• Journal of Marine Life Science
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• v.5 no.2
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• pp.51-57
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• 2020

Disinfection and maintenance of rearing water in aquaculture is an essential element for the prevention of fish diseases. This is especially important in recirculating aquaculture systems (RAS) in which fish are reared at high density using recycled water. In this study, tilapia was reared in two different RAS (one with plasma generator - PW system, another without plasma generator - No PW system). In plasma treated group, UVT% of water was improved clearly, and the number of heterotrophic bacteria decreased significantly after 40 days. Total weight gain of tilapia in PW system was significantly higher, and other growth indicators were also relatively higher although not statistically significant. In addition, the fish in PW system had a 100% survival rate, and there were no histological differences between fish from both systems. Fish did not seem to be affected by the toxicity of ROS. In conclusion, it is expected that plasma water can effectively deactivate fish pathogens and improve the quality of rearing water.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.05a
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• pp.103-106
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• 1998

식생활패턴의 변화로 수산물에 대한 이용이 급증하여 내수면을 이용한 양식도 활발히 이루어지고 있으나 상수원오염우려가 있어 이의 입지도 어려운 실정이다. 특히 틸라피아의 경우 틸라피아 성장에 필요한 여름철 고수온기가 짧아서 노지양식이 불리하기 때문에 온실 등의 가온시설을 이용해야 하므로 저온기에 난방비를 최대한 절감하기 위한 가온시설내에서 고밀도 순환여과식으로 사육되고있다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.244-245
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• 2003

한국의 내수면 어류양식은 송어, 틸라피아 및 잉어류가 주류를 이루고 있으나 과잉생산으로 인해 경제성이 낮으며, 최근 수입개방과 환경오염으로 담수양식 산업이 어려움에 처해 있는 실정이다. 따라서 새로운 고가의 양식어종 개발은 내수면 어류양식에 있어 시급히 해결해야 할 중요한 과제이다. 이러한 문제를 해결하기 위하여 최근에 광염성 해산어류의 뛰어난 삼투압 조절능력을 응용한 감성돔의 담수순화 양식이 시도되고 있다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.304-305
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• 2000

양어사료에서 단백질원의 비용은 다른 구성성분의 비용보다 많은 부분을 차지하고 있으며, 이제까지 단백질원으로는 주로 어분을 사용하여 왔으나 어분의 수요는 계속적으로 증가하는 반면 어분 생산량은 그에 못미쳐(Rumsey, 1994) 어분을 대체할 수 있는 단백질원을 발굴해 내는 것은 중요한 과제이다(Lee and Bai, 1997a, b). (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.369-373
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• 1985

The characteristics of a pathogen isolated from infected tilapia, which showed the external symptoms of fin erosion and body deceleration, were examined. The strain of isolated pathogen was identified as Flexibactor columnaris, The normal tilapia dipped into suspensions of the isolated pathogens has developed the infective symptoms. The strain of Flexibactor columnaris was sensitive to kanamycin, tetracycline, and amikacine, but resistant against sulfa drugs. This strain could not grow in the cytophaga media containing over $2\%$ NaCl or over $50\%$ sea water. In cytophaga broth containing more than $50\%$ or sea water instead of distilled water, the number of Flexibacter columnaris decreased from about $10^6/ml\;to\;10^4ml$ within one hour after inoculation. On the other hand, in cytorhaga broth containing more than $5\%$ of NaCl, the number rapidely reached less than 10/ml from about $10^5/ml$ within one hour after inoculation.

• Journal of fish pathology
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• v.27 no.2
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• pp.115-125
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• 2014

The effects of waterborne arsenic (As) exposure on antioxidant defense were studied in liver and gills of tilapia, Oreochromis niloticus under thermal stress. Tilapia were exposed to different As concentrations (0, 200 and $400{\mu}g/L$) at three water-temperatures (WT; 20, 25 and $30^{\circ}C$) for 10 days. In antioxidant response, glutathione (GSH) levels, glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione S-treansferase (GST) activities were significantly decreased depend on WT in the gills after As exposure. Also, the range of fluctuation in these enzymes activities was most significantly increased at $30^{\circ}C$ in the liver of tilapia exposed to As. The present findings suggest that a simultaneous stress by temperature change and As exposure could accelerate the alteration in antioxidant enzymes activities of tilapia.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.317-327
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• 1987

