• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.549-557
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• 2023

This study aimed to investigate taxonomic differences in the early life history characteristics of Rhodeus ocellatus and Rhodeus notatus through an interspecific hybridization experiment. The hatching rates of the cross-bred eggs were 50% for the ON cross (R. ocellatus ♀×R. notatus♂) and 67% for the NO cross (R. notatus♀×R. ocellatus♂). Interestingly, the hatching time of the hybrids was longer than that of their parents. The newly hatched larvae exhibited distinct differences in their physical characteristics. The head of the adult fish protruded forward more than that of the ON cross. The pterygoid process was 45° for the ON cross and 90° for the NO cross. Furthermore, the tail shape of the ON and NO crosses closely resembled that of R. notatus.

• Korean Journal of Ecology and Environment
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• v.53 no.3
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• pp.275-285
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• 2020

Two specimens presumed to be hybrids of Rhodeus pseudosericeus and R. notatus were collected from the Sangcheon Stream of the Han River, Korea. The body color of natural hybrid individuals was yellowish brown, showing the intermediate characteristics of R. pseudosericeus and R. notatus, but overall, the characteristics of R. notatus were similar. Meristic and morphometric characters, the number of dorsal fin rays, anal fin rays and longitudinal row scales showed a hybrid index (HI) of 0, indicating the characters of R. notatus. The hybrid index of predorsal length (HI=74.6), preanal length (HI=75.3), and preventral length (HI=77.6) were similar to the characters of the R. pseudosericeus. Also four characters were appeared to have intermediate characters between R. pseudosericeus and R. notatus; number of gill rakers (HI=55.3), body depth (HI=67.9), snout length (HI=43.4), and inter orbital width (HI=44.8). The rest of 14 characters deviated between 0 and 100, showing unique characteristics of hybrid individuals. Recombination activating gene 1 (RAG1) analysis, hybrids were identified as natural hybrids due to the overlapping peaks of their parent species. Also, as a result of analysis using the cytochrome b gene (COB), one individual was derived from R. pseudosericeus, while the other was derived from R. notatus.

• Korean Journal of Ichthyology
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• v.33 no.3
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• pp.157-166
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• 2021

Three specimens, presumed to be natural hybrids between Rhodeus notatus and R. ocellatus, were collected from Onyangcheon Stream area, Jwabu-dong, Asan-si, Chungcheongnamdo, the Republic of Korea, and morphological and phylogenetic analyses were performed to clearly identify their parent species. The body color of the three natural hybrids was light greenish-brown on dorsal side, and the size of red area on the upper front of the dorsal fin and the outer margin of the anal fin generally showed intermediate characters between the parent species, R. notatus and R. ocellatus. Among the measurement and meristic characters, the ratio of prepectoral length and preanal length in the standard length, and the ratio of snout length, interorbital width, length of caudal peduncle and depth of caudal peduncle in the head length, and the number of longitudinal row scales were analyzed as the unique characters of natural hybrids. In the rag1 gene of nuclear DNA, the three natural hybrids were analyzed to be reflected all the single nucleotide polymorphism sites between R. notatus and R. ocellatus, and in the phylogenetic tree using the cytb gene of mitochondrial DNA, they formed the same genetic clade as R. notatus. Therefore, three specimens, presumed to be natural hybrids analyzed in this study were identified as interspecific hybrids between female R. notatus and male R. ocellatus.

• Korean Journal of Ichthyology
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• v.18 no.4
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• pp.339-346
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• 2006

In this study we conducted artificial hybridization between two sibling species, Rhodeus uyekii and R. notatus, and observed the morphological characteristics in early developmental stage. The two species showed difference in egg shape having rhombus and club respectively. The morphology of yolk of larva just hatched also showed well specific characteristics, that is the bean chaff type for R. uyekii (U type) and anchor type for R. notatus (N type). The rate of fertilization between female R. uyekii and male R. notatus (UN type) and between female R. notatus and male R. uyekii (NU type) were complete and its hatching rate were very high, 71.6% for UN type and 97.5% for NU type. The differences occurred in the yolk shape of hatched larvae for each combination of hybrids. In the group of UN, U type of larvae were found very rarely, but almost all the larvae showed intermediate shape polarized to NN type. Similar phenomenon was observed in the NU having intermediate polarized to UU, but without any NN type. These hybrids will be analyzed for their external morphology, sex ratio, the function of sexual organ and karyology after they grown up to adult.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.151-159
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• 2012

Cross and reciprocal hybrids from intrageneric crosses between Rhodeus uyekii and R. notatus were analyzed morphometrically using truss and classical dimensions, erythrocyte size using blood smears, and cytogenetically using flowcytometry, then compared with the parental species. Although the morphometric assessment based on body proportions indicated that the hybrids were generally intermediate between the maternal and paternal species, the morphometric characters of cross and reciprocal hybrids included at least 14 paternal-like and 7 maternal-like, and 13 paternal-like and 5 maternal-like characters, respectively (P<0.05). The pigmentation of the hybrids was intermediate in some respects, and resembled that of the parental species. The DNA content of the cross and reciprocal hybrids, based on flow cytometry analysis, was significantly different from the parental species. The characterization of morphometric traits and the cytogenetic analysis of hybrids of R. uyekii and R. notatus used in this study may be useful for distinguishing genotypes in commercial Acheilognathinae aquaculture.

