• Journal of Aquaculture
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• v.9 no.4
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• pp.311-320
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• 1996

In order to compare the growth and survival rates of grey mullet (Mugil cephalus) juveniles in different salinities, the fish reared in seawater (SW) abruptly were transferred to each experimental rearing water of $0\%SW\;(0\%_{\circ}),\;25\%SW\;(7.7\%_{\circ}),\;50\%SW\;(16.1\%_{\circ})$ and $100\%SW (32.8\%_{\circ})$. Growth rates in total length and body weight of fish in $25\%$ SW, $50\%$ SW and $75\%$ SW were greater than that in $0\%$ SW (P<0,05). Decreased salinity appeared to have an acute, but appetite depressive effect in short term in the experimental groups. Survival rate was low in $0\%$ SW (P<0.05), although those were more than $81\%$ in all salinities. There were no differences in thickness of epidermis and dermis layers in fish skin among the all experimental groups at the end of experiment. But the thickness of lipid layer in $0\%$ SW fish showed the significant differences to those in $50\%$ SW and $100\%$ SW (P<0.05). With decreased salinities, oxygen consumption was found to be decresed in the other experimental groups compared to the group in $100\%$ SW. The levels of lethal dissolved oxygen in $0\%$ SW to $100\%$ SW were 1.18, 0.30, 0,28 and 0.31 ppm, respectively.

• Journal of Aquaculture
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• v.9 no.4
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• pp.353-361
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• 1996

The objective of this study was to investigate the essential fatty acids requirement and its optimal level in dietary for young of tiger puffer. The young puffer fish used in feeding trial were average body weight 3.45g. Fish were randomly divided into 11 groups containing 30 fish each in 200 ${\ell}$ tank and reared for 8 weeks at ambient temperature. In basal diets, defatted squid meal, casein-Na and activated gluten were used as the dietary protein source, dextrin and ${\alpha}$-starch (gelatinized starch) as the digestible carbohydrate source and beef tallow as the lipid source. Five fatty acids added to diet were linoleic acid (LNA), linolenic acid (LNA), eicosapentaenoic acid (EPA) ,docos-ahexaenoic acid (DHA) and n-3 HUFA. Among that, the supplement of LA and LNA were $1\%$ of total composition of diet, respectively, and EPA, DHA and n-3 HUFA ranged from $0.3\~1\%$ level. Growth and feed efficiency were measured to the interval of 2 weeks, and analyzed fatty acids composition of diet and liver by GCL. As a result of 8 weeks experiment, predominant growth were shown in $0.5\~1\%$ n-3 HUFA and $0.5\%$ DHA than others (P<0.05). In comparison of efficiency among EPA, DHA and n-3 HUFA groups, the most results were revealed in n-3 HUFA and the least in EPA. The adding effect was shown in EPA by increasing the fatty acids content from 0.5 to $1\%$ in diet. However, sudden decline and steady state in growth were observed in $1\%$ DHA and $1\%$ n-3 HUFA, respectively. The feeding efficiency and protein efficiency ratio were high in n-3 HUFA groups and $0.5\%$ DHA. Consequently, it is assumed that young puffer requires n-3 HUEA both EPA and DHA as essential fatty acids. The optimal content in diets are about $0.5\%$ of HUFA or DHA.

• Journal of Aquaculture
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• v.9 no.4
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• pp.363-375
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• 1996

The effects of the yeast, Phaffia rhodozyme in the diet on growth, body composition, muscle elasticity and pigmentation of Israeli strain of common carp, colored carp and Nile tilapia were investigated. Ten percent of the yeast was added to semi purified diet as an experimental feed 1. Ten percent of brewers yeast in the semi purified diet (experimental feed 2) was tested for comparing the growth performance between two semi purified diets. A commercial diet was also used for the check of growth rate of the semi purified diets. All experimental fish were fed for 10 weeks. The weight gains among the experimental fish were not significantly different (P>0.05). There were not significantly different in body composition, muscle elasticity among the the fishes fed three experimental diets. There were significant differences (P<0.05) of pigment deposition in the muscle of Israeli strain of common can and on the skin of colored carp between treated and non treated group. But there were no differences of pigment deposition in flesh and skin of tilapia among the three diets.

