• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.462-468
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• 2004

In order to evaluate adaptation to the environment in released fish, digestive organ and body composition were compared among 1-year old cultured (CUL), released (REL) and wild (WIL) Black Sea Bream, Acanthopagrus schlegeli. Hepatosomatic index (HSI) of the REL was significantly lower than those of the CUL and WIL fish, but intestine weight index (IWI) of REL was significantly higher than those of the CUL and WIL fish. There were no significant differences in stomach weight index (SWI) and condition facto. (CF) among those different fish groups. The number of pyloric caeca of the REL and WIL fish were 4, but the $30{\%}$ of CUL fish was 3 counts. The moisture content of whole body in the WIL fish was significantly higher than the CUL and REL fish, but significant lowest in the crude lipid of whole body. The content of moisture and crude protein of dorsal muscle were no significant differences among the CUL, REL and WIL fish, but crude lipid content of WIL fish was significantly lower than the CUL and REL fish. Moisture content of CUL fish in the liver was significantly lower than the REL and WIL fish, and crude lipid was significant lowest in the WIL fish. Amino acid content of dorsal muscle in the WIL fish was highest in the total amino acid, EAA and E/A ratio, and CUL fish was highest EAA and E/A ratio in liver. EPA content in dorsal muscle of WIL fish was lower than CUL and REL fish, and the REL fish was highest in DHA content of the fatty acid. EPA content in liver of WIL fish was lower than CUL and REL fish, and DHA content in REL and WIL fish was highest and lowest. Crude protein content of CUL and WIL fish in the scale was significantly higher than REL fish, but there were no significant differences in contents of crude lipid and ash. Ca and P of scale were formed most of mineral and content of P in CUL fish was significantly higher than those of REL and WIL fish. There were no significant differences in Mg, K, Na and S of scale, but CUL fish was significantly lower than REL fish in C1. The results suggest that difference of digestive organs and body composition concluded it from differences of inhabitation environment and feed formulations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.302-306
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• 2000

Gonad and blood samples were taken from cultured greenling (Hexagrammos otakii), and changes of steroid hormone levels in serum were examined in relation to the gonadosomatic index (GSI). GSI of female and male were not changed significantly between March and August and then began to increase from September showing the highest value in January. Hepatosomatic index (HSI) of female was the highest in December,'then decreased gradually until May. $Estradiol-l7{\beta} (E_2)$ level in blood of female reached to the highest level in December, then decreased rapidly in January. The level was maintained low until August and started to increase In September. Testosterone (T) level in blood of female was similar to trend of $E_2$ in female. $17{\alpha}2{\beta}-dihydroxy-4-pregnen-3-one (17{\alpha}20{\brta}-OHP)$ level in blood of female reached to the maximum in January, and then decreased rapidly from Febuary and maintained low until July. T level in blood of male reached to the highest value in December, and it started to decrease from January and maintained low until July, after then increased again, while $17{\alpha}20{\beta}-OHP$ level of male was similar to trend of female's.

• Journal of Aquaculture
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• v.11 no.2
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• pp.173-182
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• 1998

The study has been conducted to understand gonadal development and the effects of $17^{\alpha}$-methyltestosterone on sex inversion of the red spotted grouper, Epinephelus akaara. Fish were collected from Deukyand bay in the southern coast of Korea in August, 1996 and then they had been cultivated at the indoor tank until August, 1997. Gonad somatic index (GSI) in the females of both treated and control group began to increase from February when water temperature was rainse again, and reached the maximum value in August, whereas it had decreased from September adn thereafter maintained relatively low value until January. Unlike females, GSI in the male or intersex of treated groups decreased after June. Hepatosomatic index (HSI) of the control group tended to show the relatively low around Autumn, whereas it showed relatively highr value in April and June when the ovary was in the growing stage. Although the treated groups showed relatively higher value of the HSI than the control, hte paterns in monthly variation of HSI were similar to the control. Sexual change of the female grouper to the male was attempted by acceleration with oral administration of $17^{\alpha}$-methyltestosterone at the dose of 0.2 and 0.5mg/kg fish for 120days. Transitional hermaphroditic gonads were observed from the various size of groupers ranging 21.0 to 36.1 cm in total length, while the functional males could be induced from th individuals of 28.8 to 33.5cm in total length. This result indicated that larger groupers than 30cm in total length should be used for sex inversion to maleness with $17^{\alpha}$-methyltestosterone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.100-106
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• 2003