• Journal of Aquaculture
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• v.22 no.1
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• pp.79-82
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• 2009

Reciprocal interspecific hybrids between two bitterling species Rhodeus uyekii (RU) and R. notatus (RN) were genetically identified based on the partial sequence analysis of recombination activating gene-1 (RAG-1) gene. Out of 863 bp positions analyzed, 13 nucleotide substitutions were detected between the two parental species (RU and RN genotypes). Both the induced hybrids (RU female$\times$RN male; UN genotype) and their reciprocal counterparts (RN female$\times$RU male; NU genotype) displayed the double peaks (or polymorphism) of sequence chromatograms at the 13 diagnostic positions, indicating that those hybrids were actual karyogamy derived from the two parental haploid genomes. However, it was not possible to distinguish between the reciprocal interspecific hybrids.

• Korean Journal of Ichthyology
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• v.25 no.2
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• pp.53-58
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• 2013

Seven individuals (16.1~29.1 mm in length) which were estimated with fishes of genus Abudefduf were collected in Seogwipo, Jeju Island in the summer of 2011 and 2012. Among them, five individuals (20.8~29.1 mm SL) are similar to Abudefduf notatus, based on morphological characters such as yellow transverse band on the body, one small black spot on the base of the pectoral fin, and yellow caudal fin. On the other hand, two individuals (16.1 mm, 17.0 mm SL) differ from them in several light transverse bands and transparent rays of all fins except for pelvic fin, and anterior transparent head with only one (16.1 mm). According to the results of molecular analyses of 578 base pairs of mtDNA 16S rRNA sequences, these individuals correspond to A. notatus adult, with a high bootstrap value of 95% (genetic distance, d=0.002). Therefore, this study shows that the individuals more than 20.8 mm similar to adult body color but the 16.1 mm individual differs to that of adult. We confirm that this species changes to body color during their early life stages. This result regards as a survival strategy to protect themselves against their predator during their early life stages.

• Korean Journal of Environment and Ecology
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• v.37 no.2
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• pp.151-162
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• 2023

This study investigated the characteristics of fish communities and inhabiting status of the endangered species, Rhodeus pseudosericeus, in the Geumdang Stream in Korea from March to October 2021. A total of 1,698 fish in 5 families and 25 species were collected from 7 survey stations during the survey period. The dominant species was Zacco platypus (relative abundance, 46.5%), and the subdominant species was Squalidus gracilis majimae (16.7%), followed by Rhynchocypris oxycephalus (12.0%), Z. koreanus (5.7%), Pungtungia herzi (3.2%), R. pseudosericeus (2.0%), R. notatus (1.9%), and Acheilognathus rhombeus (1.8%). Nine Korean endemic species (36.0%) were collected, including R. pseudosericeus, R. uyekii, Sarcocheilichthys variegatus wakiyae, Microphysogobio yaluensis, S. gracilis majimae, Z. koreanus, Cobitis nalbanti, Iksookimia koreensis, and Odontobutis interrupta. An exotic species, Micropterus salmoides, designated as an invasive alien species (IAS), was collected downstream. The investigation of the habitat patterns of the endangered species (class II), Rhodeus pseudosericeus, showed a habitat range of about 6 to 7 km in the middle of Geumdang Stream (RP-1 to RP-4), and this species inhabited the edge with water depths of 0.3 through 1.0 m with slow water flow and many aquatic plants. According to the community analysis results, the overall dominance and evenness indexes were low, while diversity and richness indexes were high, and the cluster structure was largely divided into upstream and middle-downstream areas. The river health (fish assessment index) evaluated using fish was assessed as good (3 stations), normal (3 stations), and bad (1 station), and water quality was evaluated as good both upstream and downstream. Compared to previous studies, the number of species was relatively similar, and among the species that appeared in the past, 13 species did not appear in this survey, while 6 species appeared for the first time in this survey. Disturbance factors included river construction, many weirs, and the appearance of the ecosystem-disturbing species, M. salmoides. Since Geumdang Strem has high conservation value because it is home to many species in the Acheilognathinae subfamily, including the endangered species R. pseudosericeus, continuous attention and systematic conservation measures are required.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.3
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• pp.131-138
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• 1988

Collection of organisms for the fisheries resources community were obtained with a set net during 8 months between May, 1985 and May, 1986 on the coast of Pukchon, Cheju Island, Korea. Most of organisms, representing 36 species, were less than 20cm $(93\%)$ in length, and 130g $(91\%)$ in weight. The four most abundant species were jack mackerel, Trachurus japonicus ; squid, Todarodes pacificus : damsel fish, Chromis notatus : and rabbit fish, Siganus fuscescens, which comprised about $83\% in number and about $73\%$ of the total catch. The diversity index of the number of species and information indices for individual and catch were the highest in October and the lowest in Septemer, indicating a close relationship with the change between the species number and catch at that time. A cluster analysis of 17 species was illustrated from the similarity matrix. All of the 17 species were grouped at the 0.2 similarity level. Three groups were present at 0.60 level, whereas species in other groups were sporadic in occurrence.