• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.103-110
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• 1983

The main purpose of the present study is to evaluate a revolving plate type biofilter system for mass culture of eel(Anguilla japonica) based on the experimental rearing for 120 days (Oct. 1982-Feb. 1983). Water quality changes, growth efficiency of fish and fish disease treatment were critically evaluated. A revolving plate type biofilter system was designed(Fig. 1). The system consisted of a glass tank (150 l), a revolving plate biofilter and a settling tank(150 l). The biofilter consisted of 60 submerged quadriangular plates ($28{\times}37$ cm) and 30 revolving plates (32 cm diameter) for a total of 19.0 $m^2$ of surface area. The revolving plates were made to rotate 10 time per minute, The total water volume of the rearing system were 300 l, and everyday 1/3 of the total water volume were changed with freshly prepared water. In the rearing system a total of 2 kg of eel (1,500 individuals, mean weight:1.3 g) were reared fed on the pellet feed and the dough feed. The growth efficiency were much better for the pellet feed (FC: 1.79) compared to the dough feed (FC: 3.56). During the experimental rearing water quality control was satisfactory. Total ammonia concentrations were 0.38-0.59 ppm and nitrite concentration were 0.83-1.19 ppm. On the other hand alkalinity decreased from 176ppm just after the water change to 17ppm just before the water change. The low alkaline condition was compensated by the regular change of water. Epidemics of parasitic gill-flocks (Pseudodactvlogylus sp.) was observed, and they were easily eliminated by the treatment of DDVP (1.0 ppm). Trichodina sp. and Costia sp. were observed, and they were also controlled by the treatment of potassium permanganate (4.0 ppm).

• Applied Microscopy
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• v.28 no.4
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• pp.447-463
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• 1998

This study was carried out to investigate the histomorphological changes and the electrophoretic patterns of egg components, obtained from 100 of 2-year-old female catfishes (Silurus asotus). Female Korean catfishes collected in the vicinity of Chollabukdo have synchronous ovaries which discontinously ovulate eggs during the breeding season (from late May until early July). The fishes were killed by severing the spinal cord just posterior to the head after immobilization with tricaine methanesulfonate (MS 222). Especially, the light microscopic and ultrastructural changes of ooplasm and follicular membranes of oocytes, were examined by means of light and transmission electron microscopy. The size of the nucleoli and number of the yolk granules increased as the oocyte groved. Yolk granules were deposited in the oocyte as fluid Due to tile presence of large early and late maturing oocytes, their ovaries were enlarged, transparent, granular and greenish in color. As the percentages of fish in late maturing oocyte (LMO) and ripe oocyte (RO) stage increased from March to April, mean gonadosomatic index (GSI) values (19.95%) increased. Zona radiata changed from squamous into cuboid in shape in the early maturing oocyte (EMO) stage. Processes, microvilli, from the zona radiata and from the oocyte grow, and make contact with each other in the pore canals of the zona radiata during vitellogenesis, but are withdrawn as the zona radials becomes more compact and devoid of pore canals during oocyte maturation. Seasonal changes in the microscopic appearance of the ovaries were well correlated with those in both gonadosomatic index and macroscopic appearance. The main cytological changes such as increase in size of cell, nucleus, nucleolus, and increase in number of nucleoli and mitochondria demonstrated with electron microscopy in the previtellogenic oocytes of Korean catfish, provided evidences for important synthetic processes in an early preparatory phase of oocyte development. The electrophoretic pattern of major band in mature stage was much thicker (24 k, 66 k, 90-110k dalton) than that in previtellogenic phase.

• Fisheries and Aquatic Sciences
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• v.24 no.11
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• pp.383-389
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• 2021

On the southern coast of South Korea, dark-banded rockfish, sea bass, and red seabream are caught by single-line fishing. In particular, red seabream and sea bass are caught in the Jeollanam-do region using gear with attached fishing hooks, such as longline and single-line gear, with live shrimp as bait. The objective of this study was to compare the catch efficiency of two types of live shrimp (naturally grown Shiba shrimp [Metapenaeus joyneri] and cultured whiteleg shrimp [Litopenaeus vannamei]) used as bait. The investigation included interviews, on-board surveys, and water tank experiments. Interviews were conducted with relevant parties to determine the preference for live shrimp as bait, and the results showed a greater preference for cultured whiteleg shrimp. Further, an on-board survey was conducted to compare catch efficiency between these two types of live shrimp bait for single-line fishing. The on-board investigations were conducted once or twice a month between June and October. In total, the amounts of fish caught using naturally grown Shiba shrimp and cultured whiteleg shrimp were 56 and 52, respectively. Of these, the numbers of sea bass, the primary target fish species, caught using naturally grown Shiba shrimp and cultured whiteleg shrimp were 43 and 40, respectively. Thus, the results showed that there was almost no difference in the number of fish caught based on the bait used. However, according to a water tank experiment, cultured whiteleg shrimp survived longer than naturally grown Shiba shrimp.

