• Journal of fish pathology
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• v.9 no.1
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• pp.15-19
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• 1996

The mature spores of present Myxobolus sp. was ovoid in front view with no distinct redges of folds, lemon-shaped in side view with a straight sutural ridge. Spore valves showed symmetrical and smooth. Spores were 9 to $12{\mu}m$ (Mean=$10.4{\pm}0.7$, n=50)in length, 6 to $9{\mu}m$ (Mean=$7.7{\pm}0.6$, n=50) in width and 5.0 to $7.5{\mu}m$ (Mean=6.2, n=7) in thickness. Two polar capsules of spore were pyriform in shape, equal or mearly equal in size, 3 to $6{\mu}m$(Mean=$4.6{\pm}0.6$, n=50) in length, 2 to $3{\mu}m$(Mean=$2.2{\pm}0.3$, n=50) in width, Polar filaments of spore were composed with six to seven coils within capsules. Extended polar filaments were 55 to $135{\mu}m$ (Mean=78.7, n=50)in length. The shape and measurements of the present Mysobolus sp. spores were very similar with the spore of M. cyprinicola Reuss, 1906.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.276-283
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• 2011

The growth and tolerance for water temperature and salinity were compared among red sea bream Pagrus major (RSB) black sea bream Acanthopagrus schregeli (BSB) and their hybrid ($F_1$), female RSB ${\times}$ male BSB. The growth of the $F_1$ fish did not differ until 27 days after hatching (dAH), after which the most rapid growth was observed until approximately 300 dAH, followed by RSB and BSB. However, the RSB had out grown the $F_1$ fish by approximately 303 dAH. By 480 dAH, the RSB were largest, followed by the $F_1$ and BSB groups. The tolerances for high and low water temperature were significantly different for each species and growth stage. The largest tolerance spectrum was observed in the BSB group, and the tolerance spectrums gradually decreased with increasing final body weight. During the salinity tolerance trials, all of the species started to die following transfer into freshwater (0 psu). BSB showed the highest survival rate when kept in fresh water for an average of 29.9 hours, while the $F_1$ fish were more tolerant than the RSB fish. The fish were increasingly tolerant to fresh water and changes in water temperature as they grew, while the size of the temperature spectrum remained unchanged but shifted to a lower temperature range with growth. Our results demonstrate that $F_1$ performed well in terms of growth compared to parental fish, with higher temperature and salinity tolerances than RSB, and is thus suggested to be a suitable aquaculture species for Korea and northeast China.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.319-327
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• 2015

The present study was carried out to develop biological criteria for aquatic ecosystem health assessment using composition and diversity of collected species. The sampling sites were a total of 67 sites in the Han River (29 sites) and the Nakdong River (38 sites), May and September 2012. During the survey period fish were collected totally 93 species. In each water system, 73 and 61 species were collected in the Han River and the Nakdong River respectively. The current composition of fish species between the Han River and Nakdong River showed similar pattern. The dominant species was Zacco platypus of the Han River, and the Nakdong River was Opsariichthys uncirostris. In particular, ecological characteristics of O. uncirostris frequently appeared in general polluted waters. In conclusion, in the Nakdong River, average value of FAI (Fish Assessment Index) was averaged 41.3, indicating a "poor condition", and the Han River was 53.1, indicating a "poor condition". The aquatic health of the Nakdong River assessed based on FAI was considered to be worse than that of the Han River.

• Korean Journal of Environmental Agriculture
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• v.3 no.1
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• pp.30-35
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• 1984

A freshwater fish carp(Cyprinus carpio) was exposed to two organophosphorus insecticides in laboratory to investigate the potential of its bioconcentration. The results are summarized as follows: Bioconcentration factor of diazinon and fenitrothion after 24-hour exposure at 1 ppm concentration was 31 and 57, respectively, for the whole fish. The factor varied among different tissues of the fish in the decreasing order of viscera>rests>gills>muscle. When the fish was exposed to fenitrothion for 28 days at three different concentrations of 6, 30 and 150 ppb, bioconcentration factor in the whole fish ranged from 96 to 138, with a decreasing tendency at higher water concentration. The pesticide was continuously absorbed by the fish, but reaching an equilibrium at the tissue concentration of about 3.5 ppm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.676-684
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• 2021

