• 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.

• The Korean Journal of Zoology
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• v.35 no.3
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• pp.263-270
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• 1992

Responses of immunoreactive atrial natriuretic peptide (ir-ANP) to environmental temperature were studied in the freshwater catfish, Silums usotus, acclimated at various temperatures for one week. According to increase in environmental temperature, plasma sodium and chloride concentrations, and osmolality were significantly increased, while hematocrit showed a marked decrease. When the catfishes frere acclimated at cold $(3^{\circ}C)$ or warm $(18^{\circ}C)$ temperatures, ir-ANP contents in the atrium and bulbus arteriosus were significantly lower than those at $9^{\circ}C.$ However, ventricular contents of ir-ANP urere not different among the three groups.Levels of plasma ir-ANP in the catfish increased in response to the increment of acclimated temperature. On the basis of these results, we suggest that the environmental temperature may modulate synthesis and secretion of ir-hUP in the fish. We also suggest that changes of plasma ir-ANP levels may be associated with the control of body fluid homeostasis.

• Development and Reproduction
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• v.23 no.2
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• pp.183-191
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• 2019

The objective of this study is to evaluate the anesthetic effects of clove oil and tricaine methanesulfonate (MS-222) on the Far Eastern catfish, Silurus asotus, by measuring the times to anesthesia and recovery. Each anesthetic effect of clove oil and MS-222 was tested in two groups of fish with different body sizes: a group of small fish (mean body length: $15.5{\pm}1.58cm$, mean body weight: $50.1{\pm}5.91g$, n=20) and a group of large fish (mean body length: $31.5{\pm}4.19cm$, mean body weight: $302.1{\pm}15.22g$, n=20). The anesthetics were used at concentrations of 200, 300, 400, 500, and 600 ppm. The results showed significant relationships between the concentration of the anesthetic and the body size of the fish. Each of these variables showed statistical significance (p<0.05). The time to anesthesia decreased linearly with increasing concentration in the large fish for both clove oil and MS-222 (p<0.05). Based on an optimal anesthetic time of approximately 1 min, the preferred concentrations of the anesthetics were 500 ppm for clove oil and 600 ppm for MS-222. Both the anesthetic time and the recovery time were shorter for the small fish than for the large fish (p<0.05). Our study showed that the smaller-sized Far Eastern catfish was more easily anesthetized and recovered more rapidly from anesthesia than the larger-sized fish.

• Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.299-303
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• 2012

Barbel structure and regenerated barbel length in the juvenile Chinese longsnout catfish Leiocassis longirostris (G$\ddot{u}$nther), were evaluated. The barbles consisted of an epidermis, a dermis, and a central rod. The epidermis harbored taste buds, granular cells and epidermal cells. The taste buds were basophilic and situated along the distal portion of the epidermis. The dermis was composed of loose connective tissue containing blood vessels pigment cells. The innermost central region was cartilage enclosed within layers of muscle layers. After 30 days, the regenerated barbel length measured $0.92{\pm}0.404mm$ at $15^{\circ}C$ (regenerated growth curve: y = 0.5085x + 4.0678, $r^2$ = 0.9654, where y is regenerated length and x is experimental period in days), $1.88{\pm}0.521mm$ at $20^{\circ}C$ (y = 0.1806x + 4.808, $r^2$ = 0.9822), and $6.44{\pm}0.751mm$ at $25^{\circ}C$ (y = 0.0914x + 4.9918, $r^2$ = 0.9944). Fifteen days after amputation, the regenerated length was significantly longer at $25^{\circ}C$ than at 15 or $20^{\circ}C$ (P < 0.05). The barbels of the Chinese longsnout catfish was the tender and flexible type, and our experimental findings provide evidence of temperature-dependent regeneration. Additional investigation of the behavior and physiology of the Chinese longsnout catfish is needed, particularly histological studies of regenerated barbels and the measurements of the numbers of taste buds per barbel under various environmental conditions.

• Journal of fish pathology
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• v.7 no.2
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• pp.105-112
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• 1994

A new bacterial infection occurred among the cultured Korean catfish, Silurus asotus, in Chunbuk prefecture, Korea, 1993. This disease produced about 30% mortality in the fish for 4 months. The diseased fish was swimming listless at the water surface with head up and tail down, sometimes spinnig in circles. The most outstanding clinical sign was ulceration on the skull and at the base of the pectoral fins. The causative organism was isolated from the brain, kidney, spleen and liver of diseased fish, and identified as Edwardsiella icaluri by the biochemical and biophysical characteristics. After intraperitoneal innoculaton of the isolate, the pathogenicity was proved positive for Korean catfish, S. asotus, and channel catfish, Ictalurus punctatus, but negative for carp, Cyprinus carpio.

• Journal of Aquaculture
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• v.6 no.3
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• pp.187-197
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• 1993

Studies related to water quality in catfish ponds were conducted on commercial catfish production ponds and compared with its receiving streams' water quality in central and west-central Alabama. The ponds were stocked with 10,000 fish/ha. The ponds were aerated nightly (0000-0600 hrs). Fish were fed to satiation at about the same time, six-days a week. In order to assess the pollutional strength of effluents from commercial channel catfish ponds, water samples were collected during each calender season from fall 1990 through summer 1991, and selected water quality variables were monitored. Mean values for water temperature, dissolved oxygen concentration, pH, settleable solids, total suspended soilds, volatile solids, total phosphorus, soluble reactive phosphate, biochemical oxygen demand, total ammonia nitrogen, nitrite, nitrate, and total Kjeldahl nitrogen were basically the same (P> 0.05) between samples taken from the surface and near the bottom. Concentrations of most water quality variables of catfish ponds were higher than those of receiving streams, and especially it had much higher average concentrations of nitrogen and phosphorus than streams.

