• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.89-95
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• 2000

Two species of the genus Koreocobitis in Korea are reviewed with a key to species and their illustrations: Koreocobitis rotundicaudata and K. naktongensis sp. nov. A new species, Koreocobitis naktongensis is described based on 9 specimens collected from the Naktong River, Korea. The new species is distinguished from Koreocobitis rotundicaudata by the following combination of characters: yellow body colouration with many brownish speckles, truncate caudal fin, fewer vertebrae, and longer head. It is remarked biogeographically that Koreocobitis naktongensis is distributed only in the Naktong River, Korea.

• 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.

• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.234-241
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• 2011

Habitat, reproduction and feeding habit of endangered fish Koreocobitis naktongensis from Jaho stream, Gyeongsangbuk-do, Korea were investigated from March 2010 to June 2011. This species inhabits at the upper and middle parts of stream, which were composed of cobbles and pebbles bottom. The current velocities in these microhabitat were 5~10 cm/sec and depth were 50~110cm. The sex ratio of female to male was 1 : 0.92. It is presumed that the spawning season is from May to June when water temperatures were 17 ~ 20$^{\circ}C$. The average number of mature eggs in ovary were about 22,643 (15,909~30,323), mean egg diameter was 0.87${\pm}$0.05mm. K. naktongensis fed mainly on Chironomidae (IRI, 72.0%) and Ephydridae (26.9%) of Diptera.

• Korean Journal of Ichthyology
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• v.21 no.4
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• pp.247-252
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• 2009

The egg development and early life history of the Korean endangered fish Koreocobitis naktongensis (Cobitidae) were investigated. Eggs from the females were obtained by injecting 10 IU/g of human chorionic gonadotropin and inseminated with sperm by the dry method in the laboratory. The fertilized eggs were 1.0~1.2 mm in diameter and had no oil globules. The embryo began to hatch about 38 hrs after fertilization under water temperature of $20{\pm}1^{\circ}C$. The newly-hatched larvae were 2.6~2.8 mm in total length, and their mouth and anus were not yet opened. Seven days after hatching, the postlarvae were 4.5~5.2 mm in total length, and their yolk sacs were completely absorbed. They entered the juvenile stage when all fin-rays were formed at 50 days after hatching, and their total lengths were 21~27 mm.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.71-80
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• 2016

The fauna of freshwater fish and water chemistry characteristics were investigated from June, 2014 to October, 2014 at 10 sites in Taebaeksan Provincial Park. A total of 7 species under three families were collected from the survey sites and among them one endangered species - Koreocobitis naktongensis - was identified. The endemic species of Korea were 2 species: Koreocobitis naktongensis, Iksookimia koreensis. Dominant species was Rhynchocypris oxycephalus(89%) and subdominant species was Orthrias nudus(8.9%). Water quality including conductivity, turbidity, pH and total dissolved solids(TDS) varied largely depending on the sampling locations. Values of ambient conductivity and TDS were greater in the upstream than in the downstream, and seasonal variabilities were also higher in the upstream. The pH decreased towards the downstream, and especially showed a sharp decrease in S5. This phenomenon was evident due to a dilution by the influx in the acid mine drainage(AMD) of S4. Physical habit conditions, based on qualitative habitat evaluation index(QHEI) model, indicated a "Sub-optimal" condition(mean: 157.3; range: 78 ~ 194) in the Sodo stream watersheds.

• Korean Journal of Ichthyology
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• v.21 no.sup1
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• pp.7-28
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• 2009

The family Cobitidae of Korea was reviewed as 16 species in 5 genera with the key to species for the identification by the external features. The three genera of Iksookimia, Koreocobitis, and Kichulchoia erected from the genus Cobitis were reclassified based on the presence or absence of Gambetta’s zones on the body sides, their body pigmentation, the shape of lamina circularis in males, the number of unbranched anal fin rays, and some molecular phylogenetic data. By the results of these reexamination, the generic names of the three species were changed as Cobitis choii, Iksookimia pacifica, and Kichulchoia mutifasciata. It was remarked biogeographically that most species of genera Cobitis, Iksookimia, Koreocobitis, and Kichulchoia show the disjunct distributions with bottom-dwelling preferences as endemic to Korean peninsular. Three species of Cobitis choii, Kichulchoia brevifasciata, and Koreocobitis naktongensis are considered to be critically endangered according to the severe habitat destruction and the alteration of river topography.