As a series of studies on the suitability as a second intermediate host of Clonorchis sinensis, artificial infection experiments were applied to Tilapia mossambica. And then, in order to elucidate the defence mechanism of the fish to Clonorchis, clonorchicidal substance in the epidermal mucus of the fish was isolated by silica gel column and thin layer chromatography and analyzed for its chemical structure by UV, IR and NMR-spectroscopy. The results obtained are summarized as follows: 1. The cercariae which attempted to contact with the fish in the water were observed under stereomicroscope. After contact, the cercariae began to separate their tail from the body after several minutes and then the number increased to $80\%$ more than 10 minutes after the encounter. But very few cercariae could actually invade the epidermis of the fish. 2. The fish were reared with Parafossarulus manchouricus which were shedding numerous cercariae of Clonorchis in the aquarium for 24 hours. Only a few cercariae could invade the epidermis but most of the invaded cercariae died out before forming their cysts. Very few number of the remaining encysted cercariae were also found to be in a state of suspended animation within 42 hours. 3. In the cases of the control fish, Pseudorasbora parva, numerous cercariae of Clonorchis were found to invade the fish through the epidermis under stereomicroscope. Then many metacercariae of Clonorchis were also found in the fish while they were kept in the aquarium. 4. A sample of the epidermal mucus of Tilapia mossambica was extracted with ethly ether 6 times repeatedly. In silica gel column chromatography, using petroleum ether: chloroform/30:70(v/v) as a first solvent and MeOH as a second solvent, the extract was fractionated into the yellow and brownish red solutions in the first solvent and the clonorchicidal brownish yellow solution in the second sovent. 5. The clonorchicidal brownish yellow solution was added to petroleum ether, and the mixture was stored for 5 days at $5^{\circ}C$ and was, then, separated into supernatant fraction and precipitate. Ten mg/ml of the supernatant fraction killed, in vitro, the excysted metacercariae in 45 minutes but the precipitate in 600 minutes. 6. In silica gel column chromatography, using acetone: benzene/10:90(v/v) as a solvent, the more clonorchicidal supernatant fraction was fractionated into the first fraction with Rf. 0.2966 and the second fraction with Rf. 0.072. In vitro, 10mg/ml of the first fraction killed the excysted metacercariae in 28 minutes, the second fraction in 80 minutes and the first fraction was, therefore, determined to be a final clonorchicidal substance. 7. By this purification procedures, the most clonorchicidal substance from the epidermal mucus of Tilapia mossambica was purified 71-folds with $0.2075\%$ yield. Infra red, nuclear magnetic resonance and ultraviolet spectrometric analysis of the purified substance revealed that the substance is linoleic acid. According to the results of the present studies it seemed that this species can not serve as a proper intermediate host of Clonorchis sinensis, and that defence mechanism to the fluke seems to be correlated with linoleic acid in the epidermal mucus of this species.

• Journal of Aquaculture
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• v.15 no.2
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• pp.119-121
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• 2002

A study on the acute toxicity in the Nile tilapia, Oreochromis niloticus fry showed that the 24hr-$LC_{50}$ was 18.6% for NaCl,152 ppm for formaline and 2.1 ppm for $KMnO_4$. The fry responded to narrow range of concentration of all the tested chemicals and their toxic effects were dose-dependent.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.339-344
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• 1990

The composition of muscle lipids and their fatty acid composition of two groups of tilapia, cultured in fresh and seawaters, were investigated. The total lipid(TL) of seawater culture group is a little richer than that of freshwater culture. The neutral lipid(NL) is the most abundant in muscle lipids of two groups, followed by the phospholipid(PL) and glycolipid (GL). The increment of TL content seemed to depend upon triglyceride(TG) fraction, because large portions of lipids are consisted of TG. Phosphatidyl choline(PC), phosphatidyl ethanolamine and sphingomyelin were identified in PL, and the content of PC was the highest. The principal fatty acids of muscle lipids were 14 : 0, 16 : 0 and 18 : 0 as for saturated fatty acids, and 16 : 1, 18 : 1, 18 : 2 and 22 : 6 as for unsaturated fatty acids. In particular, high contents of 16 : 0 and 18 : 1 were observed in TL, NL and GL. However, low contents of 18 : 1 and 18 : 2 were observed in PL, while they were high in polyunsaturated fatty acids with 20 : 4, 20 : 5 and 22 : 6. In the meantime, no significant difference was observed in the composition of muscle lipids and their fatty acids between two groups cultured in seawater and freshwater.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.237-238
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• 2000

최근 산업사회의 발전에 따라 수계 오염문제가 심각하게 대두되고 있다. 따라서 이들 오염물질에 대한 모니터링을 위한 방법들이 강구되고 있으며, 이 중에서 어류 간의 cytochrome P450 호소계는 지방친화성 물질의 오염상태를 평가할 수 있는 물질로 알려지고 있다(Payne et al., 1987). PCBs(Polychlorinated biphenyls)와 HCB(Hexachlorobenzene)는 유기염소계 화합물로서 환경중에 널리 분포하고 있으며, 이중 PCBs는 신경계, 면역계 및 내분비계 등 생체내에 미치는 영향이 크므로 내분비장애물질(endocrine disruptor)로 분류되고 있고, HCB는 독성이 강한 화합물로서 주로 농업에서 fungicide로서 사용되어 왔으며. 다양한 산업 연소과정의 부산물로 발생되고 있다. (중략)