• Journal of Aquaculture
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• v.11 no.1
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• pp.119-124
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• 1998

The relative effectiveness of C21-steroids and human chorionic gonadotropin(HCG) on maturation and ovulatin was investigated in vitro using the isolated oocytes or ovarian fragments from the sea bass, Lateolabrax japonicus. ${\alpha}$-hydroxy, 20${\beta}$-dihydroprogesterone(17${\alpha}$20${\beta}$OHP : 5, 50, 500, 1000ng/ml), 17${\alpha}$-hydroxy, 20${\alpha}$-dihydroprogesterone(17${\alpha}$20${\alpha}$OHP : 5, 50, 500, 1000ng/ml) and HCG (5, 50, 500IU/ml) were effective in inducing oocyte maturation, GVM (germinal vesicle migration) or GVBD(germinal vesicle breakdown), compared to control except 17${\alpha}$20${\beta}$OHP and 17${\alpha}$20${\alpha}$OHP at 5ng/ml. 17${\alpha}$20${\beta}$OHP showed the greatest effect on oocyte maturation at 50ng/ml. A combination of 17${\alpha}$20${\beta}$OHP(50ng/ml) and HCG(500IU/ml) led to a significant increase (p<0.05) in GVBD when compared with 17${\alpha}$20${\beta}$OHP or HCG alone. These findings suggest that the two in combination acts synergistically to induce GVBD. 17${\alpha}$20${\beta}$OHP (1~1000ng/ml) and HCG(1~500IU/ml) also induced ovulation in ovarian fragments at all concentrations used ; more effective at lower concentrations(1~50ng/ml or IU/ml). It was shown that HCG was more potent in inducting ovulatin than 17${\alpha}$20${\beta}$OHP.

• Journal of Aquaculture
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• v.13 no.4
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• pp.285-293
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• 2000

Mortality suffered by the sea squirt in indoor experiment was higher at the stocking density of 12 kg than that at 3 and 6 kg. Daily mortality was also higher at 8 t:: thermal fluctuation than that at 3 and 5$^{\circ}C$. The thermal fluctuation observed at the depth of 5 m during June was higher, i.e. 7.4$^{\circ}C$ but it was just 2-4$^{\circ}C$ during mid-May. It did not fluctuate at all during the period from January to February. Mortality was higher at the stocking density of 12 kg during June than at 10 and 15 m depth.

• Journal of Aquaculture
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• v.13 no.4
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• pp.325-330
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• 2000

For development of all male seed production at hatchery scale, a comparative study was made on the seed production traits of supermale (IT - t) and superfemale (IT - L1 ~) Nile tilapia, Oreochromis niloticus. Supermales were crossed with normal females (XX- f) and the superfemales with normal males (XY - t ) or sex reversed males (XX- L1 t); progeny survival of these crossings and sex ratio were evaluated. Hatching success of the eggs, fertilized by the supermale was significantly lower than that by the normal male. Over 95-99 % progenies sired by crossing supermales with normal females were males, while 52-55 % progenies alone were males with the cross of normal males and normal females. Hatching success and survival of alevins were significantly higher for the progenies of the crosses between superfemales and sex reversed males than those resulting from the crosses between superfemales and normal males. However, there was no significant difference in the sex ratio among the progenies of these crosses. Therefore, crossings of superfemales with sex reversed males provide the highest percentage of survival and male progenies.

• Journal of Aquaculture
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• v.17 no.3
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• pp.221-227
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• 2004

In the present study, we investigated the effects of food and salinity on growth and survival of river puffer, Takifugu obscurus offsprings in indoor land-based tank during the early development. In the food experiment, the river puffer larvae (TL 8.7$\pm$0.1 mm, BW 20.0$\pm$3.2 mg) were fed with tubificid, Limnodrilus gotoi, water flea, Daphnia carinata, mysid, Neomysis awatschensis, Manila clam, Ruditapes philippinarum and artificial food together Artemia nauplii for 30 days, and the growth and the survival of larvae were investigated. In the salinity experiment, the river puffer larvae and juvenile at three stages (Stage I: TL 5.8$\pm$0.4 mm; Stage II: TL 12.0$\pm$0.2 mm, Stage III： TL 44.5$\pm$0.7 mm) were supplied with Artemia nauplii, water flea and/or artificial food and were reared in 0, 10, 20 and 30 psu at respective stages. The results shows that the growth rates of larvae feeding with artificial food and tubificid together Artemia nauplii were higher than those of larvae in other groups, but the survival rates of larvae feeding with water flea and mysid together Artemia nauplii were higher than those of larvae in other groups. In salinity, the results shows that the growth and survival rates of offsprings were significantly higher in 10∼20 psu than those in 0 and 30 psu at Stage I and n. At Stage III, the growth and the survival rates were the highest in 20 psu, but the lowest in 0 psu. However, it should be noted that the rates in 0 and 30 psu were significantly enhanced at Stage III in comparison with those at Stage I and II. Therefore, it is concluded that river puffer, T. obscurus is euryhaline marine species, which can normally grow and live at salinities from 0 to 30 psu, and that a combinative supplement with Artemia nauplii and water flea, D. carinata may confer an advantage on growth and survival of the river puffer offsprings in indoor land-based tank.

