• Applied Microscopy
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• v.41 no.2
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• pp.123-128
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• 2011

The micropyles on the prefertilized and artificial fertilized eggs of Epinephelus fasciatus were investigated using scanning electron microscope (SEM). The micropyles ($6.6{\pm}0.41\;{\mu}m$) of E. fasciatus eggs were found in the animal pole and theirs shape were observed as a flat crateriform of cylindrical shape. The micropylar vestibule arranged by 6~7 thickened spiral annuli on the ridge and contributed to differentiate and form fertilization cone for blocking to polyspermy by presenting swollen vestibule structure. As E. fasciatus eggs was pelagic, so chorionic surface was an uneven structures such as circular and fillar form nodules. Especially, various pores (0.15~0.55 ${\mu}m$, 230~270 pores) distributed at the only around micropyles, those pores radiately exhibited regular projection structures showing gill filament-shape. These ultrastructural characters of E. fasciatus eggs can be utilized in a taxonomical cue of grouper species.

• Applied Microscopy
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• v.42 no.2
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• pp.61-66
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• 2012

Ultrastructural characteristics of blacktip grouper, Epinephelus fasciatus spermatozoa were investigated using transmission and scanning electron microscopy. The spermatozoa of E. fasciatus consisted of a spherical head part, a midpiece with cytoplasmic canal entrance and a flagellum with lateral fins. Internal ultrastructurally, the nucleus contains high electron dense chromatin having granular particles and has no acrosome. The centriolar complex lies outside of the nuclear fossa and it is connected by the osmophilic filaments. Also the osmophilic filaments connect between the centriolar complex and the nuclear membrane. The midpiece contains eight to nine spherical mitochondria, cytoplasmic canal and necklaces. The flagellum has a typical 9+2 axonemal structure. The lateral fins contain vesicles and a typical 9+2 axonemal structure. Consequently this study contributes to comparative grouper spermatology and provide useful systematic taxonomic characters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.847-852
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• 2014

The aim of this study was to investigate the effects of stocking density and water temperature in the rearing of the longtooth grouper Epinephelus bruneus. Juvenile fish [mean body weight (BW)=$6.9{\pm}1.1g$] were raised for 6 weeks, in four density groups of 0.25, 0.5, 0.75, and 1 individuals/L. There were no significant differences in weight gain (WG) or specific growth rate (SGR) among the density groups; however, both WG and SGR tended to be higher in the low density group. After 6 weeks of rearing in temperature-controlled water ($23.6{\pm}0.8^{\circ}C$) and ambient temperature water ($19.6{\pm}1.8^{\circ}C$), there were no significant differences in WG or SGR values, but both tended to be higher in the temperature controlled water. The feed efficiency (FE) and daily feed intake (DFI) and WG values were also higher in the temperature-controlled water than in the ambient temperature water. WG values were lower at lower water temperatures. The same pattern was observed for SGR, FE, and FI, all of which exhibited lower values at lower temperatures. In particular, WG, SGR, and FE values all tended to decrease at the $16^{\circ}C$ water temperature. The effects of water temperature on 1-year fish (mean BW = $387.6{\pm}30.2g$) and 3-year fish (mean BW = $1,338.3{\pm}73.8g$) were similar to those of the juvenile fish (0-year fish).

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.260-266
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• 2016

