• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.233-238
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• 1981

A recirculating water system without filter bed was used for a high density experimental rearing of common carp, Cyprinus carpio, during the summer of 1981. Of the water system, 3 tanks were used for stocking each tank with 10,000, 20,000 and 30,000 common carp fingerlings which averaged 0.6 g. The water in the system was maintained in dark green colour by heavy growth of phytoplankton during the most period of the experiment. In this experiment, the best daily growth rate, $3.7\%$, was obtained from the 10,000 fish group followed by $2.8\%\;and\;3.0\%$ from the 20,000 and 30,000 fish groups respectively. Thus there was no significant difference between the latter two groups. Especially, notably high concentration of total ammonia, $5\sim7$ ppm ammonia-N, in the culture water appeared during the most experimental period, but this did not seem to have affected feeding and growth of the fish when the water was kept at heavy bloom. It was also obvious that the outbreak of columnaris disease was effectively depressed in this green water recirculating system compared to that in clarified recirculating system. One tank ($7m^2$) of this system was stocked with 446 common carp of intermediate size averaging 352.2 g and after 40 day rearing they grew to 486.3 g in average with a daily growth rate of $0.8\%$. This result was a little inferior to that reared in a tank of the clarified water system as control which showed $1.0\%$ daily growth rate. Therefore, before an initiation of the commercial production of fish in this method, further studies concerning the amount of ammonium with its effect on the fish under rearing in this system and the columnaris disease problem should be carried out.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.380-387
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• 2023

Stocking density is associated with Paralichthys olivaceus growth; thus, fish should be rapidly reared at high densities for commercial reasons. Studies have reported that high stocking density retards growth; however, few have investigated the malformations caused by stocking density stress. This study compared the growth and malformation rates of P. olivaceus at different densities and stress- and immune-related gene expression between malformed and normal fish. Forty days post-hatching, fish (total length, 1.49±0.02 cm) were reared at 800 (low density; LD), 1500 (medium density; MD), and 4000 (high density; HD) fish/m², and the growth rate was measured weekly. On day 30, RNA was extracted from the kidneys, and the expression of stress-, immune-, and malformation-related genes was analyzed using qRT-PCR. The malformation rate in the HD groups was approximately three times higher (62%) than that in the LD and MD groups (approximately 20%), and growth was lower regarding length and weight. The stress-related (HSP70 and GPX) and immune-related (PIR and IgM) genes showed higher mRNA expression in the HD group and malformed fish than in the LD group and normal fish. However, TLR3 showed the opposite results. In summary, high stocking density suppressed growth and increased malformation risk in P. olivaceus.

• Fisheries and Aquatic Sciences
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• v.5 no.3
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• pp.229-234
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• 2002

Possibility of raising sunshine bass during the winter season in Korea was investigated. Also, the effect of feed on growth and body composition of sunshine bass was compared at the various salinity. Twenty sunshine bass $(Mean\;weight\;\pm S.D.\: :\;53.9 \pm 0.24 g)$ were stocked into the eighteen circular flow-through tanks. A 2 (feed) $\times$ 3 (salinity) factorial design with triplicate was used for this study. Feed was prepared into the 2 groups: the raw fish-based me>ist pellet (MP) containing $59.5\%$ crude protein and $9.4\%$ crude lipid, and commercial sinking red sea bream feed (CF) containing $49.9\%$ crude protein and $9.4\%$ crude lipid, respectively. And salinity was prepared into the 3 groups: freshwater $(0\%)$, brackishwater $(15\%)$, and seawater $(32\%)$. Fish were fed to satiation twice daily for 6 days a week. Fish were all survived at the end of the 8-week feeding trial. Weight gain (WG) and specific growth rate (SGR) of sunshine bass were significantly (P<0.05) affected by both feed and salinity. WG and SGR of sunshine bass fed the MP were significantly (P<0.05) higher than those of fish fed the CF in the same salinity. Amount of dry feed fed was significantly (P<0.05) affected by both feed and salinity. Feed consumption by sunshine bass fed on the MP was significantly (P<0,05) higher than by fish fed on the CF in the same salinity. Feed efficiency ratio (FER) was significantly (P<0,05) affected by salinity, but not by feed. Protein efficiency ratio (PER) was significantly (P<0.05) affected by both feed and salinity. Moisture and protein content of the whole-body of fish was not significantly (P>0.05) affected by either feed or salinity. However, lipid and ash content of the whole-body of fish was significantly (P<0.05) affected by salinity, but not by feed. In conclusion, the MP was superior to CF for growth of sunshine bass during the winter season in Korea and no mortality occurred. And sunshine bass seemed to grow better in freshwater $(0\%)$ and brac-kishwater $(15\%)$ than seawater $(32\%)$ under these experimental conditions, in terms of improvement in FER and PER in freshwater or brackishwater.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.643-650
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• 1996

