• Animal Systematics, Evolution and Diversity
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• v.9 no.1
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• pp.51-59
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• 1993

A gobiid fish, Parioglossus dotui Tomiyama is described from 359 specimens collected at Cheju-do and Pusan, in August 1994 of 1986. This is the first definitive record of the species in the Korean waters. Parioglossus dotui having a small-sized body usually is found swimming in schools. The branchiostegals are 5 in number on each side. It grows up to 40mm in total length. Most of ventral fins are separated and connected with rudimentray membrane. In this species, the lateral line were indistincet or absent. The caudal fin slightly emarginates or truncates in both sexes, with a dark spot at the border of the base. It Inhabits inlet waters and estuaries of rivers. "Deungsul mang-dug" is proposed as Korean name of this species.

• Journal of Aquaculture
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• v.12 no.4
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• pp.303-307
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• 1999

Copepod is useful live food organism in the larval rearing. However of fin fish, culcures of copepod species (Specially calanoida and cyclopoida) were very difficult under artificial management conditions. In this study, we report successful culture of a free swimming cyclopodia copepod species (Apocyclops sp.) by easily baker's yeast as food. The maximum culture density of Apocyclops sp. was observed 11,200±2,660 ind/ℓ during the 30 days culture periods in the 1.5ℓ culture tanks. The nauplii were growth up maximum density 6,400±432 ind/ℓ on day 16th. The number of egg carring female was observed maximum density (666.7 ind./ℓ) of two times after 6days and 28 days of initial culture.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.2
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• pp.103-110
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• 2016

This study aims to estimate the species, size and shape of fish using a non-contact 3 dimensional pattern laser so that this preliminary test was carried out to understand the structural feature and length of goldfish according to water turbidity and depth in the aquacultural tank. 3-D pattern laser could clearly detect its morphological shape except the caudal fin due to soft tissue. Since the sensing strength of line laser light according to depth has sufficient power, it is possible to measure its depth and structural feature in the detected range. The result showed that the measured error of individual's fork length was less than ${\pm}1%$ in the water using 3-D pattern laser, when compared with the measured value in the air.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.4
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• pp.316-321
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• 2005

We designed and implemented fish robots for various purposes such as autonomous navigation, maneuverability control, posture balancing and improvement of quick turns in a tank of 120 X 120 X 180cm size. Typically, fish robots have 30-50 X 15-25 X 10-20cm dimensions; length, width and height, respectively. It is essential to have the ability of quick and smooth turning to avoid collision with obstacles or walls of the water pool at a close distance. Infrared distance sensors are used to detect obstacles, magneto-resistive sensors are used to read direction information, and a two-axis accelerometer is mounted to compensate output of direction sensors. Because of the swing action of its head due to the tail fin movement, the outputs of an infrared distance sensor contain a huge amount of noise around true distances. With the information from accelerometers and e-compass, much improved distance data can be obtained by fuzzy logic based estimation. Successful swimming and smooth turns without collision demonstrated the effectiveness of the distance estimation.

• Journal of fish pathology
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• v.18 no.1
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• pp.29-37
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• 2005

This study investigated external symptoms, behavior characteristics and the distribution pattern of the scuticociliates in the skin, gill and blood vessel of the tiger puffer, Takifugu rubripes, infected with scuticociliates among tiger puffer cultured. The fish infected with scuticociliates did not show any external symptoms, such as change in body color or swimming behavior, in the early infection stage. However, they showed congestion, erosion, and ulcer on the skin and fin at advanced stages. They showed a turning movement, mainly stayed on the bottom, and swam with their mouths open at the surface of water. Some fish showed a sudden swimming movement of zigzag type. The scuticociliates were ovoid in shape and $20\times40{\mu}m$ in size. The scuticociliates had a contractile vesicle and a caudal cilium that ranged 10-12 ${\mu}m$, and reproduced by binary fission. Therefore the scuticociliates were identified as ciliated, belonging to class Hymenostomatia, order Scuticociliatida in morphogenetic character. The gills infiltrated with scuticociliates showed clubbed gill filament due to hypertrophy of gill lamella. Within the blood vessels, scuticociliates were observed one to ten individuals, depending on diameter of the blood vessels. Some of the scuticociliates were observed to have ingested erythrocytes.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.589-600
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• 2015

The purpose of this study was to verify the analysis of differences between importance and satisfaction of destination attractiveness for the national marine sports games using IPA method. By doing so, this study aimed to utilize the result of study for a practical marketing strategy in operating and establishing Korean marine sports market circumstances. The participants of this study consisted of 328 who were participated in marine sport event (yacht, fin-swimming, canoe, triathlon and so on) of 9th national marine sports games. Samples were extracted by convenient sampling method. A total 328 questionnaires were collected in this study except data which did not respond or trustless responded. In data processing, Cronbach's ${\alpha}$, frequency analysis, paired t-test and Importance-Performance Analysis were performed through SPSS 20.0. The results were as follows. First, I quadrant included Programs Multiplicity, Pamphlet, Stand preparations, Food Cleanliness, Effective Progress, Guide Know-How, Food taste. Third, II quadrant included Pre-Publicity, Internet Information, Proper Food Price, Shade Facilities, Convenient Parking, Restroom Cleanliness, Number of Restroom, Safety Facilities. Fourth, III quadrant included Entertaining Program, Number of Guide, Local Culture, Game Progress, Directional Sign. Fifth, IV quadrant included Performance Program, Well-Matched Event, View Distance, Various Food.

