• Korean Journal of Ichthyology
• /
• v.2 no.2
• /
• pp.117-137
• /
• 1990

The morphological characters of the family Bagridae living in the river systems flowing into the south and western seas of Korea were reviewed and a taxonomic revision was made. The family Bagridae was classified into two genera: Pseudobagrus and Leiocassis. Species corresponding to genus Pseudobagrus were P. fulvidraco, P. koreanus Uchida, sp. nov., P. brevicorpus, and genus Leiocassis were L. nitidus, L. ussuriensis, and L. longirostris. Among them Pseudobagrus koreanus Uchida, sp. nov. and P. brevicorpus are endemic species of Korea. As the intergeneric taxonomic characters, the outstanding morphological differences between genera Pseudobagrus and Leiocassis were distinguished in following characters; the serrated structure of pectoral spine, the length of barbels, the number of pectoral fin rays, the structure of cranial lateral line system and the fused state of 3-4 hypurals. Pelteobagrus fulvidraco and Coreobagrus brevicorpus recorded previously in Korea were classified as Pseudobagrus fulvidraco and P. brevicorpus, respectively. Pelteobagrus nitidus and Pseudobagrus ussuriensis are also changed to genus Leiocassis. The characters of interspecific classification belonging to genera Pseudobagrus and Leiocasis were the shape of caudal fin, the form of body, the length of body, the number of anal fin ray and the number of gill rakers. Pseudobagrus sp. was named into Pseudobagrus koreanus Uchida, sp. nov..

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

• Animal cells and systems
• /
• v.11 no.2
• /
• pp.155-160
• /
• 2007

The skin of the Korean bullheads, Pseudobagrus brevicorpus and P. koreanus, is composed of epidermis, dermis and subcutis. The epidermis has three layers, the outermost layer, middle layer and stratum germinativum. The epidermis consists of two types of gland cells, an unicellular mucous cell of sulfomucin and a large club cell having sometimes two nuclei. The epidermis has numerous intraepithelial blood vessels in P. brevicorpus but not at all in P. koreanus. Lymphatic spaces containing lymphocytes are well developed in mainly the stratum germinativum. The dermis lacks scales and consists mostly of bundles of coarse collagen fibers. The collagen bundles are arranged in parallel to each other in the dorsum and lateral region toward the dorsum, but vertically at intervals in the abdomen and lateral region toward the abdomen. Considering this unique skin structure, the two species are likely to exercise cutaneous respiration as a dual respiratory system to overcome hypoxic conditions which frequently occurs in their habitats.

• Korean Journal of Ichthyology
• /
• v.34 no.3
• /
• pp.153-159
• /
• 2022

The olfactory organ of a Korean endemic species, Pseudobagrus koreanus, was investigated to describe its morphology and histology and analyze correlation between habitat environment and its ecological habits and characters, using a stereo microscope, a light microscope, and a scanning electron microscope. Its external morphology showed tubular anterior nostril at the tip of the snout and slit posterior nostril at the base of the nasal barbel. The olfactory chamber showed the rosette structure consisting of numerous lamellae radial and parallel to the medium raphe. The olfactory lamella has the sensory epithelium with olfactory receptor nuerons, supporting cells, basal cells, lymphatic cells, plasma cells and the non-sensory epithelium with stratified epithelial cells, mucous cells, lymphatic cells. In particular, 1) 41~43 (n=20) lamellae, 2) lymphatic cells and plasma cells, 3) mucous cells including neutral polysaccharid may be olfactory characteristics relevant to a stagnant or a standing habitat environment, nocturnal habit dependent on olfaction, and taxonomic characters compared at least to other catfish species.

• Development and Reproduction
• /
• v.12 no.3
• /
• pp.215-220
• /
• 2008

Sex differentiation process of the spotted Black Bullhead, Pseudobagrus koreanus, was investigated using fish samples of different age after hatching. The primordial germ cells appeared separately under air bladder in 1-day larva (total length: $6.63{\sim}6.95\;mm$). The primordial gonad with a genital ridge developed in 5-day prelarva ($7.50{\sim}9.36\;mm$). The ovarian differentiation started in about 25-day juvenile ($11.58{\sim}13.21\;mm$). The somatic tissues enlongated in the tip of one end of undifferentiated gonad and fused each other. Thus a small ovarian cavity appeared. The testicular differentiation was initiated in 30-day juvenile ($12.19{\sim}13.72\;mm$). The rudiment of sperm duct was appeared in the lower part of the undifferentiated gonad. In 50-day juvenile ($16.28{\sim}17.06\;mm$), the ovary started to fill with peri-nucleolus oocytes, and the spermatogonia started to develop. In 250-day juvenile ($35.49{\sim}51.12\;mm$), the ovary became bigger and filled with oocytes, and the number of spermatogonia started to increase. Considering these results, the spotted Black Bullhead could be a differentiated type in sex differentiation and gonochorism in sexuality.

