• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.29-31
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• 1981

The eels Anguilla japonica were reared in an indoor aquarium of $1m{\times}1m{\times}0.67m$ from June 7 to August 8, 1980. The eels used for the experiment were the smallest ones which were left over from 1974 to 1976 groups, of which the others grew out years earlier. The eels were fed pelletized feed, with the results of 1.05 to 1.678 in feed coefficient, and 0.96 to $1.46\%$ in daily growth rate. The results are well comparable to those of paste feed, which has been being used in the eel farming industry up to date and will be as well used in the future, if any innovative way will not be developed. If pelletized feed can be used without any other hazards, the cost of feed will be remarkably reduced by eliminating costly $\alpha-starch$ which is absolutely necessary for the paste feed preparation, and also by preventing scattering of feed materials which is always associated with paste-feed during feeding time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.199-206
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• 1982

Histological changes occurred by freezing storage and subsequent thawing, and changes of muscle fiber after heating and drying of the eel (Anguilla japonica) were observed under microscope . The results are as follows : (1) After one month of freezing storage the muscular tissue produced considerable number of extracellular and intracellular ice crystals. The sample stored at the temperature of $-40^{\circ}C$ produced ice crystals inside the muscle cells while sample stored at $-20^{\circ}C$, outside. (2) No changes were observed in the hypodermic fat after thawing regardless of storage temperature, while insufficient recovering of muscle cells were detected in the muscular tissue. Muscular tissues which have been stored $-20^{\circ}C$ showed severe change in shape due to dehydration. (3) Microscopic observation on muscle homogenate showed loss of transparency due to free-zing, disfiguration and contraction by drying and water seperation, and elasticity by heating.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.623-628
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• 2010

The distribution of fluoroquinolones was investigated in the carp (Cyprinus carpio) and eel (Anguilla japonica) after an oral dose of 20 mg/kg body weight/day for 35 days. Blood samples were collected at 5 and 10 hours and 1, 2, 3, 5, 7, 9, 13, 20, 30, and 35 days after treatment. The fluoroquinolone concentrations were determined high- performance liquid chromatography with an ultraviolet detector. The recovery rates of fluoroquinolones in the fish samples ranged from 91.4-96.6, 91.2-96.5, and 90.4-98.6% for concentrations of 0.1, 0.5, and $1.0\;{\mu}g/g$, respectively. In the blood of carp, ciprofloxacin, enrofloxacin, norfloxacin, and sarafloxacin reached maximums level of 11.03, 9.37, 9.10, and $9.81\;{\mu}g/g$ 10 hours, 1 day, 10 hours, and 10 hours after treatment, respectively. In the eel blood, these reached maximum levels of 12.65, 11.18, 11.91, and $8.74\;{\mu}g/g$ all at 10 hours. Carp sample concentrations of ciprofloxacin, enrofloxacin, norfloxacin, and sarafloxacin were not measurable 20, 30, 20, and 20 days after treatment, respectively, in all experiments (

• Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.85-92
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• 2013

To determine the relative importance of two main factors, diet or culture environment, that affect the proximate composition and main nutritive ingredients (vitamin A, vitamin E, cholesterol, fatty acid composition) in cultured eels, we analyzed the composition of eels fed diets of formula feed (FF) produced by four different companies and of eels cultured at five different eel farms that provided only one of the four different FFs. The four commercial eel FFs did not markedly differ in proximate composition or major nutritive compounds, and consequently, these variables did not significantly differ in cultured eels fed the different FFs. The FF imported from Japan was marginally superior to the two domestic commercial FFs and the FF imported from Taiwan in terms of the proximate composition and main nutritive ingredients of both the FF itself and the eels cultured on it. However, proximate composition and main nutritive ingredients significantly differed among eels cultured at the five farms that used a different FF and among eels fed the four different FFs at the same farm. In conclusion, the difference in quality between domestic and Japanese FFs in terms of eel culture was small, whereas physical or chemical environmental differences among farms during eel culture may more strongly affect the proximate composition and levels of the main nutritive ingredients in cultured eels.

• Korean Journal of Veterinary Research
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• v.50 no.1
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• pp.29-35
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• 2010

Yersinia (Y.) ruckeri has been recognized as a serious bacterial pathogen to several kinds of fish, including rainbow trout. However, there are no reports about the characteristics and pathogenicity of Y. ruckeri isolated from farm-cultured eels. In this study, we isolated and characterized Y. ruckeri from the farm-cultured eel Anguilla japonica in Korea. We investigated the phenotypic and genotypic characteristics of Y. ruckeri and tested the virulence of Y. ruckeri isolates on experimentally infected eels. Examination of the flagellar morphology of Y. ruckeri by electron microscopy showed peritrichous flagella in its cell body. Biochemical reaction studies showed overall identical profiles between the isolates and the reference strain of Y. ruckeri in API 20E and API ZYM tests. We sequenced the 16S rRNA of the Y. ruckeri (1,505 bp) for the genotypic characterization (National Center for Biotechnology Information accession number EU401667). Comparison of the 16S rRNA sequences with previously reported Y. ruckeri strains revealed similar phylogenetic relationships. In the virulence assay of the Y. ruckeri on eels, the eels exhibited listlessness, but Y. ruckeri was reisolated from those of the gills and kidneys.

