• Journal of Aquaculture
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• v.10 no.1
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• pp.77-85
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• 1997

A 6-week feeding trial was conducted to determine the nutritional value of various dietary animal protein sources in juvenile Koran rockfish. White fish meal (WFM), flounder muscle meal (FMM), blood meal (BM), casein & gelain (CG), egg white albumin (EWA) and squid liver powder (SLP) were used as the animal protein sources, Crude protein content and available energy of the experimental diets were 50% and 15.9 kJ/g, respectively. There were significant differences among all dietary groups in weight gain (WG), feed efficiency (FE), and protein effiency ratio (PER). WFM and FFM were the best animal protein sources among the dietary groups. FMM diet had significantly higher (P<0.05) WG, FE, and PER values than those of fish fed the WFM diet. WG, FE, PER, and specific growth rate (SGR) values of fish fed BM diet were significantly higher (P<0.05) than those of fish fed EWA diet. Significant differences were found in whole body composition, hemoglobin (Hb), hepatosomatic index (HSI), and hematocrit (Ht). These results showed that low-temperature processing of lyophilized flounder muscle meal resulted in superior performance of rockfish relative to the other evaluated animal protein sources.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.245-251
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• 1998

A 10-week feeding experiment was conducted to determine the influence of several minerals from dietary mineral premix on growth and body composition in juvenile Korean rockfish. Three replicate groups of fish Initially averaging 4.2 g were fed one of the ten experimental diets. Korean rockfish muscle and casein as protein sources were used in the basal diet, and deleted one of each mineral (P, Ca, Zn, Mg, Fe, K, Mn, Se or all) in the control mineral premix, Weight gain, feed efficiency and nutrient retention in fish fed the diet not containing mineral premix were significantly lower than those in fish fed other diets (P<0.01). Weight gain in fish fed the diets deleted each mineral (P, Ca, Zn, Hg, Fe, K, Mn or Se) was lower than that of control diet (P<0.01), Feed efficiency and protein retention in fish fed the diets deleted each of P, Ca, Zn or Mn were lower than those ot control diet (P<0.01). Daily feed intake and lipid retention were not affected by dietary mineral premixes ( P>0.01). Proximate analysis and mineral contents in the whole body, muscle, liver or bone of fish fed the diets deleted each mineral were not different to control diet ( P>0.01). The data obtained in this study indicate that each of the P, Ca, Zn, Mg, Fe, K, Mn or Se is essential for normal growth of Korean rockfish.

• Journal of Aquaculture
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• v.20 no.1
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• pp.47-50
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• 2007

The primordial germ cells of the oblong rockfish, Sebastes oblongus were buried under fibrous mesenchymal tissues between gut and mesonephric duct of pre-larva with 4.0 mm total length (TL) at 1 day after the parturition. In the juvenile of 22.0 mm TL at 71 days after the parturition, the gonad composed of a large number of gonial cell and formed of cavity along the lateral side of the gonad, differentiated to the ovary. At this time, the gonad formed seminiferous tubules by somatic cells, was differentiated to the testis. The smallest oblong rockfish that possessed primary oocytes was about 42.1 mm TL at 141 days. Spermatogonia remained quiescent until most fish were over 42.1 mm TL at 141 days. The oblong rockfish the differentiated directly into male or female without an intermediate female phase at the early indifferentiated stage. Therefore, the oblong rockfish belongs to the differentiated type of gonochoristic teleosts.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.3
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• pp.250-256
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• 2009

