• Journal of fish pathology
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• v.28 no.3
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• pp.171-174
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• 2015

Previously, we had reported that some Miamiensis avidus, a major pathogen of scuticociliatosis in cultured olive flounder, strongly agglutinated by flounder immune sera could escape from the agglutinated mass within a few hours. In the present study, we observed that M. avidus not only escaped from the agglutinated mass but also conducted division(s) before shedding its old covering. Furthermore, ciliates that survived the antibody-dependent complement killing (ADCK) assay were not killed even when re-exposed to a freshly prepared ADCK assay. This result suggests that the liberated ciliates from the ADCK assay might change not only their i-antigen types but also the epitopes of major surface antigens, which debilitate antibody-mediated complement killing ability.

• 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.

• Journal of fish pathology
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• v.20 no.1
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• pp.49-60
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• 2007

Non-hemolytic Streptococcus parauberis isolated from diseased olive flounder, Paralichthys olivaceus in the South coast of Korea were identified by physiological, biochemical and genetic analysis in order to define the different characteristics geographically. First, twelve strains of S. parauberis were isolated from catalase-negative gram-positive cocci by multiplex PCR assay. Phenotypic identifications were performed with commercially available kit (API 20 Strep and API ZYM system). Analysis of API profiles of the isolates showed that strains were identified as either of Lactococcus lactis, S. constellatus or S. uberis. Moreover, S. parauberis isolated from olive flounder differed from that of turbot (X89967) to the test of not Voges-Proskauer, arginine, hippurate, alkiline phosphatase and pyrroidonyl arylamidase but β-glucuronidase. All S. parauberis isolates were sensitive to florfenicol, ampicillin, ofloxacin and vancomycin but were resistant to oxolinic acid, flumequine, nalidixic acid and sulfisoxazol. However, the 16S rDNA sequences of the isolates showed 99% similarity to S. parauberis KCTC 3651 (AY584477) and a great homogenecity among the flounder isolates.

• Journal of Aquaculture
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• v.20 no.2
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• pp.106-113
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• 2007

Biological characteristics of Philasteridies dicentrarchi (Ciliophora:Scuticociliate) isolated from the cultured olive flounder Paralichthys olivaceus was determined out by culture, growth conditions, and in vitro relief effect of chemical compounds. The scuticociliate has an active propagation ability by utilizing organic matters obtained from cell strain, bacteria, assorted feed, brain tissue and rotifer tissue. The ciliate achieved population growth activity under the conditions of $5{\sim}45\;ppt$ in salinity and pH 6-9. The ciliate had survived and propagated under the water temperature ranging $10{\sim}30^{\circ}C$, but active growth was observed in the temperature ranges of $10{\sim}25^{\circ}C$. Therapeutic trials were performed with formalin and hydrogen peroxide. The extermination time of the parasites with formalin was in 30 minutes both at 300 and 400 ppm, 60 minutes at 200 ppm, 90 minutes at 100 ppm, and 120 minutes at 50 ppm, respectively. In hydrogen peroxide treatments extermination time was 60 minutes in 300 ppm, 90 minutes in 200 ppm, and 150 minutes at 150 ppm and 100 ppm concentrations.

• Journal of fish pathology
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• v.26 no.3
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• pp.149-161
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• 2013

Viral haemorrhagic septicaemia virus (VHSV), the causative agent of viral haemorrhagic septicaemia (VHS), is an epidemic virus of cultured olive flounder Paralichthys olivaceus in Korea. In the present study, the entire glycoprotein (G) gene including several hypervariable regions from 36 isolates of diverse geographic and host origin and 8 Korean VHSV isolates from cultured olive flounder were analyzed. Phylogenetic analysis indicated that most of Asian VHSV belong to the genotype IVa group, suggesting that they originated from a common ancestral virus. Comparative sequence analysis of the complete G protein from Korean VHSV isolates revealed 3 Korean strain-specific nucleotide residues (nucleotide number of G-region: A755, T834 and T1221). These results suggest that Korean VHSV originated from a common ancestor, but these regional specific nucleotide sequences suggest that genetic differences of VHSV are more related to geographic areas than to host fish species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.539-546
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• 2019

The major cultured marine fishes in sea off the coast Gyeongsangnam-do Province, South Korea, were assessed and included 9.3% rockfish Sebastes schlegelii, 7.8% red seabream Pagrus major, and 2.1% rock bream Oplegnathus fasciatus. The number of insurance payments related to disease mortality in cultured fish in 2017 was fourfold that in 2016. Economic loss in aquaculture due to disease in cultured fish is high and represents an important inhibitory factor affecting marine fishery productivity. In 2018, diseases led to severe production losses in several aquaculture species: 40.0% in rockfish, 11.4% in olive flounder Paralichthys olivaceus, 10.0% in filefish Thamnaconus modestus, and 9.3% in red seabream. Fish-parasitic pathogens such as Microcotyle sebastis, Alella spp., and Dactylogyrus spp. enter mainly via the gills and skin surface. Among bacterial pathogens, Vibrio species were most common, with Vibrio harveyi being the dominant species causing infections in these fishes. The bacterium Lactococcus garvieae is thought to exhibit host specificity in fish. The fish species in the present study exhibited a higher tendency for infection by heterologous pathogens than by a single pathogen; therefore, it is necessary to devise new strategies for treating diseases in cultured fish.