Euryhaline teleost have extraordinary ability to deal with a wide range of salinity changes. To study the seawater adaptability of rainbow trout Oncorhynchus mykiss (body weight 638±54 g, length 38.6±2 cm) to salinity increase fish were transferred from freshwater to 7, 14, 21, 28 and 32 psu and checked for mortality over 5 days. No mortality was observed in 0-32 psu. In fish transferred to 0-32 psu, blood osmolality was maintained within physiological range. The changes of serum enzyme activities (aspartate transaminase, AST and alanine transaminase, ALT) showed no significant level during experimental period. To explore the underlying molecular physiology of gill and kidney responsible for body fluid regulation, we measured mRNA expression of five genes, Na⁺/K⁺/2Cl^- cotransporter1 (NKCC1), aquaporin3 (AQP3), cystic fibrosis transmembrane conductance regulator (CFTR), glucocorticoid receptor (GR) and growth hormone receptor (GHR) in response to salt stress. Based on our result, rainbow trout could tolerate gradual transfer up to 32 psu for 5 days without mortality under physiological stress. This study suggests to alleviate osmotic stress to fish, a gradually acclimation to increasing salinity is recommended.

• Development and Reproduction
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• v.24 no.4
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• pp.307-316
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• 2020

The purpose of this study is to observe the early life history of Korean Lefua costata and use the result as basic taxonomic research data for balitorid fish. The fertilized eggs were light green color with completely circle shape and mean size was 1.21±0.06 mm (n=30). Immediately after hatching, the size of the larvae was 2.81±0.11 mm (n=5) in mean length, with egg yolk. On the 3rd day after hatching, the preflexion larvae had a mean length of 4.64±0.09 mm (n=5), and their mouth was opened to start feeding. On the 8th day after hatching, a mean length of the postflexion larvae was 9.43±0.46 mm (n=5), the distal part of the notochord was bent to 45°, and 16 fin rays were developed on the caudal fin. On the 31st day after hatching, a mean length of juveniles was 22.3±0.85 mm (n=5), and the number of fin rays was the same as that of adult fish with (iv8) dorsal fins and (iii8) anal fins.

• Parasites, Hosts and Diseases
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• v.34 no.2
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• pp.95-106
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• 1996

The infestation rates and abundances of human infecting metacercariae (Clonorchis sinensis, Metcgonimus spry. , Centrocestus crmatus, Echinostoma hortense, Echinochusnus japonicw, Clinostomum complanctum) in freshwater fish were investigated at the three river areas - Taewhagang (river), Hyongsangang (river), Nakdonggang (river) - in Kyongsang-do and at four streams - Yonpungchon, Munsanchon, Kyonganchon, and Konjiamchon- in Kyonggi-do, Korea in 1994-1995. The fish caught at Taewhagang were heavily infested with metacercariae of Clonorchis sinensis and Centrocestw armctus. At Hyongsangang, Zncco platypus and Z. temmincki were moderately infested with metacercariae of C. crmctus. Chomanpo, at the basin of Nakdonggang, was still endemic for C. sinensis. In the fish caught at four streams of Kyonggi-do, metacercariae of C. sinensis exhibited the highest infestation rate and intensity out of 6 species of metacercariae. The infestation intensity of C. sinensis metacercariae in fish flesh was markedly different according to each division of flesh. The cause of this difference was conjectured as a result of larval behavior. The metacercariae of C. omnt5 were found in almost all parts, except scales and fins, of fish. The infestation rates and intensities of C. sinensis and C. armntus metacercariae in Taewhagang greatly increased as compared with those of previous reports . RhinoBobius bmnneus and Aconthorhone5 macropterus are newly recorded intermediate hosts of Echinostonn hortense. The reason of large differences from previous data was discussed and the standard method of metacercaria examination was proposed.

• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.97-104
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• 2008

Comparative study of retinal structure in two Korean endemic freshwater fishes, Zacco koreanus and Pseudobagrus koreanus, was carried out by light and scanning electron microscopy. In the visual cell layer comprised of cone cells and rod cells, the cone cells showed a distinct difference between both species. Z. koreanus had two types of cone cells, single cone cells including a long single and short single cone cells, and double cone cells, whereas P. koreanus had only one type of single cone cells having no its short single and long single cones. Meanwhile, the cone cells of Z. koreanus were arranged in more compact-rowed pattern, but it was more loose and irregular in P. koreanus. Based on field observation, Z. koreanus is mainly a epipelagic or sometimes benthopelagic and a diurnal fish with a round and large eye, while P. koreanus is a demersal and nocturnal fish with an oval and small eye. Therefore, the difference in the retinal structure of two species seems to be closely related to their ecological habitats.

• Parasites, Hosts and Diseases
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• v.56 no.5
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• pp.501-507
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• 2018

We described here the morphological characteristics for the species identification and fish hosts of Isoparorchis sp. (Digenea: Isoparorchiidae) in the Republic of Korea (Korea). Total 1,371 freshwater fishes collected in Yangcheon (Stream) in Sancheong-gun, Gyeongsangnam-do were examined by the artificial digestion methods to survey the infection status of digenetic trematode metacercariae for 4 years (2013-2016). Adult and larval worms of Isoparorchis sp. were detected in 38 (8.4%) out of 451 fish in 4 species, i.e., Pungtungia herzi, Acheilognathus koreensis, Squalidus japonicus coreanus and Odontobutis platycephala, examined. The infection density was 1.1 worm per fish infected. They were mainly found in the subcutaneous tissues and abdominal cavities. Nodules with worms in the subcutaneous tissues were revealed as the blue ink-colored bulges. Adults leaf-like, $21.6{\times}9.84mm$ in average size. The ratio of body length to body width was 2.20: 1. Oral sucker subterminal, $1.03{\times}1.22mm$. Pharynx muscular, $0.55{\times}0.54mm$. Esophagus very short. Ceca convoluted, terminated near the posterior end. Ventral sucker anterior 1/3.75, $1.99{\times}2.10mm$. The ratio of ventral sucker to oral sucker was 1.74: 1. Testes round to elliptical, both sides of ventral sucker, $1.43{\times}1.33mm$. Vitellaria highly dendritic, posterior 1/3 level. Eggs operculated, embryonated, $52{\times}32{\mu}m$ in size. By the present study, 4 fish species aforementioned are to be listed as the fish hosts of Isoparorchis sp. in Korea and additionally the morphological characteristics are to be described for the species identification.

• Parasites, Hosts and Diseases
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• v.59 no.3
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• pp.265-271
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• 2021

We surveyed on the infection status of zoonotic trematode metacercariae (ZTM) in freshwater fishes from Soyang-cheon (a branch stream of Mangyeong-gang) in Wanju-gun, Jeollabuk-do, the Republic of Korea. A total of 927 fishes were individually examined with the artificial digestion method during 2013-2015 (462 fish in 15 spp.) and 2018-2019 (465 fish in 25 spp.). Clonorchis sinensis metacercariae were detected in 207 (31.4%) out of 659 fishes in 14 positive fish species (PFS), and their mean intensity was 114 per fish infected (PFI). Metagonimus spp. metacercariae were found in 302 (37.4%) out of 808 fishes in 21 PFS, and their mean intensity was 12 PFI. Centrocestus armatus metacercariae were detected in 222 (59.0%) out of 376 fishes in 12 PFS, and their mean intensity was 383 PFI. Echinostoma spp. metacercariae were found in 139 (22.1%) out of 628 fishes in 10 PFS, and their mean intensity was 7 PFI. Clinostomum complanatum metacercariae were detected in 14 (6.5%) out of 214 fishes in 4 PFS, and their mean intensity was 2.4 PFI. Metorchis orientalis metacercariae were detected in 36 (13.5%) out of 267 fishes in 5 PFS, and their mean intensity was 4.3 PFI. Conclusively, the prevalence and infection intensity of ZTM is generally not so high in fishes from Soyang-cheon. However, those of C. sinensis metacercariae are more or less higher in 2 fish species, Pungtungia herzi and Sarcocheilichthys variegatus wakiyae.