• Journal of fish pathology
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• v.35 no.2
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• pp.215-223
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• 2022

Disease including parasite, bacteria and virus cause serious mortality to salmonid fish in the aquaculture. In this study, we investigated the current disease status of the rainbow trout (Oncorhynchus mykiss) and coho salmon (Oncorhynchus kisutch) in Yanayang, Pyeongchang, Jeongseon and Yeongwol of Gangwon province in 2021 and performed molecular characterization of those pathogen. For parasites, Ichthyophthirius multifiliis was observed at 2 farms. For bacteria, we identified Aeromonas sobria from kidney of rainbow trout using phylogenetic analysis of gyrB gene. A. salmonicida were isolated from necrosis site of gill cover and fin in coho salmon and necrotic lesion of fin in rainbow trout. Phylogenetic analysis using vap gene indicated that A. salmonicida isolated in this study were clustered with previously reported A. salmonicida subsp. salmonicida isolates. For virus, JRt-Nagano type of infectious haematopoietic necrosis virus was detected in rainbow trout, but infectious pancreatic necrosis virus and Oncorhynchus masou virus were not detected. These results provide useful information for the prevention of disease spread and transmission when cultivating new species such as Atlantic salmon in Korea.

• Fisheries and Aquatic Sciences
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• v.25 no.11
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• pp.559-571
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• 2022

Galectins, a family of ß-galactoside-binding lectins, have emerged as soluble mediators in infected cells and pattern recognition receptors (PRRs) responsible for evoking and regulating innate immunity. The present study aimed to evaluate the role of galectin-1 in the host immune response of redlip mullet (Liza haematocheilia). We established a cDNA database for redlip mullet, and the cDNA sequence of galectin-1 (LhGal-1) was characterized. In silico analysis was performed, and the spatial and temporal expression patterns in gills and blood in response to lipopolysaccharide polyinosinic:polycytidylic acid, and Lactococcus garvieae were estimated via quantitative real-time PCR. Functional assays were conducted using recombinant protein to investigate carbohydrate binding, bacterial binding, and bacterial agglutination activity. LhGal-1 was composed of 135 amino acids. Conserved motifs (H-NPR, -N- and -W-E-R) within the carbohydrate recognition domain were found in LhGal-1. The tissue distribution revealed that the healthy stomach expressed high levels of LhGal-1. The temporal monitoring of LhGal-1 mRNA expression in the gill and blood showed its significant upregulation in response to immune challenges with different stimulants. rLhGal-1 exhibited binding activity in response to carbohydrates and bacteria. Moreover, the agglutination of rLhGal-1 against Escherichia coli was observed. Collectively, our findings suggest that LhGal-1 may function as a PRR in redlip mullet. Furthermore, LhGal-1 can be considered a significant gene to play a protective role in redlip mullet immune system.

• Korean Journal of Ichthyology
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• v.21 no.3
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• pp.167-176
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• 2009

Species composition and seasonal variation of fish assemblages in the western coastal waters of Jeju Island were determined using samples collected by a trammel net, gill net and fish pot in 2008. During the survey period, a total of 81 species (45 families and 13 orders) of fishes were identified, and Perciformes and Scorpaeniformes accounted for 69.1% of the total number. The number of species was higher in warm months than in cold months, showing a peak in July at 54 species and a low in April at 42 species. The number of individuals and the biomass peaked in September at 895 inds. and 135 kg, and were lowest in December at 450 inds. and 52 kg. The diversity indices of fish catches in trammel net and fish pot were 2.88~3.22 and 1.31~1.87, respectively, and were highest in September. Sebastiscus marmoratus, Stephanolepis cirrhifer, Choerodon azurio and Pseudolabrus sieboldi were dominant species, which occurred abundantly during the entire survey period.

