• 한국수산과학회지
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• 제42권4호
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• pp.344-348
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• 2009

This study was conducted to investigate effects of dietary lipid level on growth and body composition of juvenile red sea bream in low temperatures. Duplicate groups of fish (initial body weight of 79 g) were fed one of three isonitronic diets (47% crude protein) containing different lipid levels (10%, 17% and 22%) for 25 weeks during the winter season. Weight gain and survival of fish fed 17% lipid diet were significantly (P<0.05) higher than those fish fed the 10% or 22% lipid diet. Protein efficiency ratio, daily feed intake, condition factor, hepatosomatic index and viscerasomatic index were not affected by dietary lipid level, but feed efficiency of fish fed 10% lipid diet was significantly (P<0.05) lower than those fish fed the 17% or 22% lipid diet. Proximate composition of the whole body, liver, viscera and dorsal muscle were not significantly different among all groups except for crude protein content of dorsal muscle. The contents of 16:0, 18:0, 20:4n-3 and 20:5n-3 of the whole body were significantly (P<0.05) affected by dietary lipid level. The results of this study suggest that an increased dietary lipid level from 10% to 17% can improve growth of juvenile red sea bream in low temperature periods.

• Fisheries and Aquatic Sciences
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• 제16권1호
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• pp.57-61
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• 2013

I hypothesized that the manipulation of dietary nutrient contents including phosphorous could affect compensatory growth of juvenile olive flounder, Paralichthys olivaceus. Thirty fish averaging 34.8 g per tank were randomly chosen and distributed into 15 flow-through 180-L tanks. Three experimental diets were prepared: the control (C) diet, high protein and lipid (HPL) diet, and HPL diet with supplementation of calcium phosphate-monobasic (HPLP). Five treatments were prepared in triplicate: fish were hand-fed daily with the C diet twice a day for 8 weeks (C-8W); fish were starved for 1 week, and then fed with the HPL or HPLP diets twice a day for 7 weeks, and referred to as HPL-7W and HPLP-7W, respectively; and fish were starved for 2 weeks, and then fed with the HPL or HPLP diets twice a day for 6 weeks, and referred to as HPL-6W and HPLP-6W, respectively. The body weight of fish with C-8W, HPL-7W and HPLP-7W treatments was higher than fish with HPL-6W and HPLP-6W treatments on week 2, 4 and 6 after an initiation of the trial. At the end of the 8-week trial, fish with HPLP-7W and HPL-7W treatments overcompensated, as compared to fish with C-8W treatment. Full compensation was not achieved in fish subjected to the 2-week feed deprivation (HPL-6W and HPLP-6W treatments). Overall feed intake by fish was proportional to weeks of feeding. Feed conversion ratio of fish with HPLP-7W, HPL-6W and HPLP-6W treatments was higher than fish with C-8W treatment. The study showed that dietary supplementation of protein and lipid resulted in overcompensation of juvenile olive flounder subjected to a 1-week feed deprivation, but not a 2-week feed deprivation. Additionally, dietary supplementation of phosphorous did not further improve compensatory growth of fish.

• 한국수산과학회지
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• 제51권2호
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• pp.157-162
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• 2018

A feeding trial was conducted to investigate the effects of supplementation with four phosphorus (P) additives [mono-calcium phosphate (MCP), dicalcium phosphate (DCP), tricalcium phosphate (TCP) and magnesium hydrogen phosphate (MHP)] on the growth, feed utilization and whole body mineral composition of juvenile olive flounders Paralichthys olivaceus. A basal diet without P supplementation was prepared as a negative control and four supplemental P sources were added at a level of 2%. Triplicate groups of fish (initial mean body weight 11 g) were fed one of the experimental diets to apparent satiation twice a day, at 08:30 and 18:00 for 10 weeks. The final body weights of fish fed the experimental diets ranged from 29.4 g (DCP) to 34.2 g (MCP) and did not differ significantly (P>0.05) among treatments. Similar tendencies were found for all parameters including weight gain (%), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), feed intake (FI) and survival rate (SR). The hematocrit (%), hemoglobin (g/dL), serum inorganic P and whole body mineral composition did not differ significantly different (P>0.05) among the treatments. Therefore, dietary P addition is not necessary for juvenile olive flounder fed a fish meal-based diet.

