• Applied Microscopy
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• v.28 no.1
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• pp.63-71
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• 1998

The spermatozoon of Squalidus gracilis majimae is approximately $36.6{\mu}m$ in length and is characterized by a spherical nucleils with the clear chromatin, a short midpiece containing the mitochondria, and a flagellum positioned tangentially to the nucleus. An acrosome is absent as in all teleost fishes. The nucleus is about $1.9{\mu}m$ in diameter and in its periphery contains the electron-lucent chromatin distinguished from the electron-dense chromatin occupying most of the nucleus. The shallow nuclear fossa contains the proximal centriole, instead of two centrioles in deep nuclear fossa in siluroids. The proximal and distal centrioles are oriented approximately $140^{\circ}$ to each other. The mitochondria of 10 or more in number are arranged in three layers and do not surround the axoneme. The asymmetrical distribution of the mitochondria and the eccentrical position of the nucleus with regard to the tail are the general pattern of the cyprinid spermatozoa. S. gracilis majimae spermatozoa have the most mitochondria and the deepest cytoplasmic canal among cyprinid species. The flagellum lacks the lateral fins.

• Korean Journal of Ichthyology
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• v.21 no.3
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• pp.208-213
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• 2009

Histological examination of an individual of the Korean slender gudgeon Squalidus gracilis majimae having cutaneous albinism produced rarely in the wild was made and compared with a normal individual. The external body of the albino was colorless, differing from the normal individual, which has dense brownish black spots over its body surface. To make it clear through histological study, we observed eight skin regions: dorsal, lateral, ventral, upper caudal peduncle, lower caudal peduncle, dorsal fin, anal fin, and the eyes. These regional skins were the same in fundamental structure between albinic and normal gudgeon, but there were significant differences in distribution and development of pigment cells (melanins). In the normal gudgeon, the pigment cells were well developed over the regional skins except on the skin from the ventral region. However, it was confirmed in the albino that the pigment cells were vestigial over the upper regions of the eye and body but absent in the ventral region, lower caudal peduncle, and anal fin.

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.207-216
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• 2005

Spawning behaviors of Squalidus gracilis majimae (Cyprinidae) were observed in the laboratory whose environmental factors such as light (D/L = 16 : 8), temperature ($20\;{\sim}\;24\;＾{\circ}C$), and dissolved oxygen (>8 mg $L^{-1}$) were quite regularly controlled. The behavioral patterns were categorized into three stages ofpre-spawning, spawning, and Post-spawning behaviors. In Particular, the pre-spawning stage was specified by 11 specific behavioral patterns of aggressive mating behaviors. During the spawning stage, the male and female performed four distinct spawning behaviors including sexual temptation, stimulation, egg spawning, and the separation, and randomly laid about 200 ${\sim}$ 300 eggs on the bottom substrates through the night. After finishing spawning, two adults separated toward their refuges and showed 3 types of post-spawning behaviors such as the resting, occasional eggs protecting, and the egg eating. The fish was identified as a partial-parental care species after the spawning.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.132-138
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• 1984

The genus Squalidus of Korea, formerly regarded as genus Gnathopogon is reviewed and keys to following 4 species and subspecies: S. gracilis majimae, S. chankaensis tsuchigae, S. chankaensis ssp., and S. japonicus coreanus. The genus spualidus is distinguished from genus Gnathopogon by the position of snout, color pattern on the body sides, number of scales above lateral line, and distance from anus to anal finorgin. G. majimae Jordan et Hubbs is junior synonym of S. gracilis majimae, and G. coreanus (not Berg) is splitted and identified as S. chankaensis tsuchigae, S. c. ssp., and S. japonicus coreanus. S. c. tsuchigae is very similar to S. j. coreanus, but the eye diameter, barbel length, and the number of lateral line scales are useful characters in separating these species. S. thankaensis ssp. occurring only in the Yongdok-Oship River differs from S. chankaensis tsuchigae in the number of lateral line scales, eye diameter and their body size.

• Korean Journal of Ichthyology
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• v.34 no.4
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• pp.244-252
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• 2022

The aim of this study was to investigate the early life history of Squalidus gracilis majimae by observing the development of the eggs and morphology of juvenile fish. Squalidus gracilis majimae used in this study were captured in 2021 June from a tributary flowing into Wicheon, located in Uiseong-gun, Gyeongsangbuk-do. For artificial insemination, ovaprim was injected at 0.5 mL/kg. Egg development occurred 12 h after injection. The size of mature eggs of S. gracilis majimae was 0.80~0.85 mm (0.83±0.01 mm, n=30). Incubation time at 22±1℃ ranged from 62.5 to 69 h. The length of larvae immediately after hatching was 2.39~2.53 mm (2.44±0.04 mm, n=30). On the 18th day after hatching, the larvae had a total length of 8.51~9.84 mm (8.95±0.42 mm, n=30), and the tip of the spine was completely curved. On the 22nd day after hatching, the juvenile fish had a total length of 12.6~13.6 mm (13.0±0.36 mm, n=30), with dorsal fins at iii7 and anal fins at i7. Egg size and hatched larvae size were similar for S. gracilis majimae and S. multimaculatus, and cupulae showed a singularity as it disappeared last among related species.