A long term feeding trial was conducted to study the effects of different dietary vitamin C levels on growth and its tissue distributions in juvenile Korean rockfish, Sebastes schlegeli. Prior to the start of feeding trial, fish were fed the basal diet supplementing no L-ascorbic acid for four weeks to minimize their body reserves of vitamin C. Then fish were divided into six groups with triplicates and given one of the laboratory semipurified diets supplementing either 0, 25, 50, 75, 150, or 1500 mg L-ascovbic acid (AA)/kg diet $(C_0,\;C_{25},\;C_{50},\;C_{75},\;C_{150},\;&\;C_{1500})$. Fish fed the $C_0$ diet had lower percent weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio than did fish fed the other diets (P<0.05). After 28 weeks of feeding trial, tissue AA concentrations of fish fed $C_0$ diet were lower than those of fish fed $C_{1500}$ diet (P<0.05). A large amount of total tissue Ah may be reserved in muscle, but the unit AA concentration seemed to be higher in brain than did the other tissues. The growth performances of fish fed $C_{25}$ diet were not different compared to those of fish fed $C_{50}-C_{1500}$ diets (P>0.05), and diet analysis of vitamin C showed that the $C_{25}$ diet had 65 mg AA/kg diet. Therefore, the present long-term study may suggest that the dietary vitamin C requirement is approximately 65 mg AA/kg diet in juvenile Korean rockfish.

• Fisheries and Aquatic Sciences
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• v.22 no.11
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• pp.25.1-25.9
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• 2019

Background: Due to the continuous demand for fish coupled with decline in capture fisheries, there is the need to increase aquaculture production to meet the demand. Aquaculture is faced with high cost of feeding since fish oil and fish meal are expensive. In view of this, there are calls to explore alternatives that are cheap and reliable. Objectives: This study on Oreochromis niloticus was conducted to evaluate the effects of replacing fish oil (FO) with palm oil (PO) at 0%, 25%, 50%, 75%, and 100% on muscle fatty acid and proximate composition as well as growthrelated enzyme activities and mRNA expression. Methods: Oreochromis niloticus were fed five experimental diets (33% crude protein and 10% crude lipid) for 8 weeks. Feed had variation in fish oil and palm oil contents. After the 8 weeks feeding trial, five fish were sampled from each tank (15 from each treatment) and euthanized using an excess dose of tricaine methane sulfonate (MS-222 at 200 mg/L). Fatty acid and enzyme activities were analyzed using standard protocols. Also, RT-qPCR was used to quantify the expression levels of selected growth-related genes. Results: Fish fed 25% PO recorded the least muscle protein content and was significantly lower than the group fed 100% PO. Paired box protein 7 (Pax-7) enzyme activity was significantly higher in the group fed 50% PO compared to the groups fed 25% PO and 100% PO, while caplain-3 (Capn-3) was significantly lower in the group fed 0% PO compared to all other groups. There was a significant difference among treatments with respect to mRNA expression of Pax-7 and Capn-3. Group fed 25% PO had significantly lower mRNA expression of Pax-7, while the group fed 75% PO recorded significantly higher mRNA expression of Capn-3 compared to groups fed 0% PO, 25% PO, and 100% PO. Pearson's correlation analysis revealed that Igf-I and Igf-II mRNA expression have significant correlation with n-3 polyunsaturated fatty acids content in muscle. Conclusion: The results suggest muscle protein content could be modified if FO is replaced with PO. Also, mRNA expression of Pax-7 and Capn-3 is affected by replacing FO with PO.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.149-154
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• 2011