A 8-week feeding trial was conducted to investigate the effects of dietary supplementation of Kugija (Lycium chinense) on the growth and immunological response in juvenile Korean rockfish (Sebastes schlegeli). Six experimental diets were supplemented with Kugija at 0, 0.1, 0.5 1.0, 3.0 and 5.0% ($K_0,\;K_{0.1},\;Ko_{0.5},\;K_{1.0},\;K_{3.0},\;K_{5.0}$) on a dry-matter basis. After 2 weeks, triplicate groups of 30 fish initially averaging 3.36$\pm$0.2 g (mean$\pm$SD) were randomly distributed into the aquarium and were fed one of the experimental diets for 8 weeks. By the end of the 8-week feeding trial, fish fed the $K_{0.5}$ and $K_{1.0}$ diets exhibited a higher weight gain and specific growth rate than fish fed $K_0$ and $K_{0.1}$ diets (P<0.05). Feed efficiency of fish fed the $K_{0.5}$ diet showed significant higher value than that of fish fed the $K_0$, $K_{3.0}$ and $K_{5.0}$ diets (P<0.05). Hepatosomatic index of fish fed the $K_{0.5}$ diet was significantly higher than that of fish fed the $K_{0.1}$ and $K_{5.0}$ diets (P<0.05). Hematocrit of fish fed the $K_{0.5},\;K_{1.0}$ and $K_{5.0}$ diets was significantly higher than that of fish fed the $K_0$ diet (P<0.05). Glutamic oxaloacetic transaminase of fish fed the $K_{0.5},\;K_{1.0},\;K_{3.0}$ and $K_{5.0}$ diets was significantly lower than in fish fed the other diets (P<0.05). Glutamic pyruvic transaminase activity of fish fed the $K_{3.0}$ diet was significantly lower than those of fish fed the $K_0$ and $K_{0.1}$ diets (P<0.05). However, there was no significant difference in the activity of the transaminase in fish fed the $K_{0.5}\;K_{1.0},\;K_{3.0}$ and $K_{5.0}$ diets. Lysozyme activity of fish fed the $K_{0.5}$ and $K_{1.0}$ diets was significantly higher than that in fish fed the $K_0$ and $K_{0.1}$ diets (P<0.05). Respiratory burst activity of fish fed the $K_{3.0}$ diet was significantly higher than those of fish fed the $K_0$ and $K_{0.1}$ diets (P<0.05). However, there was no significant difference in respiratory burst activity of fish fed the $K_{0.5}\;K_{1.0},\;K_{3.0}$ and $K_{5.0}$ diets. Fish fed Kugija showed lower early mortality than fish fed a Kugija-free diet upon challenge with Vibrio ordalii. The results suggest that feeding of Kugija (Lycium chinense) enhances growth, non-specific immunity and disease resistance in juvenile Korean rockfish.

• Journal of Aquaculture
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• v.9 no.2
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• pp.159-166
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• 1996

A feeding experiment was conducted using juvenile Korean rockfish (Sebastes schlegeli) to evaluate supplemental vitamin premix in a test diet containing fish meal as protein source for nutritional study. Four vitamin premixes were prepared by adjusting different quantity and combination of vitamins. Each vitamin premix contained (mg/kg diet) : premix-1 : ascorbic acid, 2666 ; a-tocopheryl acetate, 417 ; thiamin, 60 ; riboflavin, 200 ; pyridoxine, 40 ; niacin, 800 ; Ca-D-pantothenate, 280 ; myo-inositol, 4000 ; D-biotin, 6 ; folic acid, 15 ; p-amino-benjoic acid, 400 ; mennadione, 40 ; A, 16 ; $D_3$, 0.1 ; choline chloride, 8000 ; cyanocobalamin, 0.09 ; premix-2 : ascorbic acid, 270 ; a-tocopheryl acetate, 189 ; thiamin, 13.5 ; riboflavin,, 27 ; pyridoxine, 13.5 ; niacin, 135 ; Ca-D-pantothenate, 135 ; myo-inositol, 135 ; D-biotin, 1. 4 : folic acid, 4.9 ; mennadione, 5.4 : A, 5.4 ; $D_3$, 2.2 ; choline chloride, 3000 ; cyanocobalamin, 0.05 ; premix-3 : ascorbic acid, 570 ; a-tocopheryl acetate, 107 ; thiamin, 20 ; riboflavin, 14.3 ; pyridoxine, 14.3 ; niacin, 71,3 ; Ca-D-pantothenate, 57 ; myo-inositol, 456 ; D-biotin, 0.7 ; folic acid, 2.9 ; p-aminobenjoic acid, 285 ; mennadione, 5.7 ; A, 5.7 ; $D_3$, 1.1 ; choline chloride, 1500 ; cyanocobalamin, 0.03 ; premix-4 : ascorbic acid, 190 : a-tocopheryl acetate, 36 ; thiamin, 6.7 ; riboflavin, 4.8 ; pyridoxine, 4.8 ; niacin, 23.8 ; Ca-D-pantothenate, 19 ; myo-inositol, 152 ; D-biotin,0.2 ; folic acid, 1 ; p-aminobenjoic acid, 95 ; mennadione, 1.9 ; A, 1.9 ; $D_3$, 0.4 ; choline chloride, 500 ; cyanocobalamin, 0.01. Triplicate groups of the 50 fish averaging 4.25 g were fed one of four isoproteic ($47\%$) and isolipidic ($9\%$) experimental diets to satiation twice a day for 10 weeks. Weight gain, feed efficiency and protein retention in fish fed the diet with vitamin premix-1 were significantly higher than those in fish fed the other diets (P<0.05). Moisture, protein and lipid contents of muscle and whole body were not affected by different dietary vitamin premix (P>0,05). These results indicate that premix-1 can be used to adequate supplemental vitamin premix in test diet containing fish meal as protein source for juvenile Korean rockfish.