• Korean Journal of Environment and Ecology
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• v.25 no.6
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• pp.878-886
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• 2011

The fish fauna and characteristic of population of Brachymystax lenok tsinlingensis at the 7 stations in the Bonghwa-gun were investigated from June 2010 to May 2011. The collected species during the survey period were 15 species belong to 7 families. Protected species by the legal were B. lenok tsinlingensis, Koreocobitis naktongensis, and Cottus koreanus. Korean endemic species were Microphy sogobio yaluensis, Coreoleuciscus splendidus, Zacco koreanus, Cobitis hankugensis, K. naktongensis, Iksookimia longicorpa, Niwaella multifasciata, Liobagrus mediadiposalis, C. koreanus, and Coreoperca herzi, which showed a ration of 66.7% in collected species. Dominant species were Z. koreanus(St. 1), B. lenok tsinlingensis(St. 3, 4, 5), and Rhynchocypris oxycephalus(St. 2, 6, 7). Length-weight relation in the population of B. lenok tsinlingensis was BW = $0.000008TL^{3.02}$, and condition factor in the population was average 0.84. Frequency analysis of total length indicated that the group 80~180 mm in total length is represented by one-year-old individuals, the group 200~300 mm by two-year-old individuals, and the group over 300 mm by three-year-old individuals. The density of population was presumed average 17 individuals per 100$m^2$ and total 4,760 individuals in the reservation for B. lenok tsinlingensis.

• Environmental Engineering Research
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• v.24 no.4
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• pp.638-645
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• 2019

This research was an evaluation of the fish fauna and the habitat for Brachymystax lenok tsinlingensis (B. lenok tsinlingensis) for 11 stations at the Bonghwa-gun sanctuary. The predominant species in this research area was Zacco koreanus. B. lenok tsinlingensis, which has been designated as an endangered freshwater fish in Korea, was found in the Bonghwa sanctuary zone, except at stations 5 and 6. The B. lenok individuals were shorter in length than 400 mm. In total, 13 endemic species were found, including Coreoleuciscus splendidus and Iksookimia longicorpus. Specimens of Koreocobitis naktongensis, a first grade endangered species, were also collected. The benthic macroinvertebrates consisted of four divisions, four classes, seven orders, 30 families, 60 species, and 10,344 individuals and were distributed among the orders Ephemeroptera (55.9%), Diptera (18.2%), Trichoptera (12.4%), Plecoptera (2.1%), and Odonata (0.3%).

• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.50-69
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• 2014

Freshwater fish fauna and community structure were investigated at thirty seven stations in the Yeong river, Nakdong river system, Korea from March to October 2013. During the surveyed period thirty nine species and two types belonging to thirteen families were collected. In this collection fishes of Cyprinidae were most numerous possessing 61.0% of all. There were seventeen Korean endemic species including Acheilognathus koreensis, two endangered species such as Koreocobitis naktongensis and Microphysogobio koreensis and two exotic species such as Oncorhynchus mykiss and Micropterus salmoides. Fish species transferred from other native rivers were three species such as Opsariichthys uncirostris amurensis, Pseudobagrus koreanus and Hypomesus nipponensis. Dominant species based on the number of individuals was Zacco koreanus NS (23.24%) and sub-dominant species were Z. koreanus NE (12.72%) and Z. platypus R (12.35%). The community analysis revealed that the structure of fish community in the Yeong river was very stable and diverse in having diversity 1.134, evenness 0.703, dominance 0.110 and species richness 4.348. Fish community was divided into four groups based on similarity indices among surveyed stations such as upper reach, mid-upper reach, middle reach and lower reach group.

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.116-132
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• 2015

Freshwater fish fauna and community structure were investigated at 44 stations in upper reach of the Nakdong river, Korea from March to October 2014. During the surveyed period 42 species and 4 types belonging to 34 genera and 14 families were collected. In this collection fishes of Cyprinidae were 17 species and 4 types, most numerous possessing 43.2% of all. There were 17 Korean endemic species including Kichulchoia multifasciata, 3 endangered species such as Koreocobitis naktongensis, Lethenteron reissneri and Brachymystax lenok tsinlingensis and 2 exotic species such as Lepomis macrochirus and Micropterus salmoides. Fish species transferred from other native rivers were 9 species including Hemibarbus mylodon, Coreoleuciscus slpendidus Han river type, Opsariichthys uncirostris amurensis, Iksookimia koreensis and Liobagrus andersoni. Dominant species based on the number of individuals was Rhynchocypris oxycephalus (21.44%) and sub-dominant species were Zacco koreanus NE type (18.55%). The community analysis revealed that the structure of fish community in upper reach of the Nakdong river was very stable and diverse in having diversity 1.101, evenness 0.670, dominance 0.400 and species richness 4.454. Fish community was divided into 5 groups based on similarity indices among surveyed stations such as uppermost, upper I, upper II, mid-upper, middle reach group.