• Food Science and Biotechnology
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• v.18 no.2
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• pp.533-536
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• 2009

Withdrawal time of erythromycin in the cultured black rockfish (Sebastes schlegeli) was investigated to provide regulatory authority and fishery industry with full information needed to secure food safety of the fish treated with erythromycin. Medication was carried out using the experimental diet containing erythromycin of which concentration was 200 mg/kg diet and its daily dose was about 40 mg/kg body weight. The withdrawal time needed to reduce antibiotic contents around 10.0 mg/kg accumulated during 9 days medication below 0.2 mg/kg was identified about 10 days. The antibiotic with 13.7 mg/kg of fish on the $9^{th}$ days of medication was completely depleted after 30 days from stop of medication.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.79-83
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• 2010

Since 1998, a new viral disease with high mortality has been consistently recorded in Korea in cultured carp, Cyprinus carpio. In this study, we investigated an epizootic of the disease that caused high mortality rates in carp obtained from 11 farms in Korea between 1999 and 2007. Assessment of koi herpesvirus (KHV) levels in diseased carp was carried out to determine if this virus was the etiologic agent of disease in this instance. High mortality rates in carp were recorded mainly in the spring and autumn at water temperatures between $19^{\circ}C$ and $24^{\circ}C$. Diseased fish typically showed surface discoloration, with a thick opaque mucus covering the body and gills. Protozoan parasites and bacteria were recovered from 7/29 (24%) and 2/26 (8%) of fish, respectively. Evidence of viral infection was marked; cytopathic effects (CPEs), characterized by cell rounding and an extended cytoplasm in fathead minnow (FHM) cells, were detected in 40/41 fish (98%). A high mortality rate (80%) resulted when supernatants of cell cultures showing CPEs were applied to previously healthy fish. KHV was detected by polymerase chain reaction in 6/41 fish (15%), but was not detected in supernatants obtained from cell cultures showing CPEs. These results suggest that KHV may not be the etiologic agent of the high mortality occurring among cultured carp in Korea; therefore, some other-as yet unidentified-infective agent must be responsible.

• Journal of fish pathology
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• v.35 no.1
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• pp.47-56
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• 2022

Lincomycin as one of the lincosamides antibiotics have been mainly used in human and livestock fields, but have not been used in aquaculture. In this study, the distribution of minimum inhibitory concentration (MIC) values against lincomycin and the detection of the macrolide-lincosamide-streptogramin (MLS) resistance gene were confirmed in bacterial pathogens isolated from cultured olive flounder (Paralichthys olivaceus). Of the 107 strains isolated from Jeju, 36 strains of Gram-positive bacteria and 71 strains of Gram-negative bacteria were identified. Most of Streptococcus spp. was found to have a MIC value of less than or equal to 0.5 ㎍/mL, and Edwardsiella piscicida was found to have a MIC value higher than 1,024 ㎍/mL. V. harveyi and V. alginolyticus mostly showed MIC values of 256 ㎍/mL, but V. scophthalmi displayed values of 8~64 ㎍/mL. In the detection of MLS resistance gene, erm(B) was detected in 9 strains of Streptococcus spp., and erm(A) was confirmed in one strain.

• Journal of fish pathology
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• v.6 no.2
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• pp.205-218
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• 1993

On the development of hirame(Paratichtys olivaceus) culture, outbreak of scuticociliata infection was reported to cause severe damage in Japan. To establish effective measures for isolation and cultivation of this ciliate, we tried to culture this pathogenic ciliate using medium for bacteria and fish cell lines in vitro. Scuticociliata from the brain tissues of infected fish was aseptically inoculated to CHSE-214 cells cultured in MEM-10 without antibiotic. Scuticociliata grew well and the number of ciliate reached $10^6\;cells/ml$ at temperatures of $15^{\circ}C$ to $20^{\circ}C$ for 10d. The number of ciliate cultured in the cell lines is 10 times higher than the numbers cultured in the liquid medium alone. This ciliata could be cloned by dilution method. Scuticociliata isolated could grow well on 42 different cell lines that were established from marine fish, warm freshwater fish, and salmonids. This ciliate could be preserved in liquid nitrogen for more than 6 months. Subsequently, we observed the optimal temperature and salinity for growth, and tested the sensitivities of this organism to formaldehyde, flagyl(Metronidazole), Ekuteshin(Combination compound of sulfamonometoxin and ormethoprim), and ozonixation. Optimal temperature for growth was $25^{\circ}C$ and salinity was 1.0 to 1.5%. Washed scuticociliata was killed by formaldehyde at the concentration of 50ppm for 10min, but was not completely killed even at a high concentration of 400ppm for 20min in MEM-5. Flagyl and Ekuteshin can inhibit the growth of scuticociliata at the concentration of 1,000 and $100{\mu}g/ml$ in MEM-10, respectively. More than 99% of this scuticociliata could be killed by ozonization at a dose equivalent to $1.0mg/\ell$ oxidant for 30sec in sea water. Isolated scuticociliata showed the pathogenicity to the cultured hirame by artificial infection(I. P. injection, $10^5\;cells$/fish). The number of scuticociliata in the water could be counted by most probable number(MPN) method using tissue culture, and the minimum detectable number was $1.8\;cells/\ell$. The number in the reservoir tank for water supply to the culture tank was 110 cells/l. After cleaning by elimination of the sediments from of the reservoir tank and disinfected with formaldehyde, number of scuticociliata decreased and was counted less than $1.8\;cells/\ell$ and infection rate of cultured hirame was decreased.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.5
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• pp.609-615
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• 2012