• Korean Journal of Ichthyology
• /
• v.17 no.4
• /
• pp.271-278
• /
• 2005

The ichthyofauna and fish community were studied in Miho Stream from May 2004 to August 2005. During the surveyed period 41 species belonging to 10 families were collected. Twelve of the species (29.3%) are endemic to Korea. Exotic fishes were Carassius cuvieri, Lepomis macrochirus, and Micropterus salmoides. Dominant species was Zacco platypus (54.7%). Comparing the present result with that of Son (1982), the indices of diversity,evenness and richness were lower and the dominance index was higher; Lampetra reissneri, Anguilla japonica, Acheilognathus macropterus, Coreoleuciscus splendidus, Pseudopungtungia nigra, Gobiobotia naktongensis, Lefua costata, Pseudobagrus koreanus, Monopterus albus and Iksookimia choii did not appear; Carassius auratus, Rhodeus uyekii, Rhodeus notatus, Acheilognathus lanceolatus, Pseudogobio esocinus, Hemibarbus longirostris, Microphysogobio yaluensis, Cobitis lutheri, Iksookimia koreensis, Pseudobagrus fulvidraco, and Rhinogobius brunneus, remarkably decreased, and Z. platypus, Pseudorasbora parva, and Squalidus gracilis majimae increased.

• Korean Journal of Ichthyology
• /
• v.4 no.2
• /
• pp.55-62
• /
• 1992

Study on the fish fauna of the Chuam Dam in Sungju-gun, Chollanamdo, Korea was conducted from March 1990 to October 1990. Twenty-eight species belong to 23 genera and 11 families have been collected at five areas within the dam. The dominant species were Zacco platypus, Acheilognathus limbata and Zacco temmincki. Among the collected fishes, 5 species were known to be endemic species in Korea. They were Acheilognathus yamatsutae, Sarcocheilichthys variegatus wakiyae, Coreoleuciscus splendidus, Microthysogobio yaluenis, Cobitis longicorpus, Pseudobagrus koreanus, Liobagrus mediadiposalis and Odontobutis platycephala. The frequencies occurrence were 86.71% for 5.2% for Cyprinidae and Osmeridae.

• Korean Journal of Ichthyology
• /
• v.10 no.2
• /
• pp.184-190
• /
• 1998

The early life history of black bullhead, Pseudobagrus koreanus, endemic to Korea was investigated to get biological information needed in artificial production of seedlings and in recovering natural resources. The fertilized eggs showed some characteristics in having heavy sticky material and minute folds which is formed radical pattern on the egg membrane. The shape of egg was spherical and $2.59{\pm}0.08$(2.45~2.70, n=10)mm in diameter. The yolk had not oil globule. The first cleavage was observed 2 hrs after insemination at $21{\sim}23^{\circ}C$, and the progressive cleavage were done about 30 min. interval. The characteristic changing of the yolk surface started at morula stage and continued to the end of gastrula. Hatching was started 72 hrs and completed 90 hrs after fertilization. The size of the larvae were 5.41~5.81mm in total length and 2.76~2.94mm in preanal length, and the number of so mites was 15-16+33~34(48~50). The barbels and swimbladder were completed and all the fins except second dorsal were appeared 1 week after hatching. The larvae attained 9.67~10.52mm in total length and 5.20~5.65mm in preanal length. All the fin sets and color pattern were completed 2 weeks after hatching and body mucus was secreted at that stage. The juvenile attained 14.59~16.02mm in standard length, 3.31~4.16mm in head length and 8.07~9.31mm in prenal length.

• Korean Journal of Ichthyology
• /
• v.26 no.1
• /
• pp.50-69
• /
• 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
• /
• v.19 no.2
• /
• pp.112-119
• /
• 2007

A histological study on development and transformation of the oocyte' follicle cell for Korean four sillurid fishes, Liobagrus obesus, L. mediadiposalis, Pseudobagrus koreanus, and P. brevicorpus was performed by light and electron microscopes. The follicular layer surrounding the oocyte consisted of an outer theca cell and an inner follicle cell (granulosa cell). The follicle cells of the oocyte were flatten cells at early oocyte but during vitellogenesis they were transformed it to a single layer of cuboidal cell, then to a single columnar cell layer, and finally to a layer covered with a substance secreted by themselves. Although the development and transformation of the follicle cells was similar to four species, the secreted materials, called an adhesive membrane, were divided into two types in its appearance and nature. Firstly, a jelly coat-like type was found in L. obesus and L. mediadiposalis, which they are presumed to be polysaccharides and mucoproteins in its nature and secondly, a granular type in P. koreanus and P. brevicopus, being mucoprotein. A zona radiata with about $0.6{\sim}3.1{\mu}m$ thin was present below the adhesive material secreted by the transformed-follicle cell's activity. The zona radiata was composed of two layers, a thin externa and a thick interna.