• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.161-165
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• 2001

Artificial fertilization (dry method) of mature right-eye flounder, Limanda yokohamae (female : 25.1~30.4 cm in total length (TL), male : 24.5~28.5 cm in TL), obtained from the fish market in Dolsan-do, Yosu was performed in the Fisheries Exhibition. Hatched larvae and juveniles were reared to describe their morphological development. Newly hached larvae attained 3.13~3.42 mm in TL. Their eyes were yellowish brown and their mouth and anus were not yet opened. Three to six days after hatching the larvae attained 3.35~4.61 mm in TL. Their mouth and anus were open and the yolk sac was almost absorbed. Feeding activity increased as the mouth became larger. At 25 days, the larvae attained 5.47~5.91 mm in TL. The caudal notocord was flexed $45^{\circ}$ upward. At 35 days, the larvae attained 6.83~7.60 mm in TL. Rays of the dorsal and anal fins were formed, and the left eye was moved slightly to the right side of the head. At 55 days, the juveniles attained 9.38~11.73 mm in TL. The left eye was moved completely onto the right side. All of the fins had complete set of the fin rays, and the juveniles spent most of the time on the bottom resting on their blind side (D. 68~70 : A. 50~52 : P. 11: V. 6 : C. 18~19).

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.117-123
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• 2012

The starry flounder Platichthys stellatus, like all flatfish, exhibits conspicuous lateral asymmetry in numerous traits, most obvious of which is the migration of one eye to the other side of the head during metamorphosis. Additional changes related to eye migration include asymmetrical pigmentation, and a behavioral shift from larvae that exhibit upright, open-water swimming to juveniles and adults that lie on the ocean floor, eye side up. However, the morphology of these juveniles has been quite plastic in recent years, a phenomenon which is thought to be related to a diverse suite of semi-intensive and intensive larviculture methods. The cause of morphological abnormalities in the farmed flatfish is poorly understood. In the present study, we observe the features of morphological specificity and abnormality of immature fish (mean total length 23 cm) and survey the occurrence frequency of the specificity and abnormality of juvenile (mean total length 6.70 cm) in artificial culture facility. We find 2 types of abnormality (e.g., albino in ocular side and hypermelanosis in blind side) and 1 type of specificity (e.g., lateral polymorphism). These considerably differ from normal individuals (has sinistral eye and pigmented on only one side) by several characteristics (dextral eye, ocular side albinism, blind side hypermelanosis). The incidences of albinism, hypermelanosis, and body reversal are $10.1{\pm}2.56%$, $91.7{\pm}1.7%$, and $13.1{\pm}1.1%$, respectively. These suggest that these morphometric and morphological differences occur more in artificial environment during and just after metamorphosis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.861-869
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• 2023

This study aimed to evaluate the effectivity of full-fat black soldier fly Hermetia illucens (BSF) and defatted mealworm Tenebrio molitor (MW) larvae meal as a fish meal (FM) substitute in a low-fish meal (LFM) diet for juvenile olive flounder Paralichthys olivaceus. The LFM diet comprising 45% FM with tankage meal, poultry byproduct meal, soy protein concentrate and wheat gluten was the control diet. Three experimental diets were 10% FM in Con with BSF, MW and a mixture of both at the same ratio (designated as B10, M10 and B5M5, respectively). Four hundred and forty-fourth juvenile P. olivaceus (34.3±0.1 g) were randomly distributed into 12 tanks (425 L) in three replicate groups per treatment and fed the experimental diets for 15 weeks. At the end of the feeding trial, growth performance, survival, biological indices (condition factor, viscerosomatic index, hepatosomatic index), non-specific immune responses (lysozyme, myeloperoxidase) and intestinal histology (villi length and goblet cells) were not significantly affected by treatments. Feed utilization was significantly decreased in M10 compared to the control group. Alanine aminotransferase level was significantly higher in M10 than in the control group. Glucose level was significantly lower in B10 than in the control group. These results suggest that BSF and MW can be used as FM substitutes. However, considering feed conversion ratio and AST level, MW availability is thought to be lower than that of BSF, and feeding fish with a diet containing MW for an extended period is thought to adversely affect fish growth.

• Journal of Aquaculture
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• v.8 no.2
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• pp.133-140
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• 1995

Olive flounder (Paralichthys olivaceus) larvae of pre-metamorphic and early metamorphic stage were treated with different concentrations of triiodothyroxine $(T_3)\;and\; thyroxine\;(T_4)$ by immersion (0.02, 0.04, 0.08 and 0.16 ppm) for 11 days. Although $T_3$ was more potent than $T_4,\;both\;T_3\;and\;T_4$ accelerated the settlement time of fish larvae. Duration upto complete settlement in hormone-treated groups was significantly shorter than that in controls. Survival of hormone-treated groups at the pre-metamorphic stage decreased as hormone concentrations increased, however groups treated at the early metamorphic stage were not differ from control. Growth rates of groups treated with high concentration of hormone were slightly lower than that of control except 0.02ppm $T_4$ treated group.