This study was conducted to investigate the supplementary effects of vitamin C and E to moist pellet on growth and body composition in juvenile olive flounder (Paralichthys olivaceus). Four groups of diet made : moist pellet (MP) diet group was used as the control group where the ratio of raw feed and commercial compound meal is 5:5 $(CP\;30\%,\;CL\;17\%),$ vitamin C added group (VC), vitamin I added group (VE) and vitamin C and I added group (VCE). The supplementary amount of vitamin C and E corresponded to 1000 mg/kg (dry wt.) and 220mg/kg (dry wt.), respectively. Vitamin C was destroyed $50\%$ and vitamin E was destroyed $20\%$ for manufacturing process. After 8 weeks feeding trial, weight gain was $121.9\%$ in MP group, while it ranged from 180.5 to $184.9\%$ in the VC, VE and VCE group. Feed efficiency was $71.\6%$ in MP group, whereas it ranged from 78.7 to $80.6\%$ in the VC, VE and VCE group, weight gain and feed efficiency of fish fed vitamin supplemented diets were significantly higher than control group and no significant difference among the vitamin added groups was observed (p>0.05). There were no significant differences in moisture, crude protein, crude lipid, crude ash, condition factor (CF), hepatosomatic index (HSI), and visceraweight index (VWI) of body composition. Hemoglobin (Hb) was $3.79\%$ in MP group, whereas $4.99\%$ in VC group, $4.55\%$ in VE group and $5.07\%$ in VCE group; Hb was significantly higher in the vitamin added groups than the control group (p<0.05). Vitamin C retention in liver was 18.1, 20.7, 46.6, 54.0 mg/kg in MP, VE, VC and VCE groups, respectively. Vitamin E retention in liver was 25.9, 53.8, 88.2, 124.5 mg/kg in MP, VC, VE and VCE groups, respectively. These results indicate that supplementation of vitamin C and E to moist pellet diet significantly improved growth and feed efficiency of olive flounder, and the mixed addition of vitamin C (1,000 mg/kg dry wt.) and vitamin E (220 mg/kg dry wt.) did not lead to the synergy effect.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.305-312
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• 1997

Juveniles of black seabream, Acanthopagrus schlegeli were fed with the diets containing 0, 10, 20, 50 and 100 ppm of 3,5,3'-triiodo-1-thyronine $(T_3)$ respectively to assess the effect of this hormone on skeletal development and the change of physiological conditions for 50 days. $(T_3)$ treatment lasted for initial 40 days. Fish were fed the prescribed diet by hand to satiation in $2\~4$ times per day. After an initial 40 days period, skeletal development and abnormality were examined, and after a 50 days period, food intake, hepatosomatic index (HSI), thyroid cell height (TCH) and body proximate composition were also examined. Although toed intake was not different among 0, 10 and 20 ppm, the food intake of black seabream fed with the diets containing 50 and 100 ppm of $T_3$was significantly lower than those of 10 ppm. After the initial 40 days of $T_3$ administration, $T_3$ increased the relative growth of operculum, head, caudal fin and pectoral fin to body length, resulting in severe morphological abnormalities at the highest dose. Black seabream treated with 50 and 100 ppm of $T_3$ had abnormal shapes such as lordosis and opercular curl. The HSI parameters were reversely correlation with the dietary concentration of $T_3$. After the initial 40 days of this experiment, atrophy of thyroid gland was observed in fish administered with 50 and 100 ppm of $T_3$. On the 50th day of this experiment, atrophy of thyroid gland was observed only in the group administered with 100 ppm of $T_3$, and no difference was observed on TCH among the rest fours of experimental groups. At the end of the experiment the whore body proximate analyses indicated that there were significant effects of $T_3$ level on moisture, protein, lipid and ash contents.

• Journal of Aquaculture
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• v.7 no.1
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• pp.63-76
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• 1994

The effects of different dietary lipids on growth, body chemical composition, and nutrient partition of the Korean rockfish (43 g of initial mean weight) were studied. Fish were fed three experimental diets containing 1) $4.5\%$ squid liver oil, 2) $1\%$ squid liver oil and $3.5\%$ beef tallow, and 3) $1\%$ squid liver oil and $3.5\%$ soybean oil. Growth and feed efficiency were detarmined during a 19-week feeding period at water temperature of $15.5^{\circ}C$, and at the end of which body chemical compositions were analyzed. Remained fish were fasted for 45 days, and four fish were taken at 6, 12 and 24 hours, and 3, 15 and 45 days after the fasting to determine tissue compositions and hematological changes. Growth, feed efficiency, protein and lipid retention efficiency, hepatosomatic index(HSI), viscerosomatic index (VSI), and chemical composition of whole body and dorsal muscle were not affected by the different dietary lipids. Liver moisture content of fish fed squid liver oil diet was higher than that of fish fed beef tallow or soybean oil diet. Liver lipid content of fish fed beef tallow diet was higher than that of fish fed the other diets. Fatty acid composition of dorsal muscle and liver were affected by the different dietary lipids ; high levels of 20 : 5n-3 and 22 : 6n-3 from fish fed the diet containing squid liver oil, 18 : 1 from fish fed the diet containing beef tallow, and high 18 : 2n-6 and 18 : 3n-3 from fish fed the diet containing soybean oil were observed. Both HSI and VSI of fish fed three diets decreased with time after the begining of starvation. Liver glycogen did not change during the first 15 days of starvation and decreased thereafter, and that was not affected by the different dietary lipids. Lipid and protein contents in the dorsal muscle of fish decreased up to 15 days of starvation and remained unchanged thereafter, these were not different from each other. Glucose, free fatty acid, triglyceride and phospholipid concentrations in Fish serum were varied for the first 15 days of starvation, after that the concentrations of fish serum remained relatively stable in all the treatment groups with prolonged starvation. The results indicate that Korean rockfish can utilize fish oil, animal fat or vegetable oil equally as energy source when n-3HUF A is adquate.

