• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.90-96
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• 2008

The histological morphology on the skin of Misgurnus anguillicaudatus was described in the three regions such as dorsal, lateral, occiput and subsequently morphological variations of the skin were monthly observed for a year. The skin consisted of epidermis having epithelial cell, club cell and mucus cell, and dermis of mainly connective tissue fiber, embedded scale and blood capillary. Unicellular mucus cells situated at the epidermis underwent seasonal change in its size, as well as number and amounts of mucus-secreting materials, which they greatly increased in winter, but did not in summer. As it is getting cold, the mucus cells' shape changed from initial spherical to oval or elongated form. Such considerable changes in the mucus cell were particularly most evident in the occiput during winter. Moreover, the dermis largely thickened about 2~3 times in winter than in summer. Based on these results, we discussed function for the mucus on what it mainly acts in nature and information on whether mucus cells' seasonal variations affect on hibernation and cutaneous respiration.

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.119-124
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• 2018

Diversity of fish fauna and species list collected from the Imha-Dam Reservoir of the Nakdonggang River system were reviewed based on the published materials from 1992 to 2016. As a result of the present study, 46 freshwater fish species/subspecies belonging to 36 genera, 11 families, 4 orders were reported in the Imha-Dam Reservoir. Of them, Cyprinidae occupied 58.7% (27 species), Cobitidae 10.9% (5 spp.), Gobiidae 6.5% (3 spp.), and Siluridae, Centropomidae, Centrarchidae were 4.3% (2 spp.) in the number of species, respectively. The dominant species in the number of individuals was Erythroculter erythropterus (40.1%, 9,333 inds.), and the subdominant species was Opsariichthys uncirostris amurensis (9.8%, 2,281 inds.). Among 46 species/subspecies, 17 species (37.0%) were identified as endemic species to Korea. Three species were endangered fish species by the Ministry of Environment of Korea, five translocated species, and three exotic species were reported.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.145-149
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• 2011

We studied any variations of skin mucus cells of Misgurnus mizolepis caused by inducing a great change of water temperature including high temperature- and low temperature-adapted groups and then compared them with a control group of normal water condition. The high temperature-adapted group showed no significant different in size and number of the mucus cell (P>0.01), whereas in the low temperature-adapted group, the surface area of mucus cell layer and shape of its mucus cell, and the number of mucus cell remarkably increased in all the skin regions of dorsum, lateral region and occiput (P<0.01). Returned to the same condition as the control group, the low temperature-adapted groups showed the same features that appear in the normal water condition (P<0.01). Based on these results, the skin mucus cells of M. mizolepis seems to be very sensitive to cold water temperature and therefore they may play a key role in assessment of its environmental conditions.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.47-54
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• 2009

The ichthyofauna and fish community were surveyed at eight stations in the Wangpi stream from July 2007 to Jun 2008. During the survey period 23 species belonging to 9 families were collected. Of them cyprinid fishes comprised 47.8% (11 species), and Gobiidae 13.0% (3 species), Cobitidae 8.7% (2 species), Siluridae 8.7% (2 species) and other 4.2% (1 species). Eight species (34.8%) of observed species were endemic species. The dominant and subdominant species were Zacco koreanus (relative abundance : 31.0%) and Pungtungia herzi (relative abundance : 27.4 %). As the result of analyzing fish community in the surveyed area, the species diversity, evenness and dominant indicated that the community structure was similar between the upper and lower area of Wangpi stream.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.15-22
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• 2009

An artificial breeding method was carried out to investigate development of eggs and the early life history of Iksookimia longicorpa. The eggs of the female were obtained by injecting gonadotropin (LHRH) and fertilizingby the dry method in the laboratory. The mature eggs were separate, demersal, light yellowish, and averaged $1.53{\pm}0.07mm$ in diameter. In water temperature of $23{\sim}25^{\circ}C$, the eggs hatched in 50~72 hours after fertilization, and their lengths reached $5.1{\pm}0.23mm$ in total length. On Day 4 after hatching, they averaged $7.1{\pm}0.47mm$ in total length and their yolk sacs were completely absorbed. From 25 days after hatching, they attained a juvenile stage reaching $12.8{\pm}0.49mm$ in total length. On the 100th dayafter hatching, their band patterns and external form were similar to those of adults, and they averaged $38.5{\pm}2.95mm$ in total length.

• Korean Journal of Ichthyology
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• v.21 no.2
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• pp.87-92
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• 2009

Histological investigation of seasonal changes of the mucus cells of ricefield-dwelling mud loach Misgurnus mizolepis was carried out on the skin in three regions of the fish: dorsal, lateral, and occipital. Although there were no significant differences in general morphology, the mucus cells of the epidermis showed a severe change in size and number by skin region. The density of the mucus cells was generally the highest in winter and the lowest in summer in all three skin regions. In particular, during two distinct periods, March to April when water is supplied to the ricefields, and August to September when the ricefields become dry after harvest, showed that the change in density and distribution of the mucus cells in both lateral and occipital regions is greater than during any other period. Moreover, the mucus cells for the dorsal and occipital regions temporally increased in size in June during the period of the highest water temperature of the year. Therefore, we may consider these seasonal changes as part of a protective adaptation to overcome extreme environmental conditions and to increase uptake of oxygen by cutaneous respiration.

• Korean Journal of Ichthyology
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• v.31 no.2
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• pp.101-109
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• 2019

This study investigated the characteristics of fish communities at the Lake Yedang, in 2013 to 2014 and 2017. During the survey period, there were 29 species of 10 families collected from 3 survey stations. Of them, Cyprinidae occupied 34.5% (14 species), Bagridae, Gobiidae 10.3% (3 species), and Cobitidae, Centrachidae were 6.9% (2 species) in the number of species, respectively. Korean endemic species were 4 species (13.8%) Abbottina springeri, Cobitis nalbanti, Pseudobagrus koreanus, Odontobutis interrupta and accounted for a low rate. There were 3 species (10.3%) exotic species including Carassius cuvieri, Lepomis macrochirus, Micropterus salmoides. As a result of community analysis, dominant index was 0.45~1.00, diversity index was 0.19~2.30 and richness index was 0.41~1.94.