• Korean Journal of Ichthyology
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• v.7 no.2
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• pp.135-139
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• 1995

The ichthyofauna was investigated at the thirteen sites in the Tamjin River from August 1994 to February 1995. The collected fishes were classified into thirty-nine species belonging to 29 genera and 10 families. Among these 12 species were classified as endemic species or subspecies in Korea. Major species in this river system appeared to be Zacco temminchi, Acanthorhodeus gracilis, Zacco platypus, Rhodeus uyekii, Puntungia herzi and Squalidus gracilis majimae. Odontobutis obscura interrupta was collected for the first time in this area.

• Korean Journal of Ichthyology
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• v.4 no.2
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• pp.63-71
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• 1992

The Ichthyofauna was investigated at the seven sites in Paikchon streams from August 1990 to March 1991. The collected fishes were classified to 22 species belong to 19 genera and 11 families, of which 5 species were tentatively identified as endemic species in Korea. Three species, Odontobutis obscurus interrupta, Luciogobius guttatus and Mactopodus chinensis, are collected for the first time in this area. Dominant species were Squalidus gracilis majimae(40.8%), Zacco temmincki(24.2%), Z. platypus(13.3%) and Cobitis koreensis pumilus(7.7%). Stomach contents of S. gracilis majimae were mainly taxa belong to Bacillariophyceae of micro-algee attached to sand or gravel.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.277-284
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• 2021

This study surveyed the ecological characteristics of Squalidus gracilis majimae at Nakdong River tributary Sinan Stream from January to December 2020. The species inhabited the riverbed that was mostly covered with gravel and sand. The water depth was 27-158 cm, and the average was rather deep at 54 cm. The stream velocity was slow at 0.41±0.19 (0.24-0.86) m/sec. The gender ratio of females to males was 1:0.73. According to the total length-frequency distribution, the age indicated that the group with less than 50 mm in total length was one year old, the group with 70-69 mm was two years old, and the group over 70 mm was three years old. The total length of sexually mature fishes was 50 mm for females and 60 mm for males. The spawning season was from June to July, and the water temperature was 20.9-23.4℃ during the period. The prosperous spawning season was July. The average number of eggs in the ovaries was 1,009 (595-1,630) per matured female, and the matured eggs were yellowish and spherical with a mean diameter of 0.78±0.08 (0.57-0.83) mm. The live foods were S. gracilis majimae Protozoa, attached algae, zooplankton, and aquatic insects. The feeding habits of S. gracilis majimae are omnivorous, but more than 80% of the stomach content was aquatic insects, Chironomidae spp. The larger the size of this species, the greater the amount and frequency of eating aquatic insects, which are animal feeds. The population that ate aquatic insects did not eat vegetable food.

• Korean Journal of Environment and Ecology
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• v.16 no.4
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• pp.403-408
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• 2003

Fishfauna were investigated in the Baekdudaegan Mountain area (Manbokdae-siribong) streams. At the uppertributary of Seomjin River, 17 species of 5 families were collected and the dominant species was Zacco temminki. Korean endemic species were six (35.3%) species, Acheiognathus koreensis, Coreoleuciscus splendidus, Squalidus gruacilis majimae, Microphysogobio yaluensis, Iksookimia longicorpus, and Odontobutis platycephala. Only Lampetra reissneri designated as a vulnerable species, was confirmed at the stream. At the upper streams of the Nakdong River, collected fishes were identified as 11 species of 3 families. The dominant species was Zacco temmincki, and two species (18.2%), Squalidus gracilis. majiimae and Ikosokimia longicorpus were Korean endemic.

• Korean Journal of Ichthyology
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• v.10 no.1
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• pp.77-86
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• 1998

The ichthyofauna and the structure of fish community were surveyed from August 1995 to October 1997 at twenty one stations in the Wicheon river which is a first tributary located at the middle reach of the Nakdong river system. During the surveyed period, 40 species belonging to ten families were collected. Of them cyprinid fish occupied 65.0% (26 species) and cobitid fish 12.5% (5 species). Sixteen species (40.0%) were known as Korean endemic species. Dominant species were Zacco temmincki (15.35%), Zacco platypus (14.12%), and Squalidus gracilis majimae (11.32%). Rare species which occupied less than 0.1% of total individuals were Cyprinus carpio, Culter brevicauda, Misgurnus mizoiepis, Cobitis rotundicaudata, Leiocassis ussuriensis, Silurus asotus, Macropodus chinensis, and Channa argus. A tendancy were shown in regional distribution that Moroco oxycephalus dominated in upper stream, Zacco temmincki, Squalidus gracilis majimae, and Niwaella multifasciata in mid - upper stream, acheilognathid fishes and Zacco temmincki in mid - lower stream, and Zacco platypus and microphysogobioid fishes in lower stream. St. 9, 10, and 11 which located in mid - reach of main stream and St. 17, 18 and 19 which located in mid - reach of the Ssanggye stream had the most stable and diverse community structure.