• Korean Journal of Ichthyology
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• v.19 no.4
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• pp.350-359
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• 2007

The egg development and morphological change of larvae and juveniles of the starry flounder, Platichthys stellatus were observed in laboratory. Fertilized eggs of the species, 1.09~1.19 mm (mean $1.13{\pm}0.03mm$, n=50) in diameter, were floating, colorless, transparent in shape and lacked in oil globules. The eggs hatched out 121 hours after fertilization at water temperature $8.2{\sim}11.2^{\circ}C$. The size of the hatched larvae were 2.58~2.89 mm (mean $2.67{\pm}0.09mm$) in total length, their mouth and anus were not open yet and myotome number was 14+27=41. Melanophore and xanthophore appeared on the notochord and digestive organ and the margin of membrane fin, on the yolk sac and eyes were lacking in pigment cells. 5 days after hatching the larvae attained 4.30~4.97 mm (mean$4.74{\pm}0.21mm$) in TL, and their mouth and anus were open. 10 days after hatching the larvae transformed to postlarval stage and they were 4.67~5.75 mm in TL (mean $5.30{\pm}0.31mm$), and absorbing the yolk completely. Feeding activity increased as the mouth became larger. At 23 days, the larvae attained 6.69~8.82 mm in TL (mean $7.85{\pm}0.75mm$), and the right eye was started moving to the left side of the head. At 52 days, the juveniles attained 10.99~17.06 mm in TL (mean $13.50{\pm}1.67mm$). The right eye was moved completely onto the left side. All of the fins had completed set of the fin rays (D. 64~67: A. 45~51: P. 11: V. 6: C. 19).

• Journal of fish pathology
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• v.33 no.1
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• pp.7-14
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• 2020

A disease that manifested severe anemia of the gills occurred in the olive flounder (Paralichthys olivaceus), which was cultured for 5-6 months with a recirculation water system in the laboratory. Microscopic observations showed immature parasite in the gills and mature adults in the oral cavity. The matured parasite was 5.60-9.32 (7.42) mm in total length, with 4 pairs of clamps on the pedunculated haptor, which was separated from the body proper by a long isthmus. From the morphological observations of the larvae, it was identified as Neoheterobothirum hirame belonging to the monogenea. The average hematocrite of infected fish was 10.3 ± 2.8%, significantly lower than that of normal flounder 31.4 ± 4.2%. Histopathologically, fish infected with N. hirame exhibited reduced numbers of erythrocytes in blood vessels of the gill filament and lamellae, reduced red pulp area of the spleen, and hepatocyte atrophy. From the above results, the cause of severe anemia in olive flounder was identified as N. hirame infection. This study shows an example where the growth of pathogens can be a problem in the recirculation system due to low water exchange rate.

• Journal of fish pathology
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• v.8 no.1
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• pp.57-67
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• 1995

Twenty-four hours, acute toxicity and the histopathological effect of formaline to flounder, Paralichthys olivaceus larvae were examined. The $LC_{50}$ values obtained to farmaline were 2,520 ppm in 1 hour treatment. 1.610 ppm in 2 hours treatment, 868 ppm in 4 hours treatment and 141 ppm in 24 hours treatment. Many pathological features such as hypertrophy of mucous and epithelial cells in secondary gill lamella, hyaline droplet degeneration of tubular epithelial cells in the proximal convoluted segment of renal tubules, focal or massive necrosis in liver cells and pycnotic nucleus in heart cells were recognized. The above results were discussed in relation to the application of formaline as therapeutic agent in flounder disease.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.140-146
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• 2008

Marine ecotoxicological standard method using fish larvae was established with the standard test species of Oryzias latipes(Japanese Medaka) and Paralichthys olivaceus(flounder) and with the 7 day $LC_{50}$ as endpoint. Test method referred to the USEPA(1994) with the replacement of test species found in the Korean water. Standard test species were selected in terms of the species supply and ecological importance in Korean waters. Japanese medaka can be reared with small tanks in the lab and has wide tolerance on salinity, and flounder eggs can be easily obtained from commercial fish hatcheries. General conditions for larval fish toxicity test are as follows. The possible salinity ranges for toxicity test were $0{\sim}35\;psu$ for medaka and >20 psu for flounder. Test type was designated as static non-renewal test if the dissolved oxygen in the test chamber does not fall below 4.0 mg/L. Ages of test species were selected as 7 days after hatched for medaka(about 5 mm TL) and 25 days for flounder(about 10 mm TL) because of the low natural mortality after these periods. Test can be accepted when the survival rates are over 80% in control. Also, species sensitivity on standard reference materials(copper, cadmium or zinc) must be provided with the toxicity test results.

• Journal of Aquaculture
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• v.9 no.3
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• pp.287-291
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• 1996

[ $F_2$ ] generation of gynogenetic diploids were produced in olive flounder, Paralichthys olivaceus, by brother-sister mating with full-sibling gynogenetic diploids ($F_1$). The induced ovulations and spawnings were conducted by using intraperitoneal injections of HCG (2,000 IU/kg body weight) with photoperiod controls. Floating rates of artificially ovulated eggs were ranged from 22.9 to $65.7\%$. Fertilization and hatching rates were ranged from 69.0 to $86.2\%$ and 36.8 to $85.8\%$, respectively. All of those three rates between two experimental groups were not significantly different (P>0.05). Average survival rates of $F_2$ generation of 40-day-old 효nogenetic diploid larvae were slightly lower than those of controls (P<0.05), however growth rates were much higher than those of their diploid controls.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.1-5
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• 2009

This study was to investigate the habitat conditions and growth of right eye flounder (Kareius bicoloratus) in the Saemangeum Reseorvoir during 1995$\sim$2007. The planktonic larvae of K. bicoloratus appeared in early March, and then the juveniles started the benthic life in the tide-pools inside the reservoir, being 1.5$\sim$2.5cm in total length in early April and 6.0$\sim$7.2cm in mid-July. This species was not collected in the tide-pools after July, indicating that the juveniles began to move to outer seas for growing. When the tide barrier of Saemangeum was constructed, the juveniles of K. bicoloratus decreased as the tidal pools were covered continuously, then they could not be collected after 2005. Thus, it is concluded that the environmental change has taken important influence on distribution and spawning of K. bicoloratus since the reservoir was constructed.