• Journal of Aquaculture
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• v.17 no.2
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• pp.109-114
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• 2004

The effects of different concentrations (0, 0.3, 0.6 and 0.9%) of fish feed additives (Hanbangchun and Olyukchun) utilizing effective microorganisms and herb medicine on activity of liver function were examined in olive flounder, Paralichthys olivaceus, Moreover, we investigated the characteristics of the additives. Total number of microorganisms (Lactic acid bacteria, Bacillus subtilis, Saccharomyces cerevisiae, Photosynthetic bacteria and Azotobactor) in the additives was 5.6${\times}$10$^{8}$ CFU/g in the Hanbangchun and 3.0${\times}$10$^{8}$ CFU/g in the Olyukchun. Levels of three typical pathological microorgamisms (Edwardsiella tarda, Vibrio anguillarum and Streptococcus sp.) in moist pellets (MP) were significantly decreased by the additives in a concentration-dependent way. Hepatosomatic index of fish in the 0.3% group was significantly increased. Total serum protein was increased in all the groups containing additives, but the protein content in liver was higher in the control group. Higher activities of catalase and superoxide dismutase which are involved in physiological defense mechanisms were found in the dietary groups containing 0.3% and 0.6%, respectively. These results suggest that the additives, Hanbangchun and Olyukchun, can increase tolerance of olive flounder against stress and hypoxic conditions by increasing activities of body antioxidant enzymes.

• Journal of Aquaculture
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• v.17 no.2
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• pp.97-102
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• 2004

We examined the effects of stimulants including sunlight and UV-irradiation on the spawning induction and early development of the noble scallop, Chlamys nobilis. The sunlight stimulation resulted in nuch faster spawning induction (100% success within 40 minutes) compared to UV-irradiation (100% success within 70 minutes). Early development of the scallop larva took place between 15$^{\circ}C$ to 3$0^{\circ}C$. The time to reach the early D-shaped stage was 63.5, 31.5, 18.5 and 17.0 hours at 15, 20, 25 and 3$0^{\circ}C$, respectively. The correlations between the water temperature-(WT) regimes and the time (t) required for each developmental stage are as follows. 2 cell stage: 1/t=0.0606WT-0.6194 ($r^2$=0.9791) 8 cell stage: 1/t=0.0304WT-0.3453 ($r^2$=0.9941) Morula: 1/t=0.0100WT-0.1049 ($r^2$=0.9663) Trochophore: 1/t=0.0058WT-0.0618 ($r^2$=0.9848) D-shaped larva: 1/t=0.0030WT-0.0282 ($r^2$=0.9731) These correlations indicated that the biological minimum temperature of the species is around 10.44$^{\circ}C$. The highest survival rate up to D-shaped larva at different water temperature was observed at $25^{\circ}C$.

• Journal of Aquaculture
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• v.17 no.3
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• pp.167-172
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• 2004

Chemoenzymatic method was used in this study to evaluate the quality of cultured red seabrim. Level of ATP related compounds, ATPase and Adenylate energy charge (AEC) well reflected changes in condition of fish. ATP level in the muscle of exercised cultured red seabream was decreased significantly during cultured period. In contrast, the level of ADP in the muscle was increased during the period. Level of ATP related compounds in the muscle of cultured red seabream without exercise didn't show significant difference compared to the exercised group. AEC value in muscle of cultured red seabream without exercise was 0.89$\pm$0.02, while AEC value of the exercised group was 0.88$\pm$0.04. ATP and AEC levels among different size of fish did not show any significant difference. AEC value in all sample was higher than 0.8, indicating that the condition of cultured fish was healthy. Activity of Mg2$^{＋}$ (＋Ca2$^{＋}$), Mg2$^{＋}$ (-Ca2$^{＋}$) and Ca2$^{＋}$-ATPase during culture period did not change significantly, regardless of exercise. Therefore, the AEC appears to have some validity as fish health indicator.