• Journal of Life Science
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• v.28 no.9
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• pp.1118-1126
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• 2018

In this study, investigated the general characteristics and diagnostic methods types of streptococcosis among various fish disease pathogens that caused a lot of economic damaged to aquaculture fish based on the previous research paper. Streptococcosis infection of fish is considered a reemerging disease affecting a variety of wild and cultured fish throughout the world. Calssifiacation of Gram positive cocci based on DNA-DNA hybridization coupled with 16S sequencing has shown that at least five different species are considered of significance as fish pathogens: Lactococcus garvieae, L. piscium, Streptococcus iniae, S. agalactiae, S. paruberis, Vagococcus salmoninarum. Symptoms of infection with streptococcosis disease such as body color change, eyeball abnormality, gill discoloration, bleeding, abdominal distension, swelling of the kidney and spleen. In addition, it usually occurs from June to October when the water temperature rise a lot of fish death. Currently, 16S rRNA, 16S-23S rRNA intergenic spacer region (ISR), Random Amplified polymorphic DNA (RAPD), Ribotyion (RT), Loop-mediated isothermal amplification (LAMP) are among the methods for diagnosing streptococcosis. Among them, the LAMP method, which is high applicable to the aquaculture farm has attracted the spotlight, but due to problems such as confirmation of results. This seems to minimize the economic loss of streptococcosis which complements the problem so that it can be easily used from the diagnosis to the results confirmation.

• Journal of fish pathology
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• v.7 no.2
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• pp.151-160
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• 1994

In order to elucidate the patterns of tissue damage evoked by the scuticociliatids, eighteen fingerlings of Japanese flounder, Paralichthys olivaceus, heavily infected with an unidentified scuticociliatid were histopathologically examined. Skin layer with the underlying musculature were severely necrotized due to the infestation of the ciliates. However in the early lesions, both dermis and myofibres remained relatively intact compared with other surrounding loose connective tissues. Mild damages were found in more dense tissues. One or more scuticociliatids were recognized in the blood and lymph vessels of the loose connective tissues with or without destructive changes. Many of nerve trunks or ganglia were also parasitized with less marked histological damage in the parenchyma. Dura and its adjacent tissues in the spinal cord were severely necrotized with massive accumulation of the ciliates in subdural space. The parasitic invasion in the central nervous system was usually confined to the cortical region. In the gill, variable degenerative changes were occurred due to the invasion of the ciliates recognized in the blood vessels of branchial arches or primary filaments. From these results, it was strongly suggested that the scuticociliatids are very actively penetrated into the deep tissues mainly through the severe destruction of the loose connective tissue components and that the vascular system could play a role in the rapid distribution of the ciliates to the remote tissues or organs.

• Journal of Aquaculture
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• v.9 no.4
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• pp.395-407
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• 1996

A feeding experiment for 160 days was conducted to evaluate effects of dietary soybean meal (SBM) on the apparent digestibility, ammonia excretion and body composition of rainbow trout (Oncorhynchus mykiss). Seven diets containing $0\~70\%$ SBM were formulated based on iso-nitrogenous and iso-caloric basis of $44\%$ crude protein and approximately 4,200 Kcal/kg of gross energy. To evaluate the nutritional utilization of the SBM diets at the end of 60 and 120-day rearing with test diets, digestion rates of protein and lipid of SBM diets were measured. Fish fed the diets containing above $46\%$ SBM showed higher apparent digestibility for protein, but lower for lipid than did fish fed the control diet in both trials. Protein and fat contents in the carcass were similar for all experimental fish, except for fish fed $58\%$ and $70\%$ SBM which showed lower fat content than the others, but composition of fatty acid and amino acids were not affected by dietary SBM levels. Gill and urinary post-prandial ammonia ($NH_3-N$) excretions were measured at 12 and 24 hours after single feeding of the experimental diets. Excretions of $NH_3-N$ measured after 24 hours were almost 1 times higher than those measured after 12 hours. Total excretion fer the 24 hours by fish fed $70\%$ SBM was $15\%$ higher than that of fish fed the control diet. Results of present study may suggest that the rainbow trout which were fed above $34%\;or\;46\%$ of SBM diet showed a decrease gradually in lipid bioavailability compared to the control group.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.3
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• pp.218-223
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• 2006

The present study evaluated effect of egg yolk immunoglobulin (IgY) from the hen immunized with Edwardsiella tarda. The purification of anti-E. tarda IgY was performed by polyethylene glycol (PEG). Purified IgY had heavy chain of 64 kDa and light chain of 27 kDa size. The IgY was instable against olive flounders digestive factors and artificially modulated pH 2 and 3. Nevertheless, some activity of IgY appeared in intestine. IgY was orally administered with viable E. tarda to the olive flounders and the efficacy of protection against E. tarda infection was evaluated. Orally administered IgY at a dose of 20 mg/fish delayed infection period of E. tarda cannulated at $10^{6{\sim}8}CFU/fish$ to small size (30~40 g) and middle size (110~120 g) flounder. Moreover, orally administered IgY at dose of 20 mg/fish inhibited the penetration of E. tarda cannulated at $10^8CFU/fish$ into the liver, kidney, spleen and gill via intestine. The fish orally administered with IgY showed increased survival rate. These results suggest that egg yolk containing anti-E. tarda IgY is effective in preventing edwardsiellosis.