Two experiments were conducted to investigate the effects of dietary moisture content on the growth and gastrointestinal evacuation of sub-adult olive flounder (Paralichthys olivaceus) in the summer and winter seasons. In the first experiment, three experimental diets containing different moisture levels (7%, 15%) and additives were prepared by adding water and commercial additives (1% nutrients, 1% digestives) to commercial extruded pellets. Fish (initial weight: $332{\pm}9.2$ g) were distributed randomly into six 3000 L tanks (25 fish/tank) in a flow-through tank system. Two replicate groups of fish were fed the experimental diets to satiation for 14 weeks during the summer season ($21.4{\pm}2.5^{\circ}C$). Survival, weight gain, feed efficiency, and daily feed intake did not differ significantly among groups. In the second experiment, two experimental diets containing different moisture levels (8%, 23%) were prepared by adding water to commercial extruded pellets. Fish (initial weight: $646{\pm}6.7$ g) were randomly distributed into six 3000 L tanks (20 fish/tank) in a flow-through tank system. Three replicate groups of fish were fed the experimental diets to satiation for 19 weeks during the winter season ($12.2{\pm}1.2^{\circ}C$). Weight gain, feed efficiency, and daily feed intake did not differ significantly among groups. Gastrointestinal evacuation rates were determined after the end of the winter feeding trials. The stomach contents of fish fed diets containing different moisture levels peaked within 3 h after feeding and then decreased gradually over 40 h to approach pre-feeding levels. Intestinal contents began to accumulate 3 h after feeding and reached a maximum at 32 h, then declined until nearly complete evacuation around 56 h. The stomach contents reached moisture levels of approximately 70% within 3 h after feeding and then increased gradually. No considerable difference in moisture levels was observed in the stomach contents of fish fed diets with different moisture contents. The results of this study suggest that the gastric evacuation of sub-adult olive flounder was not affected by dietary moisture level and the addition of water to the diet had no beneficial effect on the growth of sub-adult olive flounder in the summer and winter seasons.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.1035-1040
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• 2003

This experiment was conducted to investigate the effects of fat sources on growth performance, nutrient digestibility, serum traits and intestinal morphology in weaning pigs. A total of 128 weaning pigs (Landrace${\times}$Large White${\times}$Duroc, $21{\pm}2$ days of age, $5.82{\pm}0.13kg$ of average initial body weight) were allotted in a randomized complete block (RCB) design with four treatments: 1) corn oil, 2) soybean oil, 3) tallow and 4) fish oil. Each treatment had 8 replicates with 4 pigs per pen. During phase I period (d 0 to 14), pigs fed corn oil or soybean oil diet tended to show higher ADG and FCR than any other treatments although there was no significant difference. During phase II period (d 15 to 28), pigs fed corn oil diet showed better ADG and ADFI than pigs fed soybean oil, tallow or fish oil. For overall period, growth performance of weaning pigs was improved (p<0.05) when pigs were fed soybean oil or corn oil. Apparent digestibility of energy and fat was improved when pigs were fed corn oil diet (p<0.05). Supplementation of corn oil resulted in higher serum triglyceride concentration than the other treatments (p<0.05). However, there was a lower cholesterol concentration when corn oil was provided compared to tallow or fish oil. Pigs fed corn oil tended to have increased villus height compared with soybean oil, tallow or fish oil treatment (p<0.05). This experiment suggested that vegetable oils such as corn oil or soybean oil, were much better fat source for improving growth performance of weaning pigs.

