• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1157-1170
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• 2023

Ascites is a condition in which body fluids are abnormally accumulated in the fish's abdominal cavity, and is an important indicator of the health of flounder. Ascites can occur in the process of infection with bacteria, viruses, parasites, etc., which causes abdominal distension, sluggish growth, and weight loss. In this paper, we tried to find the correlation with other symptoms or diseases that affect ascites symptoms in flounder. As experimental data, ascites symptoms were divided into three states: no ascites, ascites transparent, and ascites opaque, and disease diagnosis data of cultured flounder collected for 7 years were used. After performing an appropriate preprocessing process for the random forest machine learning method, other symptoms and disease factors related to ascites were extracted, and it was confirmed that the proposed model could present the main factors related to ascites.

• Fisheries and Aquatic Sciences
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• v.23 no.8
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• pp.20.1-20.18
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• 2020

Background: Olive flounder, Paralichthys olivaceus, is an economically important aquaculture species in Korea. Olive flounders have been heavily damaged by streptococcal infections every year and are treated with antibiotics. However, antibiotic abuse is causing the emergence of resistant strains, and to overcome this, research has shown that new antibiotics must be applied. Tylosin is a relatively safe antibiotic and has good activity against Gram-positive bacteria and mycoplasma. We studied the therapeutic effects and side effects of tylosin on Streptococcus parauberis-infected olive flounder. Methods: After artificial infection of olive flounder with S. parauberis SPOF18J3, an appropriate dose of tylosin was confirmed by intramuscular injection (I.M.) at 2.5, 5, 10, and 15 mg/kg, and oral administration at 10 and 20 mg/kg. After I.M. and oral administration dosing of tylosin, side effects were confirmed by serological analysis, histopathological analysis, and median lethal dose (LD₅₀) analysis at both an appropriate concentration and a high concentration. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey's test (p < 0.05). Results: The appropriate I.M. and oral administration concentration of tylosin administered to olive flounder infected with S. parauberis SPOF18J3 was found to be 10 mg/kg. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were showed not significantly different between the control group and the experimental groups. The histopathologic results showed mild inflammatory responses in muscle and tubular vacuolization and tubular atrophy appeared, but there were no significant differences between the groups. The LD₅₀ was confirmed to be 461 mg/kg. Conclusion: In this study, an effective treatment method was provided by verifying the treatment effects and side effects of tylosin in olive flounder infected with S. parauberis, which can be applied directly to aquaculture sites. In addition, these results may be used as a reference for evaluation required upon request to obtain approval for tylosin antibiotics as fishery antibiotics in Korea. After approval, it is possible that a fishery disease manager will be able to prescribe and sell the antibiotic tylosin.

• 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.

• Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.234-240
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• 2023

Enteromyxum leei has been identified as the causative agent of emaciation disease in a wide range of marine fish hosts. In this study, we aimed to determine the effect of the parasitic infection of Enteromyxum species on starry flounder that were cultured in aquaculture farms of Jeju island in Korea. As the mortality of cultured olive flounder Paralichthys olivaceus because of E. leei infection increased, some fish farms on Jeju island attempted to culture the starry flounder Platichthys stellatus, as an alternative. Myxosporeans with a developmental stage similar to E. leei were found in the intestines of cultured starry flounders. The partial 18S rDNA of myxosporeans showed 100% similarity with E. leei. To reveal the effect of E. leei infection on starry flounder, the intensity of E. leei infection measured using quantitative polymerase chain reaction, and the condition factor (CF) of fish were measured and analyzed statistically. The results showed that high-intensity E. leei infection significantly decreased the CF of the starry flounder. However, the pathogenicity of E. leei to starry flounder is low, considering its mortality and clinical signs.

• Journal of fish pathology
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• v.17 no.3
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• pp.159-169
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• 2004

Bacterial wihte enteritis ocurred by infection of V. ichthyoenteri is a devastating disease in olive flounder (Paralichthys olivaceus) hatcheries in Korea. Since white enteritis has been a problem in aquqtic industries, necessity of a rapid detection method is increased. In an attempt to develop rapid PCR method the detection of V. ichthyoenteri, we examined the 16S-23S rRNA intergenic spacer region(ISR) of V. ichthyoenteri and developed species-specific primer for V. ichthyoenteri. The intergenic spacers were amplified by primers complementary to conserved region of 16S and 23S rRNA genes. The intergenic spacer region between the 16S and 23S rRNA genes of V. ichthoenteri were investigated by PCR fragment length typing and DNA sequencing. Analysis of the ISR sequences showed that V. ichthyoenteri contains one types of polymorphic ISRs. The size of ISRs ranged 348bp length and not contains tRNA genes. Mutiple alignment of representative sequences from different Vibrio species revealed several domains of high sequence variability, and allowed to design species-specific primer for detection of Vibrio ichthyoenteri. PCR. The specific of the primer was examined using genomic DNA prepared from 19 different Vibrio species, isolated 18group Vibrio species. The results showed that the PCR reaction using species-specific primer designed in this study can be used to detect V. ichthyoenteri.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.460-465
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• 2006

An 8-week feeding trial was conducted to investigate the effects of dietary supplementation with probiotics as a feed additive for Juvenile olive flounder (Paralichthys olivaceus). Three experimental diets supplemented with Bacillus polyfermenticus (BP), Bacillus licheniformis (BL), or Bacillus polyfermenticus plus Saccharomyces cerevisiae, (BP+SC) at $1.0{\times}10^7CFU/kg$ diet on a dry-matter basis were prepared. The basal diet was used as a control. After the 8-week feeding trial, the respiratory burst activity (NBT assay) of fish fed the BP + SC diet was significantly higher than that of fish fed the control diet. Fish fed the BP, BL and BP + SC diets had significantly lower cumulative mortality than did fish fed the control diet after the third day of the challenge test (P<0.05). However, there were no significant differences among fish fed the experimental diets in weight gain, feed efficiency, protein efficiency ratio, hematosomatic index, condition factor, survival rate, or Iysozyme activity. Results could suggest that dietary B. polyfermenticus, B. licheniformis, and B. polyfermenticus +S. cerevisiae enhance nonspecific immunity and disease resistance in juvenile olive flounder.