• Journal of Aquaculture
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• v.21 no.2
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• pp.82-88
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• 2008

A 12-week feeding trial was conducted to investigate the effects of dietary supplementation of probiotics as a feed additive for juvenile Korean rockfish Sebastes schlegeli. Four experimental diets supplemented with no probiotic(Control), Bacillus polyfermenticus(BP), Bacillus licheniformis(BL) or Bacillus polyfermenticus plus Saccharomyces cerevisiae(BP+SC) at $1.0{\times}10^7$ CFU/kg diet as a dry-mater(DM) basis were prepared by mixing with a basal diet. After 12 weeks of the feeding trial, fish fed BP+SC diet showed significantly higher weight gain(WG), feed efficiency(FE), specific growth rate(SGR) and protein efficiency ratio(PER) than those of fish fed control diet(P<0.05), however there were no significant differences in WG, FE, SGR and PER among fish fed the BP, BL and BP+SC diets. Fish fed BP and BP+SC diets showed significantly higher condition factor(CF) than that of fish fed control and BL diets. Fish fed BP, BL, BP+SC diets showed significantly higher hepatosomatic index(HSI) than that of fish fed control diet, however there was no significant difference in HSI among fish fed BP, BL and BP+SC diets. Fish fed BP+SC diet showed significantly lower serum glucose than that of fish fed control diet, however there was no significant difference in serum glucose among fish fed BP, BL and BP+SC diets. Fish fed BP+SC diet showed significantly higher respiratory burst activity(NBT assay) than that of the fish fed control and BL diets, however there was no significant difference in NBT assay between fish fed BP and BP+SC diets. Fish fed BP and BL diets showed significantly higher lysozyme activity than that of the fish fed control diet, however there was no significant difference in lysozyme activity among fish fed BP, BL and BP+SC diets. Fish fed BP and BP+SC diets showed significantly lower cumulative mortality than that of the fish fed control diet, however there was no significant difference in cumulative mortality among fish fed BP, BL and BP+SC diets after the challenge test. From these results, dietary B. polyfermenticus, B. licheniformis and B. polyfermenticus plus S. cerevisiae supplementation in juvenile Korean rockfish diet could enhance growth performances, non-speicific immunities and a higher resistance against the specific pathogen.

• Journal of Aquaculture
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• v.17 no.2
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• pp.122-127
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• 2004