• Journal of Aquaculture
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• v.11 no.1
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• pp.83-90
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• 1998

The effects of Obosan in the diet on growth, percent weight gain, specific growth rate, feed conversion ration and body composition of nile tilpia were investigated. First feeding fry average weighing 11.0 mg were fed the diets containing 0%, 0.25%, 0.5%, 1.0% and 2.0% Obosan for 7 weeks. Body weight, percent weight gain, specific growith rate of fish fed the diets containing 0.25%, 0.5% and 1.0% Obosan were significantly higher than control diet (P<0.05). Feed conversion ratio of fish fed the diets containing 0.25% and 0.5% Obosan showed best results compare to other experimental groups (P<0.05). Juvenile average weighing 281.0g and adult fish average weighing 563.0g were fed control and 0.3% Obosan supplemented diet for 30 days and 175 days, respectively. Body weight, percent weight gain and specific growth rate were significantly higher in the fish fed Obosan supplemented diet than control diet (P<0.05). Crude protein, crude lipid, crude ash and moisture of dorsal muscle and liver were not significantly different between two experimental groups.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.11
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• pp.1588-1594
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• 2012

An 8-wk experiment was conducted to evaluate the effect of replacing fish meal (FM) with soy protein isolate (SPI) on the growth, digestive enzyme activity and serum biochemical parameters of juvenile Amur sturgeon (Acipenser schrenckii). SPI was used to replace 0, 25, 50, 62.5, 75, 87.5, 100% of dietary FM and 100% replacement supplemented crystalline amino acid. Healthy sturgeon with an average initial weight of $26.38{\pm}0.24$ g were randomly assigned to 24 aquaria (8 treatments with triplicates each) at an initial stocking density of 11 fish per aquarium and cultured for 8 wks. The results showed that 75.00% or more substitution resulted in a poor weight gain rate, feed conversion ratio and survival rate compared to that of fish fed the control diet (p<0.05), whereas no significant differences were observed between diets of 25.00% to 62.50% substitution. Protease, lipase and amylase activity in foregut, mid-gut and hindgut were significantly (p<0.05) decreased by diets where SPI replacement levels were 62.50% or more. Levels of serum total protein (TP) and globulin decreased significantly from 21.03, 10.34 to 14.05, 5.63 g/L with the increasing dietary SPI (p<0.05), but alkaline phosphatase activity significantly increased (p<0.05). In addition, supplemental crystalline amino acid in the FM absence diet did not improve growth performance, intestine digestive enzyme activities and serum biochemical parameters. In conclusion, the results from this study showed adverse effects of inclusion of SPI in diets on growth performance, feed utilization and serum biochemical parameters in juvenile Amur sturgeon. Based on WGR and replacement ratio presented in this report, a 57.64% replacement level was recommended.

• Ocean and Polar Research
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• v.43 no.2
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• pp.89-98
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• 2021

The seagrass habitats are a highly productive marine ecosystem which provides nursery ground and shelter for many fish and invertebrate species. Pholis nebulosa (Temminck & Schlegel, 1845) is one of the most abundant seagrass fishes in the coastal waters of Korea. The estimation of fish production is key for devising conservation measures and ensuring fish resources sustainability. A total 894 P. nebulosa ranging from 3.83 to 26.5 cm total length (TL) were collected monthly in 2006 with a small beam trawl in a seagrass bed of southern Korea. Growth parameters of P. nebulosa were estimated using the von Bertalanffy growth model, and production was estimated using a general equation which relates daily fish production to ash-free dry weight (AFDW), biomass, and water temperature. The von Bertalanffy's growth equation was estimated as: L_t = 28.3823(1-e^{-0.7835(t+0.9864)}). The densities, biomass, daily, annual production, and P/B ratio were 0.069±0.061/m^-2, 1.022±0.621 g/m², 0.005±0.004 g AFDW/m²/day, 1.676 g AFDW/m²/yr, and 1.641, respectively. Monthly variation in production of P. nebulosa peaked during March and April 2006 (0.0139 and 0.0111 g AFDW/m²/day), whereas the lowest value of 0.0005 g AFDW/m²/day was in December. Monthly change in production of P. nebulosa was positively correlated with biomass and condition factor. Our results will contribute to the conservation of seagrass ecosystems, which are still undisturbed in the study area.