• 한국수산과학회지
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• 제51권2호
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• pp.142-147
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• 2018

This study was conducted to investigate the effects of practical diets containing different seaweed powders on the growth and body composition of juvenile sea cucumber Apostichopus japonicus. Six experimental diets were formulated to contain 40% of the following seaweed powders: Sargassum thunbergii (ST), Undaria pinnatifida (UP), Ascophyllum nodosum (AN), Hizikia fusiformis (HF), fermented Laminaria japonica (FLJ), and fermented Hizikia fusiformis (FHF). Sea cucumbers (30 per tank; initial mean weight $0.4{\pm}0.01g$) in three replicates of six groups were fed one of the six experimental diets for 15 weeks. Survival in all groups was 83-93%, with no significant differences among the experimental groups. The specific growth rates of the sea cucumbers fed the ST and UP diets were significantly higher than those of sea cucumbers fed the HF, FLJ, and FHF diets, but did not significantly differ from those of sea cucumbers fed the AN diet. The results of this study suggest that S. thunbergii, U. pinnatifida, and A. nodosum could be useful sources of seaweed powder for practical diets of juvenile sea cucumber.

• 한국수산과학회지
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• 제50권6호
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• pp.756-761
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• 2017

This study investigated the growth of juvenile mandarin fish Siniperca scherzeri, reared at high water temperatures. Feed-trained juvenile fish were reared at four water temperatures: 27, 29, 31, and $33^{\circ}C$. The fish were fed to apparent satiation twice daily using pelleted diet. After 10 weeks of feeding trial, the survival exceeded 98% in all groups. The weight gain of fish reared at $31^{\circ}C$ was higher than for fish reared at the other temperatures. The feed efficiency and protein efficiency ratio of fish reared at 29 and $31^{\circ}C$ were higher than for the fish reared at 27 and $33^{\circ}C$. The daily feed intake of fish reared at 27 and $33^{\circ}C$ was higher than for the 29 and $31^{\circ}C$ groups. The whole body moisture content of fish reared at $33^{\circ}C$ was higher than in the $27^{\circ}C$ group. The whole body crude protein and lipid contents of fish reared at $27^{\circ}C$ were higher than in the $33^{\circ}C$ group. The results indicate that suitable rearing water temperature was $31^{\circ}C$ for optimal growth and feed efficiency of juvenile mandarin fish under the experimental conditions.

• Fisheries and Aquatic Sciences
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• 제17권1호
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• pp.95-103
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• 2014

This study was carried out to investigate the influences of dietary levels, ratios and sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the growth and fatty acid compositions of juvenile olive flounder Paralichthys olivaceus. Sixteen diets containing five levels of EPA (0.5%, 1.0%, 1.5%, 2.0%, and 4.0%), five levels of DHA (0.5%, 1.0%, 1.5%, 2.0% and 4.0%), three ratios of EPA/DHA (75/25, 50/50 and 25/75), two levels of squid liver oil (5% and 10%) and a control diet containing 5% soybean oil were hand-fed to triplicate groups of fish (average weight, $9.7{\pm}0.3g$) for 8 weeks. Survival, specific growth rate, feed efficiency and protein efficiency ratio of fish were not affected by dietary EPA and DHA levels or ratios. Also, the dietary treatment had no significant effect on the lipid and protein contents of muscle and whole body of fish. A corresponding increase in the EPA and DHA contents of fish occurred with increasing EPA and DHA levels in their diets. Our results suggest that juvenile olive flounder require a dietary EPA level of approximately 0.32% in the presence of 0.74% DHA for suitable survival and growth, and that EPA and DHA levels in fish muscle can increase to as much as 32% and 53%, respectively, of the total fatty acid content.