• Journal of Aquaculture
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• v.11 no.3
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• pp.285-294
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• 1998

When Cochlodinium polykrikoides came into the culture tanks through influent cultivated water during the red tides, hundred thousands of commercial flounders were concomitantly killed and many culturists suffered from a great deal of financial loss in the east coast of Korea. It is charactrized by high sinking rate after sunset and the formatino of clump which results in oxygen deficiency by its respiration at tank bottom under condition. We investigated the efficacy of hydrogen peroxide and chlorine dioxide, known to form radicals, for extermination of red tide organism C. polykrikoides. When C. polykrikoides seawater with a density of 6,000 cells/$m\ell$ was treated with 14, 28 and $42mg/\ell$ of hydrogen peroxide, its survival rate was markedly decreased to 9.8, 0.8 and 0.3% respectively immediately after 6 hours of treatments whereas when it was treated with 1.5, 2.1 and $3.0mg/\ell$ chlorine dioxide, its survival rate showed 87.7, 81.3 and 80.1 and 80.1% respectively at the same treatment time. Hydrogen peroxide was the effective agent since it has scarcely injured the cultured olive flounder when exposed to the tested concentration range of $14~28mg/\ell$ with the extermination of almost3 C. polykrikoides during the experimental period of 5 days and has shown the oxygen increase of approximately $1.23mg/\ell$ 2 hours immediately after the flounder by C. polykrikoides in the land-based culture tank is assumed to be not by the toxicity of itself but by oxygen dificiency from the rapid respiration of dinoflagellate clump sunken to the tank bottom.

• Journal of Aquaculture
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• v.15 no.4
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• pp.267-273
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• 2002

Effect of heated water from a power plant in summer on hematological characteristics of flounder (Paralichthys olivaceus) were investigated. Hematocrit level fluctuated between 15.7 and 16.3% in control farm, but it significantly increased to 17.7% in the high-WT farm. The corresponding values for hemoglobin concentration were 9.9~18.0 $g/㎗$ for the control farm and 6.2~19.4 $g/㎗$ for the exposed farm. The plasma cortisol remained between 0.6 and 2.8 ng/$ml$ in the former but significantly decreased 317.1 to 3.3 ng/$ml$ in the later. The plasma glucose also decreased from 36.5~46.0 to 23.5~36.5 mg/$dl$. Plasma osmolality decreased from 551.5~597.0 to 391.0~466.5 mOsm/kg.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.4
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• pp.234-242
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• 2007

We examined the cause of albinism in a hatchery population of flounder in terms of environmental and nutritional factors, including the effects of light intensity (130-12,300 lux), photoperiod (12L/12D or 24L/0D), tank substrate (concrete or fiber-reinforced polymer), tank color (white or dark green) and supplement with enriched live food, and also compared the growth of normal and albino fry under both 12L/12D and 24L/0D. Further to, normalization of the skin pigmentation pattern on the ocular side has been juvestigated after rearing the albino fry for 2 years after their identification and classification and found that, light intensity did not play a critical role in the development of normal pigmentation or albinism in the flounder. By contrast, the photoperiod was a weak inducer of albinism in the flounder. Tank substrate and color also affected the hypomelanosis on the ocular side of the flounder fry. The choice and supplementation of enriched live foods could drastically reduce the incidence of albinos in hatcheries. On comparing the growth of normal and albino fry, while there was no difference between the groups under 24L/0D, the growth of the albino flounder was slower under 12L/12D. Although coloration resulting from xanthophore and melanophore, but not iridophores, occurred on the ocular side, evidence of albinism remained on the ocular side of flounders.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.2
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• pp.123-130
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• 1995

This study was performed to obtain the basic data on the serum components of several marine fish species commonly cultured in Korea. Blood samples taken from five species of fish were analyzed for various components of serum, total protein (TP), albumin (ALB), triglyceride (TG), cholesterol (CHOL), glucose (GLC), sodium (Na). Potassium (K), chloride (Cl), Phosphorus (P), lipase (LIPA), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The fish used were coho salmon(Oncorhynchus kisutch), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder ( Paralichthys olivaceus) and parrot fish (Oplegnathus fasciatuss) reared at the Chungmu Experimental Fish Culture Satation of KORDI. TP concentration of warm-water species (2.9-5.1 g/dl) was higher than that of cold-water species, and ALB concentration was ranged at the level of 1.2-1.9 g/dl. Coho salmon showed the highest ration of A/G(1.1), and the other species were about 0.5-0.6. The concentrations of TG and CHOL, components of lipids, varied with the different species. The concentration of TG was high, but CHOL concentration was low in olive flounder, while the reversed results were shown by sea bass. The sum of these two components was the highest with 600mg/d1 in olive flounder, and about 400mg/d1 for sea bass and rock fish, and 300mg/d1 for parrot lish and coho salmon. Concentration ot GLC in coho salmon and rock fish ranged from 61 to 76mg/d1 which were about lour times higher than that of flounder. The highest lipase activity was observed in coho salmon, while it was nearly nil in flounder. The reversed tendency was found for TG concentration. Mineral concentrations of Na, Cl and K were 160-204 mmol/l, 137-183mmo1/1 and 0.5-3.1 mmol/l, respectively, but no significant difference between the species was observed. However, the concentrations of P were high in relatively active species such as coho salmon and rockfish. AST activity in all species examined was higher than that of ALT with being highest in coho salmon. The highest ALT activity was found in olive flounder.