• Korean Journal of Ichthyology
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• v.21 no.2
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• pp.100-105
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• 2009

Histological study of normal and albinic catfish Silurus asotus produced in aquaculture has been carried out on organs such as the eye, the barbel, the dorsal fin, and the skin (including dorsal, ventral and lateral regions). Although individuals have no differences in morphological appearance, their colors showed clear difference as follows: the normal catfishes were black overall, but the albinic ones have a yellowish-white color over the whole body, red eyes and white barbels. All the organs investigated were fundamentally very similar in structure. Regarding the distribution and density of the melanin pigments, however, the albinic catfish have no melanin in the skin and eye, particularly in the basement membrane of the epidermis and the pigment epithelial layer in the retina, while the normal catfish have lots of melanin. This phenomenon may coincide with the so-called $i^1/i^1$ type of oculocutaneous albinism.

• Journal of fish pathology
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• v.32 no.1
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• pp.21-28
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• 2019

It has been reported that various anti-oxidant substances stimulate non-specific immune responses in fishes. In this study it was examined whether N-acetylcysteine (NAC), a precusor for anti-oxidant glutathione (GSH) synthesis, can modulate non-specific immune function in Far Eastern catfish Silurus asotus. Immune functions were assessed using the respiratory burst activity monitored by chemiluminescence (CL) responses in isolated leucocyte. NAC stimulated CL responses with doses of 10 or 100 mg/kg, but not with 1 mg/kg after 48 hr injection. It was observed with 10 mg/kg NAC that CL activity continued to elevate from 24 hr through 96 hr post-dosing, and returned to the near preinjection level by 10 days. To understand whether NAC can also activate CL activity in vitro, NAC was directly added to isolated catfish leucocytes. It was observed, however, that NAC can not stimulate CL at reasonable concentration ranges in vitro. As NAC is a precursor for the strong anti-oxidant glutathione (GSH), a putative immune stimulator, it was assessed whether GSH can also stimulate CL responses. Observed results show that GSH activated CL both in vivo and in vitro. The data obtained collectively support the proposition that NAC indirectly stimulates non-specific immune functions in catfish by enhancing GSH biosynthesis, but not by direct action of NAC. Such effects may have beneficial significance in aquaculture for practical utilization.

• Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.367-379
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• 2023

The rapid expansion of shrimp production requires a huge amount of protein sources from soybeans and wild-caught fishmeal; both are becoming a shortage. Meanwhile, catfish production and processing is a giant industry in Vietnam, which produce hundred thousand tonnes of protein- and lipid-rich by-products, annually. Using catfish by-products to gradually replace the traditional protein sources in shrimp aquaculture may bring triple benefits: 1) reducing pressure on wild fish exploitation for fishmeal, 2) reducing the environmental impacts of catfish by-products, and 3) increasing the value and sustainability of aquaculture production. In this study, we used catfish by-products to produce fish protein hydrolysate (FPH) and nano-hydroxyapatite (HA) as additives in feed for Pacific white shrimp (Litopenaeus vannamei). The supplement mixture of FPH and HA was added into the commercial diet (Charoen Pokphand Group [CP], 38% protein, and 6.5% lipid) to reach 38%, 38.5%, 40%, 43%, and 44% of the crude protein content. The survival and growth of shrimps were weekly assessed to day 55. The results showed that the shrimp growth was highest at 43% crude protein content in the feed as indicated by an increase of 124% and 112% in shrimp weight and length, respectively, compared to the commercial reference diet. No negative effects of adding the mixture of FPH and HA on the water quality were observed. Vibrio density was lower than 6.5 × 10³ CFU/mL, which is the lowest Vibrio density negatively affecting the shrimp growth and development. These findings indicate that the mixture of FPH and HA are promising additive components in feed for post-larval shrimp L. vannamei diets.

• Genomics & Informatics
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• v.21 no.3
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• pp.39.1-39.15
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• 2023

DNA barcoding without assessing reliability and validity causes taxonomic errors of species identification, which is responsible for disruptions of their conservation and aquaculture industry. Although DNA barcoding facilitates molecular identification and phylogenetic analysis of species, its availability in clariid catfish lineage remains uncertain. In this study, DNA barcoding was developed and validated for clariid catfish. 2,970 barcode sequences from mitochondrial cytochrome c oxidase I (COI) and cytochrome b (Cytb) genes and D-loop sequences were analyzed for 37 clariid catfish species. The highest intraspecific nearest neighbor distances were 85.47%, 98.03%, and 89.10% for COI, Cytb, and D-loop sequences, respectively. This suggests that the Cytb gene is the most appropriate for identifying clariid catfish and can serve as a standard region for DNA barcoding. A positive barcoding gap between interspecific and intraspecific sequence divergence was observed in the Cytb dataset but not in the COI and D-loop datasets. Intraspecific variation was typically less than 4.4%, whereas interspecific variation was generally more than 66.9%. However, a species complex was detected in walking catfish and significant intraspecific sequence divergence was observed in North African catfish. These findings suggest the need to focus on developing a DNA barcoding system for classifying clariid catfish properly and to validate its efficacy for a wider range of clariid catfish. With an enriched database of multiple sequences from a target species and its genus, species identification can be more accurate and biodiversity assessment of the species can be facilitated.