• Journal of fish pathology
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• v.27 no.1
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• pp.35-45
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• 2014

In this study, we investigated the effects of dietary 1% garlic extract on nonspecific immune responses and fish diseases (Viral Hemorrhagic Septicemia Virus, Vibrio anguillarum, Streptococcus iniae and Edwardsiella tarda) resistance in olive flounder Paralichthys olivaceus. Fish were fed a commercial diets supplemented with 1% garlic extract for 4 weeks. After the 4 weeks feeding experiment, the artificial infection was made by V. anguillarum, S. iniae, E. tarda and VHSV. And the cumulative mortality was monitored for 2 weeks after artificial infection. The cumulative mortalities decreased in all experiments except for group of E. tarda compared to control group. We observed significantly higher levels of the hematocrit, glucose, total protein, lysozyme activity and the macrophage activity in the experimental group compared to the control group. In the experiments of drug sensitivity and MIC using the three bacteria (V. anguillarum, S. iniae and E. tarda), 1% garlic extract was more effective than the previously reported fermented garlic powder. These results suggested that garlic extract can increase the disease resistance of olive flounder against V. anguillarum, S. iniae and VHSV and the ability of nonspecific immune responses.

• Journal of Life Science
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• v.17 no.10
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• pp.1434-1440
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• 2007

We have investigated the effects of mushroom mycelium (Phellinus linteus, Coriolus versicolor) mixed cultural extract on the immune responses of olive flounder, Paralichthys olivaceus. The mixed culture extracts were evaluated for the growth, hematology, lysozyme activity, leukocyte phagocytic activity, and disease resistance against Vibrio anguillarum. In the effect of the growth, the body weight and length gain in the group, which fed with mushroom mycelium mixed cultural extract, were 52 g and 3.4 cm higher than that in the control, respectively. For the hematology, the administration of mushroom mycelium mixed cultural extract resulted in increase of glucose. However, there was no distinct differences in GOT (glutamic oxaloacetic transaminase), GPT (glutamlc pyruvic transamlnase), TG, TP, and LDH (lactate dehydronase) among each group. The activities of lysozyme were 80% higher in the experimental groups than in the control. The activities of leucocyte were 66% higher in the experimental groups than in the control. Although lysozyme activity and leucocyte activity showed somewhat decrease after 12 weeks, these activities were still higher than in the control. The cumulative mortality (%) after an artificial challenge with $7{\times}10^8\;CFU$ of Vibrio anguillarum per fish was 25% higher in the experimental groups than the control.

• Journal of fish pathology
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• v.26 no.2
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• pp.59-64
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• 2013

This study aimed to develop an algorithm to determine the optimal injection position in olive flounder, Paralichthys olivaceus when a vaccine is injected into the fish by using a vision-based automatic equipment measruing the total length (TL), width and weight of the fish. Over a 5-month period, 500 olive flounders were examined to analyze the relation of the fish size and to the shape and location of its abdomen, using radiography, a ruler plate and scale. There were significant correlations between the TL and the shape and location of the abdomen. The abdomen was located 0.232TL - 2.7221 mm ($R^2$=0.8787) from the end of the mouth of the fish. The height and width of the abdomen in the fish were 0.1292TL + 1.8768 mm ($R^2$=0.7935) and 0.183TL-5.9791 mm ($R^2$=0.8641), respectively. The injection point in the abdominal region avoiding organs was determined by calculating the center of gravity of the abdomen volume. This can be expressed as g (0.2759TL - 2.0965, 0.1295TL - 4.2325) on the basis of TL line coordinates. The injection point by the expressed coordinates had errors for the x and y axes as 12.15 mm and 8.28 mm, respectively. These were enough to use the algorithm to injection for the equipment. This automated method to determine the position of any part in the fish can also be used for other purposes, for example, intramuscular injection or auto-tagging of fish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.440-445
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• 2008

Ciprofloxacin is the most commonly used fluoroquinolones for treating bacterial disease in olive flounder (Paralichthys olivaceus) farming, but its withdrawal time for industrial-scale farming has not been established. The depletion of ciprofloxacin was investigated in the olive flounder under field conditions. Fish were kept in an inland fish farm and fed a commercial diet containing 5 mg/kg of ciprofloxacin for 13 days. Seven fishes per sampling time were examined during and after the treatment. Ciprofloxacin and its major metabolite, enrofloxacin, were analyzed using HPLC with a fluorescence detector. The concentrations of ciprofloxacin and enrofloxacin in muscle increased during the medication period, and then decreased rapidly. The ciprofloxacin and enrofloxacin concentration in the olive flounder peaked on days 11 and 13, respectively, with maximum concentrations in muscle of 0.58 and 0.73 mg/kg. Residual ciprofloxacin and enrofloxacin were eliminated rapidly; 6 days after treatment, the respective levels in muscle were 0.04 and 0.10 mg/kg and neither was detected 15 days post treatment. The level of ciprofloxacin accumulation at the beginning of oral administration was variable according to the farming conditions, but the overall exhaustion time was similar. In conclusion, an adequate withdrawal period for enrofloxacin is 15 days in the case of oral ciprofloxacin administration.