• Toxicological Research
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• v.33 no.2
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• pp.119-124
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• 2017

Hexavalent chromium is a bio accumulative toxic metal in water and fish. It enters aquaculture ponds mainly through anthropogenic sources. Hexavalent chromium concentrations and its effects on the morphology and behavior of Clarias gariepinus were investigated from four aquaculture ponds for 12 weeks. Chromium was measured using diphenyl carbohdrazide method; alkalinity and hardness were measured using colometric method and analyzed with Bench Photometer. Temperature and pH were measured using pH/EC/TDS/Temp combined tester. Temporal and spatial replications of samples were done with triplicates morphological and behavioural effects of the metal on fish were observed visually. Chromium ranged from no detection to 0.05 mg/L, alkalinity 105 to 245 mg/L, hardness 80 to 165 mg/L, pH 6.35 to 8.03 and temperature 29.1 to $35.9^{\circ}C$. Trend in the chromium concentrations in the ponds is natural > earthen > concrete > collapsible. There was a significant difference (P < 0.05) in chromium, alkalinity, water hardness, pH and temperature among the four ponds. Significant positive correlation also existed between alkalinity, water hardness, pH, with chromium. Morphological and behavioural changes observed in the fish include irregular swimming, frequent coming to the surface, dark body colouration, mucous secretion on the body, erosion of gill epithelium, fin disintegration, abdominal distension and lethargy. High chromium concentration in natural pond was due to anthropogenic run-off of materials in to the pond. Acidic pH, low alkalinity, low water hardness also contributed to the high chromium concentration. Morphological and behavioural changes observed were attributed to the high concentrations, toxicity and bio accumulative effect of the metal. Toxicity of chromium to fish in aquaculture could threaten food security. Watershed best management practices and remediation could be adopted to reduce the effects of toxicity of chromium on pond water quality, fish flesh quality and fish welfare.

• Development and Reproduction
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• v.21 no.4
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• pp.399-406
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• 2017

This study was conducted to investigate egg development and larvae morphological development of catfish and to provide basic data to clarify the genetic relationship with Siluriformes fish. The mother fish that was used in this study was caught in the stream of Nakdong River in Uiseong-gun, Gyeongbuk. The temperature range of the breeding was $23.0-25.0^{\circ}C$ (mean $24.0{\pm}1.0^{\circ}C$) and egg size was 1.62-1.70 mm (mean $1.66{\pm}0.05$, n=30). Eggs of catfish began hatching at 54 hours and 40 minutes after fertilization. Immediately after hatching, the total length of larvae was 3.60-3.65 mm (mean $3.62{\pm}0.03$, n=5) and had an egg yolk without swimming ability. On the third day after hatching, the larvae at the medium stage was 8.00-8.65 mm (mean $8.32{\pm}0.45$) in total length, and two pairs of whiskers formed around the mouth were elongated. On the 12th day after hatching, the larvae at the juvenile stage was 16.5-17.0 mm (mean $16.7{\pm}0.35$) in total length, and the stem of each fin was in the range, and the juvenile at this period was morphologically similar to the mother fish.

• Journal of fish pathology
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• v.17 no.1
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• pp.21-28
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• 2004

In late summer of 2001, a new disease "overturn disease" occurred among mud loach (Misgurnus mizolepis) cultured in a farm Chonbuk Province. The fish exhibited a lethargic, erratic and spiral swimming at the water surface. Affected fish showed swollen abdomen with accumulation of air bubbles in the intestinal canal. The bubbles were much larger in the anterior part than in the posterior part. Hematological and histopathological examinations were done. No significant differences were found in RBC count, Ht value and Hb concentration between the diseased and the healthy fish. Gill filaments showed proximal hyperplasia of the respiratory epithelia and fusing of the gill lamella. Hemorrhage and necrosis occurred in the intestinal epithelia and within the lamina propria, and the mucosal epithelia were separated from the muscularis. Hepatocytes underwent atrophy. In the fish experimentally tied between the annal fin and the anus by a thread to confirm accumulation of air bubbles within intestine, accumulation of air bubbles was confirmed. This disease in mud loach appeared to be induced by circulatory disturbances in the intestinal wall owing to accumulation of air bubbles in the alimentary canal after fed high protein diet throughout all culturing period.

• Korean Journal of Ichthyology
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• v.33 no.1
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• pp.15-21
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• 2021

The Nakdong nose loach, Koreocobitis naktongensis is an endangered freshwater fish endemic to Korea. The spawning behaviour of the K. naktongensis was observed after treating Ovaprim in laboratory aquarium from 20~27 April 2010. The behavioral patterns were categorized into three stages of pre-spawning, spawning and post-spawning behaviors. Before spawning K. naktongensis usually repeated taking a rest and swimming. On average, initial spawning activity started 11 to 12 hours later after injection with Ovaprim. During the spawning period, the number of spawning acts ranged from 1 to 18. The spawning ratio of female to male was 1 : 1. The male embraced the back of the female's dorsal fin with his lamina circularis. It looked like a complete circle at that time. After spawning, parental care was not observed. Individuals not participating in spawning have been observed to feed on some of the fertilized eggs.