individuals, three bacterial strains were isolated and all the strains were identified as Vibrio harveyi. These strains were compared with thirty six strains isolated from the fish. The results was that the Vibrio harveyi from the fish were sorted into genogroup A or B; however, the three strains of the diseased farmed Pacific abalone were sorted into genogroup A and the new genogroup C. The identical mortality and pathological symptoms of the naturally infected organisms were reproduced by artificial infection with WA AG-1 and WA CS-5 strains. The $LD_{50}$ of WA AG-1 and WA CS-5 were each $1.0{\times}10^3cfu\;animal^{-1}$ and $1.7{\times}10^4cfu\;animal^{-1}$.

• Journal of fish pathology
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• v.22 no.1
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• pp.67-73
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• 2009

It was examined whether the common belief that "cultured puffer fishes do not contain tetrodotoxin (TTX)", the major lethal substance that accidently causes death in consumers of those fishes, is true in river puffer fish Takifugu obscurus. In mouse bioassay, lethal levels of toxins were detected in the ranks: gonad>liver>intestine>muscle>skin in wild puffer fish. In contrast, no mortality occurred in the mouse bioassay on cultured fish. However, there were sleepiness, sluggish behavior, and hind limb paralysis with the tissue extracts of cultured fish suggesting the presence of TTX or other similarly acting toxins. An attempt to confirm the presence of TTX in cultured fish with high performance liquid chromatography (HPLC) was not very successful. The results suggest possible existence of TTX toxins or similarly acting toxins.

• Journal of fish pathology
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• v.11 no.1
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• pp.61-67
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• 1998

For rapid detection of iridovirus infection, a PCR-based diagnostic method was developed. The genomic DNA from mortality-associated iridovirus was cloned into pUC19 vector. The nucleotide sequences of these clones were compared with sequences of other genes from EMBL/GenBank databank. Based on the nucleotide sequences, PCR primers were prepared and used for PCR. The DNA amplification did not occur from the normal fish cells. In contrast, DNA was amplified from the iridovirus-infected fish cells and purified iridovirus. These results suggest that mortality-associated iridovirus can be detected from virus-infected cells within short time and this PCR-based diagnostic system provides a simple and accurate method for detecting the presence of iridovirus infection.