A histo-pathogical examination was carried out to evaluate the effect of commercial extruded pellet (EP) and a raw fish moist pellet (MP) diet on the health of juvenile rockfish cultured in marine net-cage for 7 months. Fish were distributed randomly to each net cage as a group of 76,000 fish (initial mean body weight 5.9 g). After 2 months, the hypertrophy or swelling of liver parenchymal cells was identified in most individuals and lasted until 7 months. Livers in EP fed group frequently showed hypertrophic parenchyma and fatty change with occasional atrophic cells. However, after 4 months, lymphocytic infiltration in splenic parenchyma was seen in a number of individuals. In addition, the gastric glandular epithelium was atrophied and in the lumen of renal tubules protozoan parasites were frequently identified but there was no correlation with the type of feed. Moreover, juvenile rockfish on EP diet showed gross and microscopic hypertrophy of the liver which would be due to oversupply of feed. Severe hepatic cellular hypertrophy or swelling could lead to the damage of microcirculation. Especially fatty change and atrophic change of liver could be the result from the damage, which could be responsible for immunological problem. Lymphocytic infiltration of spleen on the MP diet suggests that juvenile rockfish could be frequently exposed to infectious antigens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.689-692
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• 1999

Proximate compositions of muscles and eggs between wild sweet smelt which were caught in Seomjin river and Miryang river, and cultured sweet smelt which were purchased from certain cultured farms in Hadong and Miryang, were compared. Proximate compositions of wild sweet smelt muscles were $76.7\~77.5\%$ for moisture, $18.4\~19.9\%$ for protein, $2.41\~3.47\%$ for lipid, and $1.04\~1.33\%$ for ash content and there were almost no differences between the fishes from Seomjin and Miryang river. Protein and ash content in the cultured fish muscles were similar to those of the wild fish muscles, while the former contained much more lipid and carbohydrate, and less moisture than the latter, especially lipid content differed greatly according to their cultured farms. This might be the result of their different diet compositions. Lipid, protein and carbohydrate content in eggs of the wild and cultured fishes were much higher than those in their muscles. There was a negative correlation between moisture and lipid content in all samples; y= -0.2715x+24.903 (r= -0.7253, p<0.001).

• Journal of Aquaculture
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• v.11 no.4
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• pp.547-556
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• 1998

This study was performed to obtain the basic data on the serum constituents of several marine fish spesies commonly cultured in Korea. Blood samples taken from six species of fish were analyzed for various components of serum, total protein (TP), albumin (ALB), triglyceride (TRIG), cholesterol (CHOL), glucose (GLC), lipase (LIPA), amylase (AMYL), aspartate transaminoferase (AST), sodium (Na), potassium (K), chloride (CI) and phosphorus (PHOS). The fish used were coho salmon (Oncorhynchus kisutch), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder (Paralichthys olivaceus), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder (Paralichthys olivaceus), parrot fish (Oplegnathus fasciatus) and jack mackerel (Trachurus jaonicus) reared at the Chungmu Experimental Fish Culture Station of KORDI when the water tempetature was ca. 16.5$^{\circ}C$. There were significant differences in TRIG, CHOL, LIPA and AMYZ among the species analyzed. TRIG concentratin were ranged 178~180mg/dl in jack mackeerel and rock fish, 126~159 mg/dl in olive flounder and sea bass, and 102~114 mg/dl in coho salmon and parrot fish, respectively. Jack mackerel showed the highest levels in CHOL (255mg/dl) and GLC(138mg/dl) among species. LIPA levels were recorded 256 U/dl in coho salmon, 41~42 U/dl in parrot fish and rock fisk, and 5~11 U/dl jack mackerel and sea bass, respectively. AMYL activity of coho salmon was measured as 2, 665 U/dl, and that of jack mackerel was 1,210 U/dl while sea bass showed 60 U/dl and parrot fish, olive flounder and rock fish had at most 5 U/dl. On the other hand, there was no significant difference in the concentration of Na and CI. Na and K were proved that they were negatively correlated in all the species. Generally, among blood components, PHOS and CHOL levels were different depending on environmental temperature of each fish species, especially in olive flounder. Rock fish and parrot fish showed high blood concentration of those components during low temperature period while olive flounder and jack mackerel reached high level during their optimal environmental temperature period. The electrolyte concentration and LIPA activity were high during low water temperature period, in general, but TP and ALB concentrations were high during optimal temperature period. The concentrations of TRIG, CHOL and GLC, those which were used as energy sourses, were different among species by season.

