• Asian-Australasian Journal of Animal Sciences
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• v.18 no.11
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• pp.1513-1518
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• 2005

The work reported here is an attempt to explore the possibility of DNA microsatellite loci transfer (cross-species amplification) to other economically important aquacultured catfish species other than its source species. A total of 25 new microsatellite loci developed for riverine catfish, Mystus nemurus were successfully cross-amplified in two distantly related catfish species within the suborder Siluroidei. Five out of the 19 loci that successfully cross-amplified in Pangasius micronemus were polymorphic, while for Clarias batrachus, cross-amplification was successful using 17 polymorphic loci. The observed heterozygosities were high for all the three catfishes. The results indicated that microsatellite loci could be as polymorphic in non-source species as in the source species.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.42-42
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• 2003

The far eastern catfish (Silurus asotus) growth hormone (GH) gene was cloned and characterized. The complete nucleotide sequences of genomic GH gene sequences as well as a catfish GH cDNA were obtained by RT-PCR and gene filter screening. The GH cDNA and genomic gene span 1.0 and 1.8 kb from the start codon to the polyadenylation signal, respectively. Both on cDNA and gDNA GH genes, the sequence polymorphism was detected including various silence mutations. The genomic GH gene comprised of only four exons and three introns, which was novel type of fish GH gene structure. The evolutionary relation of the catfish GH gene was inferred based on the comparative phylogenic analysis using the gene structures and sequences.

• Korean Journal of Veterinary Service
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• v.35 no.4
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• pp.347-350
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• 2012

L-theanine was examined for its effects on the generation of superoxide anion, lysozyme and anti-protease in the plasma of catfish (Silurus asotus) by a single intraperitoneal injection with five different concentrations (0, 3, 6, 9 and 12 mg/kg). When compared with the mock-injected group (0 mg/kg), both groups injected with 6 and 9 mg/kg were significantly enhanced in levels of superoxide anion in leukocytes, lysozyme and anti-protease in plasma. Based on the results, L-theanine is thought to function as an immunostimulant and/or immunomodulator on non-specific immune responses in catfish.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.7
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• pp.924-930
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• 2010

Ileal and total tract digestibility and nitrogen (N) balance of diets with four different protein sources were determined in growing pigs. The diets were based on rice bran, broken rice and maize meal and contained Tra catfish by-product (CBP), processed using three different methods, and marine fish meal (FM). The CBP diets consisted of the by-product in meal form, ensiled with molasses, and CBP waste water (WWBD). The four diets were fed to four growing pigs fitted with post-valve T-cecum (PVTC) cannulas in a $4{\times}4$ Latin Square design. All experimental diets included $Cr_2O_3$ at 5 g/kg feed as an indigestible marker. The ileal apparent digestibility of organic matter and ether extract was higher on diet WWBD than on the other three diets (p<0.05), and the total tract apparent digestibility was higher on diet WWBD than on the FM diet (p<0.05). The ileal and total tract apparent digestibility of crude protein and amino acids was not significantly different among diets (p>0.05). No significant effects of diet were found on N-retention and N utilization. In conclusion, the catfish by-product meal, ensiled catfish by-product and processing waste water diets and the fish meal diet had similar ileal and total tract apparent digestibility, and similar N utilization in growing pigs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.4
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• pp.338-343
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• 2006

Histological observations of the barbels of torrent catfish (Amblycipitidae) in Korea are reported. The bullhead torrent catfish (Liobagrus andersoni) and Korean torrent catfish (L. obesus) have eight obvious barbels in two pairs each on the maxilla and mandible. Each barbel is composed of an epidermis, dermis, and central cartilagerod. The epidermis of the maxillary and mandibular barbels of the bullhead torrent catfish is thicker than that of the Korean torrent catfish (P<0.05) and is formed of stratified epithelium that contains many cutaneous taste buds and a few small club cells. There are many taste buds on the upper part of each barbel. The dermis consists of loose connective tissue fibers that enclose blood vessels and bundles of nerve fibers. The barbels of these fish can be categorized into stiff and flexible types and are accessory, feeding, and sensory structures. Our results validate the barbels as gustatory receptor organs for these fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.23-26
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• 2006