• Horticultural Science & Technology
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• v.18 no.6
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• pp.827-833
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• 2000

This study was carried out to investigate the effect of plant growth retardants (daminozide, chlormequat, uniconazole, paclobutrazole) and fungicides of triazole chemical (hexaconazole, microbutanil, difenoconazole, terbuconazole, bitertanol) on the growh of 'New Guinea' impatiens. Plant height and canopy were decreased by all kinds of plant growth retardants tested in both 'Anguilla' and 'Papete'. Especially, uniconazole and paclobutrazole were most effective in inhibition of top growth. However, the content of chlorophyll increased at all treatments of plant growth retardants and stem diameter tended to be increased at the highest concentration of all kinds of plant growth retardants tested. The results in all cultivars tested, with the experiment of triazole fungicides, were similar to the results of experiment with plant growth retardants. These results suggest that fungicides of triazole chemical such as hexaconazole, microbutanil, difenoconazole, terbuconazole and bitertanol can be used for the promotion of quality in potted 'New Guinea' impatiens.

• Journal of fish pathology
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• v.21 no.3
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• pp.219-228
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• 2008

The effects of dietary yeast β-glucan administration on growth, nonspecific immune responses, serum lysozyme, skin mucous lysozyme, NBT (nitroblue tetrazolium) reduction by phagocytes, and disease resistance against Edwardsiella tarda in Japanese eel, Anguilla japonica were evaluated. Fish were fed the diets supplemented with 0%, 0.1% and 0.5% of yeast β-glucan to a commercial diet for 6 weeks. The body weight gain from the fish fed on the 0.5% supplemented diet for 6 weeks was significantly higher than the control. Both serum and skin mucous lysozyme were significantly higher in the all experimental groups except 2 weeks of 0.5% group. The bactericidal activity of serum was slightly increased at 6 weeks. Also, The intracellular superoxide anion production of kidney phagocytes was significantly higher in the all experimental groups. The diet supplemented with 0.1% were also found to raise the relative percent survival (RPS) of Japanese eel after an artificial challenge with 1×107 cells of Edwardsiella tarda per fish. The results suggested the potential of yeast β-glucan to activate some innate immune responses and to improve the growth in Japanese eel.

• Korean Journal of Environment and Ecology
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• v.31 no.1
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• pp.54-61
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• 2017

We investigate predation rates of larvae and juveniles of Rana catesbeiana by using six native predatory fishes and six birds to select effective species to ecological control and management of R. catesbeiana that is invasive alien species and affects seriously wetland in Korea. Among freshwater fishes, Pseudobagrus fulvidraco, Silurus asotus and Channa argus ate larvae and juveniles of R. catesbeiana, and prefer the former, however Opsariichthys uncirostris, Monopterus albus and Anguilla japonica didn't eat at all. Six experimental water birds, Cygnus columbianus, Cygnus cygnus, Anas crecca, Aix galericulata, Anas penelope and Anas formosa nerver ate them. We were able to confirm control of R. catesbeiana probability using the native predatory fishes in Korea wetland.

• Journal of fish pathology
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• v.21 no.2
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• pp.119-127
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• 2008

Oxytetracycline (OTC) has been widely used in eel culture as a therapeutic and prophylactic agent because of its broad-spectrum activity against gram-positive and -negative bacteria. The oral treatment dosage of OTC approved for the treatment of edwardsiellosis, furunculosis and vibriosis in eel is 50 mg/kg/day for 3-7 days in Korea. To determine new optimum dose of OTC in eel, the pharmacokinetics of OTC after single oral administration (100 mg/kg B.W., 200 mg/kg B.W.) in cultured eel, Anguilla japonica was examined. In oral dosage of 100 and 200 mg/kg body weight, the highest plasma concentrations of OTC were 1.19±0.42 ㎍/㎖ and 2.69±0.57 ㎍/㎖, respectively. Plasma concentrations of OTC were not detected after 720 h post-dose in all experiments. The kinetic profile of absorption, distribution and elimination of OTC in plasma wwas calculated fitting to a 1- and 2-compartment model by WinNonlin program. The following parameters were obtained for a single dosage of 100 and 200 mg/kg respectively: 1-compartment model, AUC= 82.48 and 432.68 ㎍*h/㎖, Tmax= 3.93 and 14.24 hr, Cmax= 0.94 and 2.34 ㎕/㎖; 2-compartment model, AUC= 448.73 and 530.65 ㎍*h/㎖, Tmax= 6.37 and 8.96 hr, Cmax= 0.90 and 3.21 ㎕/㎖.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.65-70
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• 2019

A total of 23 individuals of glass eel (Anguilla japonica) were investigated from two estuarine barrages of the Nakdong River in 2016. It was observed that most individuals migrated through the eastern barrage, compared to the western. Individual numbers differed significantly along the corridor modification of the barrages; for example, the number of individuals was two to three times higher after the modification. These results indicate that modification of fish way and lock gate for has facilitated migration of glass eel, and our study potentially offers the operation strategy of estuarine barrage in order to induce more active migration of glass eel.