• 한국수산과학회지
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• 제55권4호
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• pp.443-448
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• 2022

Two long-term feeding trials were conducted to compare the effects on survival and growth of juvenile sea cucumber Apostichopus japonicus of experimental diets containing corn distillers dried grains with solubles, Squid Sepioteuthis sepioidea liver meal, and brown fish meal with a commercial die. In both first and second trials, two experimental diets and one commercial diet were assessed. After a 45-week feeding period in trial 1, survival did not differ significantly among groups. The final mean weight of sea cucumbers fed either experimental diet was significantly higher than that of sea cucumbers fed the commercial diet. After a 15-week feeding period in trial 2, survival and final mean weight of sea cucumbers fed either experimental practical diets was significantly higher than that of sea cucumbers fed the commercial diet. It was concluded that the experimental diets formulations can be used as a practical diet, and inclusion of corn distillers dried grains with solubles, squid liver meal, and brown fish meal can improve the growth of juvenile sea cucumbers.

• 한국수산과학회지
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• 제56권1호
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• pp.79-88
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• 2023

A 12-week feeding trial was conducted to evaluate the effect of different stocking densities on the growth, body composition, stress, antioxidant status, and immune responses of juvenile rainbow trout Oncorhynchus mykiss. Juvenile rainbow trout (32.2±0.5 g) were randomly placed in eight experimental tanks, each containing 2,000 L of water, at stocking densities of 150, 300, 600, and 1,200 individual/m³. The trout were assigned to four treatments (2.4, 4.8, 9.7, and 19.4 kg/m³) in duplicates. Following after the feeding trial, the fish cultured in the less dense group showed significantly higher growth and survival (P<0.05). In terms of proximate composition, the whole body crude protein and lipid contents were lower in the denser group (19.4 kg/m³). Regarding the antioxidant and immune responses, the fish reared in the relatively denser group exhibited lower lysozyme, immunoglobulin M, and superoxide dismutase levels. The stress indicators, glucose and cortisol, were significantly lower in the less dense group (2.4 kg/m³), while the denser group (19.4 km/m³) exhibited higher AST and ALP levels(P<0.05). The results showed that denser stocking has a crowding stress effect and negatively impacts growth and immune responses.

• 한국발생생물학회지:발생과생식
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• 제23권1호
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• pp.35-42
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• 2019

Fish shows great difference in growth rate between individuals during larval development and early growth. This difference seriously reduces the production efficiency in fish culture. Growth hormone (GH)/Insulin-like growth factor 1 (IGF1) system is said to play some pivotal roles in fish growth. In this study, we investigated differences of GH, IGF1 and GHR gene expressions in juvenile red spotted grouper (Epinephelus akaara) with different growth performance. Red spotted groupers were reared under the same environmental condition (water temperature $24{\pm}1^{\circ}C$, natural light) for 96 days after hatching. They were divided into 3 groups by size (fast growing, middle growing and slow growing groups: FGG, MGG, and SGG, respectively). RNA was extracted from the brain, liver and muscle tissues from each group, and target gene expression was examined by real-time PCR. In the brain with pituitary gland, expression of GH gene in FGG was significantly higher than the expression in SGG, but the expression of IGF1 and GHR genes in the muscle was highest in SGG. Difference of GHR and IGF1 mRNA in the liver between groups with different growth performance was less clear than that in other tissues, although level of IGF1 mRNA was higher in SGG than in MGG. These results suggest that hormonal governing of growth is not the same in fast growing and slow growing fish, and size grading could cause a shift of hormonal state and growth pattern in this species.

• 한국발생생물학회지:발생과생식
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• 제22권3호
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• pp.205-212
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• 2018

This study is to observe the developmental process of the larval skeleton according to the growth of the trident goby, Tridentiger obscurus belonging to the larvae and juveniles and use it as the basic data of the taxonomic study. 8 days after hatching, the parasphenoid was ossified with an average total length of 3.62 mm, and basioccipital began to ossify. Caudal vertebrae and neural spine ossified in vertebra. 17 days after hatching, the average total length of the long hairs was 4.32 mm, pterotic and epiotic were ossified, and interhyal and subopercle were ossified. 52 days after hatching, the average total length of the juvenile was 18.2 mm, and lateral ethmoid, hypohyal ossified, vertebrae were parapophysis, and epural bone was osseous to the bone.