• Applied Microscopy
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• v.44 no.1
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• pp.1-7
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• 2014

The spermatogenesis of Siamese fighting fish, Betta splendens, belongs to Osphronemidae was investigated by light and electron microscopic observations. In primary spermatocyte stage, the nucleus was comparatively large ellipsoidal, and mitochondria showed a marked development in cytoplasm. In secondary spermatocyte stage, the germ cells were smaller than that of primary spermatocytes. The nucleus was a spherical shape and intercellular space was formed between germ cells. In spermatid stage, the early spermatids were not much different from a secondary spermatocyte. But, the chromatin condensation was occurred from the outside to the inside. The nucleus was more condensed. Intracellular space was larger than early spermatid. The mitochondria were rearranged in a middle piece, and occupied about half of the head part in early sperm. In sperm stage, the head of mature sperm was a spherical shape and had no acrosome. The flagellum was showed the typical 9+2 array of microtubules. Also, the tail of sperm had no lateral fins and outer coarse fibers. These ultrastructural characteristics can be used in classification of species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.281-286
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• 2004

Spermatogenesis and sperm ultrastructure of the marsh clam (Corbicula japonica) were investigated by electron microscopic observations. Testis of the marsh clam consists of numerous spermatogenic follicle containing germ cells in the different developmental stages. Spermatogonia are located nearest the outer wall of the follicle, while spermtocytes and spermatids are positioned nearer to the lumen. Spematogonia are oval-shaped and about $5{\mu}m$ In diameter. Spermatogonia develop into spermatocyte, spermatid and spermatozoon. In the spermatid to about $2{\mu}m$ in diameter, cytoplasm decreases and mitochondria move to the base of the nucleus and fuse into several spheres, the centrioles become orthogonally oriented, a flagellum appears, and an acrosomal vesicle forms. The mature sperm has primitive type, consisting of a head, a midpiece and a tail. The sperm was arrow-shaped, and its head is about $8{\mu}m$ long and comprised of a long nucleus and an acrosome. The four mitochondria encircled the centrosome in midpiece. The flagellum had the classical 9+2 axoneme structure, and axonemal lateral fins in the tail were observed.

• Korean Journal of Ichthyology
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• v.34 no.2
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• pp.133-137
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• 2022

Two specimens of Apogon unicolor (81.0 mm and 96.3 mm in standard length) belonging to the family Apogonidae were firstly collected by using a gill net from the southwestern coastal waters of Jejudo Island, Korea in July 2013. These species are characterized by having 26 lateral line pores, a first dorsal fin with 6 spines, 2+1+8=11 developed gill rackers, posterior margin of preopercle serrated, without markings and spots on the body. Our specimens are well-matched in their morphological and molecular characteristics with Apogon unicolor previously reported. Thus, we newly add this species to the Korean fish fauna and propose its new Korean name "Jin-hong-eol-ge-bi-neul" because the overall fish body and fins reveal deep red colors.

• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.137-145
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• 2000

The embryonic and larval development of Chelon lauvergnii (Eydoux & Souleyet) was surveyed by incubating artificially inseminated eggs with parent fishes obtained at Kang-wha island in the mid-western coastal area of Korea on June, 1997. The fertilized eggs were transparent, spherical in shape, measuring 0.95~1.08 mm in diameter, having a large oil globule, and their perivitelline space narrow, and began to hatch at 40 hrs. in water temperature $22{\pm}1^{\circ}C$. The newly hatched larvae were 2.35~2.68 mm in total length with 23 myomeres, anus opened, mouth closed, preanal length 58.7~61.6% of total length, oil globule located in posterior end of yolk sac. Melanophores, branch in shape, were distributed mainly along the ventro-lateral region of trunk part and a few on the anterior end of caudal part and surface of oil globule. The larvae measuring 3.08~3.36 mm in total length absorbed yolk material completely in 3 days after hatching, in which air bladder began to appear and mouth opened. In 8 days after hatching, the larva was measured 5.09 mm in total length, its posterior end of notochord began to flex upward and the caudal fin rays differentiated as 7, finfold of the second dorsal and anal fins appeared. In this time, melanophores, branch in shape, were concentrated in the anterior half region of the caudal part and a few also distributed on the top of head, snout region, ventral margin of lower jaw and isthmus region. In 12 days after hatching, the larva measuring 8.48 mm in total length completed all the fins (D. IV-9; P1. 16; P2. I, 5; A. II, 9) and reached to the juvenile stage. Melanophores, in this time, were distributed on the mid-lateral region of the caudal part in enlargment than before and a few also found in the dorso-lateral region of the trunk part, and in the cheek region.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.225-233
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• 1975

Morphological changes of early post-larval and young stages of Chasmichthys dolichognathus HILGEnDORF (Family Gobiidae) have been studied based on the samples of 953 individuals collected in June 1968, July 1969 and July 1971. Particular emphasis was paid on the development of fin rays, chromatophore patterns and ventral fins. The primordial fin rays of the first dorsal fin appear in the post-larvae of around 8.0 mm in total length, and dorsal fin fully develops in the larvae of around 9.2 mm. In the early young stages of 17.0 mm in total length fin rays have completely developed. According to chromatophore patterns the larvae are grouped into three successive groups. The larvae at the early stages of 6.3-14.2 mm have melanophores on the whole dorsal surface, the posterior ventro-lateral part of the tail and the basal part of the caudal fin. In the later larval stages of 17.0-24.4 mm a group of melanophores are added on medio-lateral part of the tail. These melanophores extend anteriorly and eventually cover the medio-lateral part of the whole body. In the early young stages of 97.2-34.8 mm the chromatophores cover the whole body surface in cloudy and H-shaped patterns. The chromatophore patterns of this stage are distinctive as generic characters of the fish. Fin membranes of the ventral fin appear in the post-larval stage (ca. 7.4 mm), and the primordial fin rays develop in the late post-larval stages (ca. 14.2 mm). The fin rays develop into a complete sucker in the young fish stage of around 30.0 mm in total length.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.153-158
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• 2014