We determined the morphologic characteristics (body weight and abdomen inflation degree) of the mother fish of sevenband grouper, Epinephelus septemfasciatus producing the healthy eggs. Experimental fish were chosen from the reared fish in the sea cage for 6 years. The fish were divided into four size groups by body weight: 4.0~5.0, 5.0~6.0, and 6.0~7.0 kg and four stages (I~IV) by the abdomen inflation degree. After hormone treatment, we observed the ovulation amount of induced eggs, rate of buoyant, fertilization, embryonic survival, and hatching. Egg and oil globule diameter was measured. In order to observe gonadal development, we calculated gonadosomatic index (GSI) and conducted its historical analysis. The ovulation occurred from all experimental fishes over 5.0 kg. The rate of buoyant, fertilization, and embryonic survival was the highest in 6.0~7.0 kg. Hatching rate was the highest in 5.0~6.0 kg. Stage I and II did not induce ovulation. GSI was $0.31{\pm}0.10%$ in stage I, $0.74{\pm}0.25%$ in stage II, $4.68{\pm}0.40%$ in stage III and $6.86{\pm}0.12%$ in stage IV. The rate of buoyant, fertilization, embryonic survival and hatching was the highest in stage III.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.229-238
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• 2016

This study aims to investigate egg quality and amino acid composition of buoyant and non-buoyant eggs and evaluate egg quality of sevenband grouper, Epinephelus septemfasciatus. Amino acid analysis of eggs was conducted to investigate what elements were necessary for the survival and good quality of egg depending on farming condition and different diet. We analyzed amino acid from buoyant eggs and non-buoyant eggs, farming conditions (tank and sea cage), and different dietary conditions (formulated feed, formulated feed+raw fish-based moist pellets, and raw fish-based moist pellets). Egg quality was the best in a sea cage and when raw fish-based moist pellets (MP) were fed. In addition, egg quality with formulated and MP was better than that with formulated feed. As a result of amino acid analysis of eggs, buoyant eggs were containing more free amino acid than non-buoyant eggs. Also, eggs with MP were containing more free amino acid than those with formulated feed and MP. Eggs with mixed formulated feed and MP were containing more free amino acid than formulated feed. In conclusion, amino acid was helpful to improve egg quality, and egg quality can be controlled by farming conditions and feed.

• Journal of Aquaculture
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• v.10 no.4
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• pp.473-483
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• 1997

Yolk resorotion and commencement of external feeding in larvae of red spotted grouper, Epinepheus akaara were studied to understand the high mortality of larvae. Consumption of yolk was higher than that of oil globule for the first 24hs after hatching. The resorption rates of yolk and oil globule increased with the increase of temperature. The time yolk was comsumed up to 99% was 84hs after hatching in 23~$25^{\circ}C$,72hs at ~$27^{\circ}C$, and 60hs in 29~~$31^{\circ}C$, while the time for oil globule was 96hs in 23~$25^{\circ}C$, 84hs at $27^{\circ}C$, and 60hs in 29~$31^{\circ}C$. The relationship between mouth openning time (Y) and water temperature (X) was repersented as a linear regression, Y=-2.53X+118.4, (r2=0.89). In 72~96hs after hatching, upper jaw sizes of the larvae reached around 0.114 mm. By the time the larvae comsumed most of the yolk and oil globule, and started external feeding. The relationship between upper jaw length (Y) and total length (X) was represented as a linear regression, Y=0.139X-0.165, (r2=0.88). Rotifer was not found in the guts of larvae before 72hs after hatching at $28^{\circ}C$, when larvae resorbed their yolk and oil globule over 99%. But, at 96hs after hatching, about 33% of the larvae had the rotifer in their guts. Delayed feeding experiments revealed that the earlier food supply within 84hs after hatching showed the better survival rates for the larvae. The larvae fed at 96hs after hatching died all within 120hs.

• Journal of Aquaculture
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• v.10 no.4
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• pp.463-472
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• 1997

Floating and hatching rates, size and survival activity index(SAI) of spawned eggs of red spotted grouper, Epinephelus akaara were studied to understand egg qualities during the spawning periods in 1992, 1993 and 1995. The fish spawned from mid-July to mid-August when temperature ranged 23~$28^\circC$. Floating, fertilization and hatching rates were higher in the eggs from early to middle than those from late during the spawning period. SAI ranged 1.8~9.6, and it was closely related to survival rate until mouth operning time (SMOT). Egg diameter decreased gradually with the time of spawning, while diameter of oil globule was constant during the spawning periods. Induced spawnings were carried out with one injection of HCG over 5, 000 IU/kg body weight. Floating, fertilization and hatching rates of the induced spawning eggs were higher than those of untreated ones. Thus, induced spawning method with HCG was recommended for collecting fertilized eggs in bulk. Optimal time for the collection of high quality eggs was supposed to be from early to middle during the spawning periods. Considering that egg qualities were vulnerable within the period, hatchability, incidence of malformed larvae, SMOT and SAI were factors to be considered together to get good quality of eggs.