• Animal Systematics, Evolution and Diversity
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• v.9 no.2
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• pp.151-170
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• 1993

Morphometric, band-pattern and electrophoretic analysis on Cobitis taenia complex were performed to investigate the morphological and genetic differentiation and to clarify their taxonomic status. Intermediate types of band-pattern (C and D type) were more frequently expressed than that of types of C. t. taenia(type A) and C. t. lutheri (type B). Sexual dimorphism of band-pattern was observed not only in C. t. taenia(type A) and C. t. lutheri(type B). Sexual dimorphism of band-pattern was observed not only in C. t. lutheri but also in C. t. taenia and C. t. striata as well. Discriminant function analysis based on 19 morphological characters shows no significant differences among C. taenia complex. The degree of genic variation of C. t. striata was higher ( =1.48, P=31.2%, HD=0.009) than those of C. t. striata was higher( =1.48, P=31.2%, HD=0.082 and HG=0.009) than those of C. t. lutheri ( =1.37, P=2.7%, HD=0.058 and HG=0.065). The average genetic similarities between C. t. lutheri and C. t. taenia-C. t. striata were S=0.62 and S=0.66 respectively and these values indicate that C. t. tanenia has evolved specific level of differentiation. C. t. striata and C. t. lutheri show subspecifc level of close genetic similarity (S=0.82). Based on the divergent time estimate (Nei, 1975) it is assumed that C. t. tanenia was branched off from the other subspecies about two million years before present (MYBP) and C. t. striata and C. t. lutheri were differentiated about 0.6 MYBP. The use of C. sinesis an the scientific name for the Korean C. t. taenia, proposed by Kim and Lee (1988) seems incorrect since they are quite different in the structure of lamina circularis (Vladycov, 1935), the external morphology and distribution (Cheng and Zheng, 1987) and the chromosome number(Yu et al., 1989). Kim and Lee(1988) also argued that C.t. striata and C. t. lutheri should be treated as distinct species but the present study and other reports (Kim and Lee, 1984; Kim and Yang, 1993) do not support it. We conclude that C. t. taenia is a good species and C. t. striata and C. t. lutheri are subspecific status. Their scientific names should be revised in the future.

• Korean Journal of Ichthyology
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• v.36 no.1
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• pp.48-57
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• 2024

Distribution status and extinction threat evaluation of an endangered species, Cobitis choii, were investigated from 2015 to 2019. In 2015 and 2018, we investigated past appearance sites of C. choii. In 2015, 163 individuals from nine sites were collected by surveying 19 stations. In 2018, 19 individuals from five sites were collected by surveying 22 sites. In 2019, 156 individuals from 12 sites were collected as a result of a survey of 79 sites of past appearance and potential appearance of C. choii. Appearance regions were Mihocheon (Baekgokcheon (2 sites), Chopyeongcheon (1 sites)), Gapcheon (3 sites), Yugucheon (2 sites), Jicheon (4 sites), and Geumgang mainstream (2 sites). Among these appearing regions, Baekgokcheon, Yugucheon, and Mihocheon mainstreams showed a sharp decline in population. Baekgokcheon was estimated to have a habitat change due to a project to raise the bank of Baekgok Reservoir. Yugucheon was estimated to have a habitat disturbance due to flood-induced collapse and reconstruction of weir. Mihocheon mainstream was estimated to have water pollution and habitat disturbance. On the other hand, Chopyeongcheon and Geumgang mainstream were newly habitat identified and Gapcheon was noted to show an increase in the number of individuals. After performing extinction threat evaluation, C. choii was evaluated as Endangered (EN A2ac) due to its rapid population decline (more than 50%) in its habitats of Baekgokcheon, Yugucheon, and Mihocheon based on criteria A, while it was evaluated as Vulnerable (VU B1ab (iii,v) +B2ab +B2ab (iii,v)) due to its narrow extent of occurrence (EOO, 1,735 km²) and area of occupancy (AOO, 36 km²) in 6 locations with a continuous population decline based on criteria B. Therefore, the final threat of extinction grade was evaluated as Endangered (EN A2ac). In Baekgokcheon, Yugucheon, and Mihocheon mainstream where the population has declined rapidly recently, conservation measures are urgently required to increase its population.

• Korean Journal of Ichthyology
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• v.32 no.2
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• pp.49-54
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• 2020

The morphometry and morphology of the olfactory organ of the southern king spine loach Iksookimia hugowolfeldi were investigated by stereo microscopy and statistical analysis. Its external morphology consists of two holes, the anterior and posterior nostrils. The anterior nostril (0.35~0.53 mm in diameter) forms tubular process protruding vertically from each side of the snout. The posterior nostril (0.32~0.68 mm in major diameter) is a eye-like hole parallel to the skin. Internally, the rosette structure is set with 14 to 21 lamellae and medium raphe on the inner floor. In morphometry, its lamellar number (male vs. female; 18±1.8 vs. 17±1.6, P<0.05) and lamellar number to standard length ratio (24.2±1.3% vs. 21.7±2.5%, P<0.05) was larger in male than female. The lamellar number and standard length have high correlation in male (P<0.001) but not in female (P=0.170). It seems that such characteristics of the olfactory organ of I. hugowolfeldi are related to its bottom-dwelling life which digs and takes a rest under sand and sexual dimorphism by a distinct degree in olfactory dependence for reproduction of each sex.