A natural intergeneric hybrid between Rhodeus pseudosericeus and Acheilognathus signifer was collected in their sympatric area, the Jucheongang (stream), the Namhangang (river), Korea. Morphological characters as well as mitochondrial cytochrome b (mt-cyb) gene were investigated to confirm the natural hybrid origin. In the comparison of morphological characters, the natural hybrid appeared to have intermediate characters between two parental species in several key characters such as the band of dorsal fins, the color pattern of body, and the body spot and stripe. Also, the collected specimen had an incomplete lateral line with a large number of pored scales. In analysis of mt-cyb gene, it revealed that the maternal species of the natural hybrid appeared to be R. pseudosericeus due to their 100% sequence identity. Thus, such results gave convincing evidence for the occurrence of a natural intergeneric hybrid between Rhodeus pseudosericeus and Acheilognathus signifer.

• Korean Journal of Ichthyology
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• v.11 no.1
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• pp.1-11
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• 1999

The five species of the genus Microphysogobio in Korea are reviewed with the keys to species and their illustrations: M. longidorsalis, M. jeoni sp. nov., M. koreeneis, M. yaluensis, and M. rapidus. Microphysogobio tungtingensis uchidai was treated as a junior synonym of M. yaluensis based on having the distinct papillae of upper lip and the color pattern on body sides by the examination of the type specimens. Microphysogobio jeoni is described as a new species from the specimens collected in the Naktong River, Han River and Keum River, Korea. it is well distinguished from the related species by the slender body, undeveloped papillae of upper lip and unspotted fins. Microphysogobio yaluensis was showed the clinal variations in the number of lateral line scales and vertebrae among the populations in the western drainages of Korea. It is remarked biogeographically that the five species of Microphysogobio are all endemics to Korea with the restricted ranges.

• Korean Journal of Ichthyology
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• v.7 no.2
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• pp.114-119
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• 1995

A flathead fish, collected from the water off Cheju lsland is tentatively identified as Inegocia guttata of the family Platycephalidae for the first time from Korea. Inegocia guttata is similar to Cymbacephalus beauforti in morphological characters, but differs from C. beauforti in lacking dermal flaps on eyes and having pored scales much fewer than oblique scales slanting backward and downward above the lateral line, single and tongue - like interopecular flap, nasal spines and circled blackish spots in the pectoral and ventral fins. A new Korean name, "Akoyangtae", is proposed for the I. guttata.

• Korean Journal of Ichthyology
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• v.10 no.2
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• pp.260-267
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• 1998

Three species of the order Perciformes collected from coastal waters of Cheju Island, Korea were documented with photographs, all of which are newly known to Korea. Nemipterus bathybius Snyder, 1911 of the family Nemipteridae is distinguished by seven anal soft rays and the most upper ray at the caudal fin elongated. Cirrhitichthys aureus (Temminck et Schlegel, 1842) of the family Cirrhitidae (New Korean name: Hwangbokdom-kwa), is characterized by the five to six light black spots on the dorso-Iateral sides, 12 dorsal soft rays and a dorsal fin without spots and bands. Parapercis aurantiaca D$\ddot{o}$erlein, 1884 of the family Pinguipedidae, has several taxonomic characters. The dorsal spines and the soft rays of the dorsal fins were connected without a notch. The five to six dark yellow bands with the same size of eye length were shown on the lateral region. A new Korean name Kinsilkkoridom is proposed for the Nemipterus bathybius, and Cirrhitichthys aureus, Hwangbukdom, and Parapercis aurantiaca, Hwangssangdonggari.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1573-1580
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• 2016

The disease occurred in cultured eel (Anguilla japonica) in a recirculatory culture system without any separated filtration apparatus. As the pond had a high level of nitrite with $60mg/{\ell}$, 1% NaCl was added to reduce nitrite toxicity to eel. The first outbreak was observed a week after the NaCl treatment and continued for 10 days. Accumulated mortality was about 0.2-0.5%. Affected fish ranged from 150-350 g were usually anorexic and exhibited yellow colour in the skin of the abdominal region and at the base of pectoral fins, as well as in the eyes. In a few individuals with severe symptoms, the lateral skin was also yellowish. The spleen, kidney, muscle and gall bladder were yellowish and the liver was pale-yellow colour but green on the posterior part. The gall bladder was shrunken without bile. Some abnormal erythrocytes such as "tear drop" cells (dacrocyte) were observed in peripheral blood smears stained with May-Grunwald Giemsa. Hematocrit values and hemoglobin contents in the jaundiced eel were significantly lower compared with apparently heathy eel. Severe haemosiderosis accompanied by erythrophagocytosis was found in the kidney and spleen. Haemosiderin deposits were observed in macrophages of the haematopoietic tissue of the kidney and in the splenocytes. But no significant alterations were found in the hepatic cells. In this study we report the first outbreak of jaundice in cultured eel in Korea. Pathological and hematological investigations suggested that severe hemolysis may resulted in jaundice in eel although the cause of hemolytic jaundice was not identified in this study.