Effects of sera from several fish species and insulin on the development of cultured Silurus asotus hepatocytes were investigated. Hepatocytes with high viability (95%) were obtained from the livers of male catfish by two step collagenase perfusion. Isolated hepatocytes, initially showed a typical round-shape, firmly attached to the culture dish within 24 h. In the presence of catfish serum, hepatocytes attached each other, spread well on the dish and developed into monolayer after 3-4 days of incubation. Cells within the established monolayer became polygonal in shape and their nuclei and boundaries being clearly visible under the microscope. In contrast, when incubated in FBS-supplemented or serum-free medium, cells managed to form small clusters, each made of 2-10 cells. Cells in FBS-supplemented medium further developed into larger clusters. However, these clusters failed to develope into monolayer. In addition, when insulin was deprived from culture medium, formation of monolayer also failed. From these data, it can be concluded that the presence of both catfish serum and insulin is necessary for the formation of monolayer of catfish hepatocytes and the functional role of fish serum may differ from that of insulin and can not be displaced by FBS-supplementation.

• Korean Journal of Veterinary Research
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• v.50 no.4
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• pp.331-333
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• 2010

Moribund albino catfish, Clarias sp., displayed from an indoor private commercial aquarium were submitted in the laboratory for diagnostic examination. Dense culture of bacteria was recovered from the kidney and was characterized using Vitek System 2 and showed 98% probability to Aeromonas (A.) hydrophila. PCR result showed positive using A. hydrophila extracellular hemolysin gene ahh1 (130 bp) and aerolysin gene aerA (309 bp). The 16S rRNA gene was identical and exhibited 97% sequence similarity with the other known isolates of A. hydrophila available in the GenBank. In this paper, we reported the isolation and molecular detection of A. hydrophila from an albino catfish.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.2
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• pp.148-156
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• 2010

This study was conducted to collect the information on the behavioral characteristics and the habitat environment of mandarin fish (Siniperca schezeri) and catfish (Parasilurus asitus) with acoustic telemetry method in Chungju Lake, Korea. Mandarin fish tended to stay within 1km from the release points in downstream, and had a strong diurnal behavior. They approached to the lakefront at night. They also preferred to stay at deep water off the lakefront. The average swimming speed was faster at night (0.4BL/s) than during a day (0.2BL/s). They swam the shallow water area at night. Catfish frequently moved between upstream and downstream. Catfish tended to act during a day. The average swimming speed was faster during a day (0.3BL/s) than at night (0.2 BL/s). The average swimming depth was 14.3m, and they tended to float about 4m during a day.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.577-583
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• 2011

In 2007, pet food contaminated with melamine caused hundreds of dogs and cats to develop renal failure all over the world. In 2008, over 294,000 infants consumed infant formula and developed kidney stones in China. Further investigation revealed that fish feed also contained melamine; this raised concerns about melamine residues in edible fish tissues, which could have caused the urinary tract stone epidemic. In Korea, catfish fed with assorted feed that included cuttlefish organs that contained melamine developed whitening syndrome and fell dead in some populations in 2008. This event raised suspicions about the toxicity of melamine and all feeds containing melamine were immediately recalled. In this study, we investigated the rates of melamine accumulation and depletion in muscle and viscera of catfish to propose proper withdrawal periods. One group of catfish was fed a commercially available diet that contained 30, 100 and 300 mg melamine per kg diet for 14 days. To investigate residual melamine contents in muscle and viscera, other experimental groups were fed a melamine free diet after being fed melamine for 7 days. The residual amount of melamine was analyzed by LC-MS/MS. The melamine concentration in muscle was estimated to be 3.7 mg/kg after 6 days of feeding with a diet containing 300 mg melamine/kg. After 2 days of culture with a melamine free diet, the residual melamine was depleted and the concentration had decreased from 1.15 mg/kg to 0.19 mg/kg in the muscle of catfish fed a diet containing 300 mg melamine/kg for 7 days. The residual amount of melamine was reduced to 0.03 mg/kg in muscle after 7 days of culture with a melamine free diet and was undetectable after a prolonged culture period of 14 days. Catfish tend to excrete melamine rapidly after oral administration and changes in body color were not observed during the short dosing period.

• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.207-211
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• 2019

Mass mortality in commercially cultured Amur catfish (Silurus asotus), showing symptoms of dermal ulcerations, occurred on a private farm in Mar 2019 in Korea. β-hemolytic bacteria were isolated from the ulcers and kidneys of the fish and identified as Aeromonas veronii. The isolate was resistant to tetracycline and possessed cytotoxic heat-labile enterotoxin (aerolysin/hemolysin). We investigated the genetic determinants associated with tetracycline resistance, and the isolate has been confirmed to simultaneously possess tetA and tetE genes. This is the first report on the occurrence of tetracycline-resistant A. veronii infection related to mass mortality in commercially cultured Amur catfish in Korea.