• Journal of Marine Life Science
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• v.4 no.1
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• pp.38-43
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• 2019

The deformity occurring at the early developmental stage of red spotted grouper (Epinephelus akaara) causes detrimental effects on the process of juvenile production. In this study, we have compared the expressions of several key genes (insulin like growth factor 1: IGF-1, bone morphogenic protein 4: BMP4, peroxisome proliferator-activated receptors γ: PPARγ, matrix Gla protein: MGP) for morphogenesis between normal and 2 types (cephalic and jaw) of deformed juvenile fish. Expression of these genes were investigated in the brain, liver and muscle of each group of fish (n=20) by real-time PCR. Expression of IGF-1 and BMP4 mRNA in the brain and liver showed significant difference between normal and deformed fish (p<0.05). However, no difference was observed in the expression of PPARγ and MGP mRNA between normal and deformed fish in any tissues. It seems certain that IGF-1 and BMP4 are associated with the state of deformity in juvenile red spotted grouper.

• Journal of Marine Life Science
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• v.7 no.1
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• pp.45-51
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• 2022

The profer salinity range for aquaculture of hybrid grouper (Epinephleus bruneus♀ × Epinephleus lanceolatus♂) were evaluated in terms of their survival, growth, feed intake and physiological responses after 30 days of exposure to different salinities (0 psu, 3 psu, 5 psu, 10 psu, 15 psu, 20 psu, 25 psu, 30 psu). Hybrid grouper all died at 0 psu salinity on the 4th day of exposure but all hybrid survived at a salinity of 5 psu or higher during the exposure period. Body length and weight increased above 5 psu salinity and the growth rate was the highest at 30 psu. Hybrid exposed to 3 psu did not eat the feed pellet. Feed intake did not show a significant difference between salinity 20 psu, 25 psu and 30 psu. Plasma osmolality of the juvenile hybrids exposed to different salinities was 341~368 mg Osmol/kg above 5 psu. The oxygen consumption rate was the highest at 30 psu with 163.6±22.3 mg O₂/kg fish/h. SOD, CAT and GSH-PX were significantly higher at 15 psu. Therefore, the critical salinity for survive of the juvenile hybrid was 5 psu, and the proper salinity for optimal culture was analyzed with 20~30 psu.

• Development and Reproduction
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• v.17 no.4
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• pp.369-377
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• 2013

The fertilized eggs of E. septemfasciatus are spherical and transparent with buoyancy at 790 to $890{\mu}m$ (average $821.8{\pm}2.0{\mu}m$) in diameter with 170 to $230{\mu}m$ oil globules (average $192.9{\pm}0.93{\mu}m$). Hatching began approximately 46 and 35 hours after fertilization at $22.0^{\circ}C$ and $25.0^{\circ}C$ water temperature, respectively. The average total length of newly hatched larvae was $1.75{\pm}0.03mm$. Most of the yolk and oil globules were absorbed within 3 to 4 days after hatching. The larvae reached 2.48 to 2.72 mm in total length, and their mouths and anuses opened at 3 to 4 days after hatching. In this time, the mouth diameters of the larvae were 0.209 to 0.238 mm. The larvae reached 3.24 to 4.15 mm in total length at 11 to 17 days after hatching, and began to metamorphose at the time the second dorsal and pelvic spines appeared and elongated. The abdominal cavity was densely lined with melanophores. The larvae reached 5.12 mm in total length at 24 days after hatching.