• Fisheries and Aquatic Sciences
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• v.9 no.3
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• pp.123-128
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• 2006

An epizootic causing mortality among cultured marine finfishes occurred in 1999 in the province of Kyoungsang, Korea. The disease was characterized by the presence of enterocele, abdominal swelling, and gastroenteritis. The causative bacteria were isolated from olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), turbot (Scophthalmus maximus) and the rearing water. These bacteria showed swarming activity on agar plates and yellowish or greenish colonies on thiosulfate-citrate-bile salts-sucrose (TCBS) agar plates, but no luminescence. The pathogen was identified as Vibrio harveyi based on morphological and biochemical characteristics and the sequence of l6S rDNA. The lethal doses (LD$_{50}$) of olive flounder and black rockfish were estimated to be $1.24\times10^6-1.36\times10^8$ and $3.24\times10^5-5.8\times10^7$ CFU/fish respectively following intraperitoneal injection.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.171-179
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• 2001

The effect of $\alpha-Tocopherol\;(\alpha-Toc)$ level in diet on the biochemical property of sweet smelt, Plecoglossus altivelis, was investigated. The cultured sweet smelt fish were fed two different diets for 8 weeks; a control diet was added $0.01\%$ of $\alpha-Toc$ (CO group) and an experimental diet was added $1.00\%$ of $\alpha-Toc$ (HT group). Both diets were rich in docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), accounting for $12.3-13.2\%$ and $12.1-12.4\%$, respectively. Growth rate (GR) and feed efficiency (FE) were almost no difference between both groups, but female fish of both groups were superior to male fish in GR and FE. Lipid contents of muscle and ovary were high in CO group compared with HT group, but that of testis showed a similar level in both groups. The proportion of polyunsaturated fatty acids (PUFA) in muscle showed almost no difference in sex and between both groups. In testes, the proportion of PUFA was 1.35 times for HT group to 1.54 times for CO group as much as in ovaries, in which was high approximately 1.5 times compared with muscle. Thiobarbituric acid-reactive substances (TBARS) and hydroxyl (OH) radical levels of plasma were higher in CO group than HT group and superoxide dismutase activity was also slightly high in the former. The intensity of watermelon-like or cucumber -like aroma was related positively with TBARS and OH radical levels in plasma. The level of triglyceride (TG) and total cholesterol (CHOL) in plasma of CO group was higher than those of HT group. Survival rate was high in CO group with higher level of TG and CHOL in plasma.

• Journal of fish pathology
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• v.33 no.1
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• pp.91-95
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• 2020

Fish bacterial diseases have spread and caused serious problem for cultured marine fish in Korea. The important bacterial disease affecting mariculture such as olive flounder (Paralichthys olivaceus) are caused by Edwardsiella tarda, Vibrio scophthalmi and Streptococcus parauberis. For the bacterial disease protection in aquaculture industry, the water treatment is needed in aquaculture system. During the last decades atmospheric pressure non-thermal plasma in contact with liquids have received a lot of attention of environmental and medical application. In this study, we determined the disinfectant effect in seawater and three major fish bacterial disease pathogens by using low frequency plasma treatment. Three fish bacteria (E. tarda, V. schophthalmi, S. parauberis) were not detected within 16 min, 150 min and 270 min of 20 L, 500 L and 1 ton seawater post low frequency plasma treatment, respectively. Three major fish bacterial disease pathogens were not detected within 2 min after the low frequency plasma treatment, suggesting that the low frequency plasma possess disinfectant effectiveness.