• Journal of Aquaculture
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• v.16 no.3
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• pp.190-195
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• 2003

Dietary optimum ratio of frozen raw fish and commercial compound meal (CCM) in moist pellet (MP) were investigated to improve the growth rate, and feed and economical efficiency in the flounder, Paralichthys olivaceus. Experimental fish (average body weight, about 48 g) were divided into 6 groups and each group was fed with raw fish (FRF), and MPs (ratio of raw fish and CCM=9:1, 8:2, 7:3, 6:4 and 5:5) for 10 weeks. The 9:1, 8:2, 7:3, 6:4, 5:5 groups showed no significant difference in weight gain as 203.5~217.3%, while the FRF group showed significantly low growth rate as 183.1%(P<0.05). The feed efficiency gradually increased with the increase in the ratio of CCM and was the highest in the 5:5 group as 89.7%. As a result of analysis of body composition after the experiment, moisture was significantly low in the 7:3 group (P<0.05) and crude protein was significantly low in the 9:1 group (P<0.05). The crude lipid increased as the ratio of raw fish increased, and it was the highest in the raw fish group (8.3%) and the lowest in the 5:5 group (4.6%). There were no significant difference in hepatosomatic index (HSI) and condition factor(CF) among the experimental groups. Visceralsomatic index (VSI) increased with the increase in the ratio of raw fish and was significantly high in the raw fish group as 5.49 (P<0.05). For the unit cost of feed, it was found that raw fish was economical when mackerel, a source of raw feed, was 400 won/kg, while the ratio of 5:5 was economical when it was more than 500 won/kg. Results of this study concluded that sole use of raw feed is not desirable in view of growth, environment and economy, and the 5:5 group showed highest effect under the least use of raw feed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.431-438
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• 2000

To clarify the annual reproductive cycle in a rockfish, Sebastes schlegeli, monthly changes in gonadosomatic index (GSI), hepatosomatic index (HSI) and histological feature of gonads and plasma levels of sex steroid hormones ($estradiol-l7{\beta},\;17{\alpha},\;20{\beta}-dihydroxy-4-pregnen-3-one,\;testosterone\;and\;11-ketotestosterone$) were investigated. The annual reproductive cycle in females could be divided into 5 periods as follows: 1) recovery period (June to September): serum level of $estradiol-l7{\beta}$ increased gradually; 2) vitellogenesis period (Septemer to february) : vitellogenic oocytes were obsewed, GSI sustained high value, and serum level of $estradiol-l7{\beta}$ increased; 3) gestation period (February-April): developing larva showed in the ovary, and serum levels of $17{\alpha},\;20{\beta}-dihydroxy-4-pregnen-3-one$ and testosterone increased; 4) partrition period (April to May) : larva were delivered, and value of GSI and serum levels of hormones decreased rapidly; 5) resting period (May to June) : value of GSI and serum levels of $estradiol-l7{\beta}$ and testosterone remained low. The annual reproductive cycle in males could be divided into 6 periods; 1) early maturation period (April to June): value of GSI and serum levels of hormones incresed gradually, cyst of spermatogonia incresed in number, and a small number of cyst of spermatocyte was observed; 2) mid-maturation perid (June to September); value of GSI and serum levels of hormones increased, and germ cells in many cysts were undergoing active sperrnatogenesis; 3) late maturation period (September to November) : value of GSI and serum levels of hormones remained high and spermatozoa were released into the lumina of the seminal lobules; 3) spermatozoa dischaging period (Nobember to December) : the lumina of the seminal lobules were enlarged and filled with mature spermatozoa; 4) degeneration period (December to Februauy)i value of GSI decresed and cyst of spermatocyte were decresed in number; 5) resting period (December to April) : no histological changes of testes were observed, and value of GSI and serum levels of hormones remained low. In November, the lumina of the seminal lobules were filled with mature spermatozoa and sperm masses were present in the ovarian cavity. Thus, copulation in this species occurred in November and December.

• Journal of Aquaculture
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• v.9 no.3
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• pp.265-278
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• 1996

A long-term (160 days) feeding experiment was conducted to evaluate effects of dietary soybean meal (SBM) on growth of rainbow trout (Oncorhynchus mykiss). Fish fed diets containing up to $46\%$ of SBM showed the same growth rates with control during the first 60 days (p>0.05). However, growth showed a gradual decrease with the culture period. At the end of 160-days experiment, fish fed diets with above $34\%$ of SBM showed a decrease in growth rate compared to the control group. Fatness of experimental fish was reduced with an increase in dietary SBM levels and in feeding period. Hepatosomatic index was significantly lower from fish fed the diets containing above $46\%$ of SBM than that from fish fed the control diet throughout the 160 days of experimental period, and fish fed diet containing above $46\%$ of SBM appeared to make restricted utilization of carbohydrate sources. These results may suggest that soybean meal could be used up to $22\%$ in trout diet as a substitute for fish meal without unfavourable side effects.

• 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.