On protein equivalence base, fishmeal (FM) was replaced by lysine cell mass (LCM) in selected different diets in Korean rockfish, Sebastes schlegeli (Hilgendorf) Eight experimental diets were formulated to contain 100% FM (LC $M_{0}$), 90% FM+10% LCM (LC $M_{10}$),80% FM+20% LCM (LC $M_{20}$), 70% FM+30% LCM (LC $M_{30}$), 60% FM+40% LCM (LC $M_{40}$ ), 70% FH+30% LCM+lysine (LC $M_{+Lys}$), 60% FM+40% LCM+lysine (LC $M_{40+Lys}$), and 50% FM+50% LCM+lysine (LC $M_{50+Lys}$). Experimental individuals of the fish (12.6 g) were randomly fed on one of the experimental diets. After 6 weeks of feeding trial, weight gain (WG) and feed efficiency (FE) of fish fed LC $M_{0}$ diet was significantly (P〈0.05) higher than those of fish fed LC $M_{20}$, LC $M_{30}$, LC $M_{40}$ , LC $M_{30+Lys}$, LC $M_{40+Lys}$, and LC $M_{50+Lys}$ diets, however, there was no significant difference in WG of fish fed LC $M_{0}$ and LC $M_{10}$ diets. Supplementation of lysine has no effect on WG. There was no significant difference in condition factor (CF) of fish fed LC $M_{0}$, LC $M_{10}$ and LC $M_{20}$ diets. Hemoglobin (Hb) of fish fed LC $M_{0}$, LC $M_{10}$, LC $M_{20}$, LC $M_{30}$, LC $M_{40}$ , LC $M_{30+Lys}$, and LC $M_{40+Lys}$, diets were not significantly different from each other. No significant differences were observed in hematocrit (PCV) and hepatosomatic index (HSI) among all dietary treatments. Apparent digestibility of dry matter (ADM) and protein (ADP) of diets significantly decreased with increase in dietary LCM level, though there was no difference in ADM and ADP between LC $M_{0}$ and LC $M_{10}$. These results indicate that LCM could replace up to 10% of fishmeal in Korean rockfish diets.ish diets.iets.ish diets.s.ish diets.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.158-159
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• 2003

Although the sub-chronic toxic effects of metal on fishes are well documented, that is mostly in fishes exposed to waterborne metal but few studied have been conducted on the effects of dietary metal (Handy, 1996). The realization that dietary uptake of metal is a major cause of long-term contamination in wild fish has renewed interest in the nutritional and toxicological effects of metal in the food of fishes (Handy, 1996). (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.44-50
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• 1996

Sex differentiation in the rockfish, Sebastes schlegeli, was studied by using a histological method for the appearance of primordial germ cell, formation of primitive gonad and differentiation of female and male. The primordial germ cells were buried under fibrous mesenchymal tissue between gut and mesonephric duct of pre-larva with a total length (TL) of 6.3 mm at 2 days after parturition. In juvenile of TL $5.2\~5.9cm$ at 65 days after parturition, the gonad composed of a large number of genial cell and formed of cavity along the lateral side of the gonad, differentiated to the ovary. At this time, the gonad formed seminiferous tubules by somatic cells, differentiated to the testis. In juvenile of TL $7.0\~7.2cm$ cm at 115 days after parturition, gonads divided into testis contained pigment cell and ovary absent pigment cell. S. schlegeli differentiated directly into male or female without an intermediate female phase at early indifferentiated stage. Therefore, S. schlegeli belongs to the differentiated type of gonochoristic teleosts. At 350 days after parturition, sex ratio was approximately 1 : 1(p>0.05).

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.236-243
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• 2023

This study aimed to investigate the survival rates, hematologic responses, and histological responses of juvenile Korean rockfish (Sebastes schlegelii) exposed to artificial increase of water temperature. The water temperature was incrementally raised from the initial 23℃ to 26℃, 28℃, 30℃, and 31℃, with a 1℃ increase every 24 hours. The fish were exposed to each water temperature setting for a period of seven days. No mortality was observed at 26℃ and 28℃. However, at 30℃, mortality began on the 4th day of exposure, with an overall survival rate of 1.5% at the end of the seventh day. At 31℃, mortality occurred as early as the first day of exposure, and all fish had perished by the second day. Plasma cortisol and glucose concentrations increased as water temperature rose, with a significant decrease observed at 31℃. No significant difference in plasma GPT concentration was observed across the various experimental temperatures. In contrast, plasma GOT concentration significantly increased at 31℃. Histological examination revealed that both the liver and gills exhibited normal histology at the initial temperature of 23℃ and at 26℃. However, at 28℃ hepatocellular hypertrophy and gill lamellar epithelial hyperplasia and epithelial cell lifting were observed. At 30℃, hepatocellular condensation and gill lamellar fusion were noted. Finally, at 31℃, severe histological changes were observed, including hepatocellular necrosis, liver congestion, and gill filament necrosis.