• Journal of Marine Bioscience and Biotechnology
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• v.2 no.2
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• pp.94-101
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• 2007

The status of recently expanded exotic pangasiid catfish Pangasius hypophthalmus, Pangasiidae farming in rural Bangladesh has been studied for finding research needs, through knowing the culture methods, associated activities and problems, to make the farming sustainable. Data were collected using participatory rural appraisal (PRA) tools in nine villages in three upazilas (sub-district) of Mymensingh district. The farmers have not got any formal training and have developed their knowledge on farming the fish through practice over years and sharing of knowledge among fellow farmers. Linked industries, e.g. hatcheries, nurseries, feed mills, trading of feed and fish etc. have developed that created employment opportunities. Most of the farmers produce two crops a year. About 90% of the farmers were found to practice mono culture of pangasiid catfish at high stocking density. The feeding rates started from 10-15% of the body weight per day at fingerling stage that reduced to 4-6% with growth. The average yield was found to be 25 tonslha/year. The livelihood of the farmers has been improved through farming the fish. Women and children were rarely engaged in the activities. The identified major problems in farming the fish were water quality deterioration, high feed costs and declining consumer demand and market price.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.337-344
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• 2015

The purpose of this study is to determine the effects of vibration on primary (e.g. plasma cortisol), secondary (e.g. plasma glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), $Na^+$, $K^+$ and $Cl^-$) and tertiary (e.g. mortality) stress responses in cultured catfish, Silurus asotus. For this purpose, three groups (one control group and two stress groups) were set up. The control group was exposed to vibration corresponding to 48 decibel (dB) volt (V) (produced using electric vibrators) for 15 minutes per hour every day, and the two stress groups were exposed to vibrations corresponding to 58 and 68 dB (V) (produced using the same electric vibrators), equally, for 15 minutes per hour every day. Blood was sampled at day 0 (before starting vibration stress tests), and at days 1, 3, 5, 7, 9 and 11 (after starting vibration stress tests). According to the results, the catfish physiologically showed ''typical'' stress responses when they were exposed to chronic vibration. This indicates that such chronic vibration caused substantial stress to catfish; especially, persistently elevated plasma AST and ALT levels observed caused adverse effects to them. In conclusion, chronic vibration could significantly affect hematological characteristics in catfish.

• 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.

• Development and Reproduction
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• v.22 no.4
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• pp.319-329
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• 2018

The experiment was conducted for 210 days to determine the effect of feeding, and starvation, and exposure to sodium nitrite ($NaNO_2$) on the survival, physiological changes, hematological parameter, and stress response of Far Eastern catfish, Silurus asotus. The survival of the starved group was lower than that of the fed group during the experiment. Starvation resulted in retardation of growth, which provides an example of fish that failed to continue to grow and remain in a good condition. Blood analyses (cortisol and glucose) showed significant differences of stress response between the fed and starved groups exposed to $NaNO_2$ at the conclusion of the experiment (p<0.05). These results suggest that all nutritional parameters used for starvation and feeding with $NaNO_2$ stress in this experiment appear to be a useful index of nutritional status in Far Eastern catfish.

• Ocean and Polar Research
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• v.27 no.1
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• pp.109-113
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• 2005

To facilitate estimation of the barbel size of a striped sea catfish, Plotosus lineatus Thumberg total length (TL) and head length (HL) against body weight (BW), HL against TL, and 1st maxillary barbel $(MxBL_1)$, 2nd maxillary barbel $(MxBL_2)$, 1st mandibular barbel $(MnBL_1)$ and 2nd mandibular barbel $(MnBL_2)$ against HL were regressed. The relationship of TL and HL for BW were described by the equation $TL=50.9373BW^{0.3072}\;(r^2=0.9898)$ and $HL=11.2938BW^{0.3144}(r^2=0.9572)$, respectively. The relationship of HL for TL was described by the linear equation $HL=0.1982TL+2.1996(r^2=0.9568)$. The relationship of each barbel for HL described by the equation of $HxBL_1=0.04420HL+0.3105(r^2=0.9615),\;MxBL_2=0.4592HL+0.5321(r^2=0.9519), MnBL_l=0.4057HL+1.9824 (r^2=0.9465)\;and\;MnBL_2=0.4355HL+1.8010(r^2=0.9429)$. Knowledge of the relative growth patterns about each barbel of this species is important for the propagation of seed as stock for large-scale striped sea catfish culture.

• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.81-89
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• 2008

An experiment was conducted for 80 days to determine the effect of feeding and starvation on the survival, growth, gonad-somatic index (GSI), hepato-somatic index (HSI), viscera index (LSI), the morphometric changes and hematological parameter in a cultured catfish, Silurus asotus. The survival and growth of the starved group was lower than those of the fed group during the experiment. Starvation resulted in retardation of growth, which provides examples of the reduction of final body weight, growth rate of body weight, specific growth rate and condition factor, whereas the fed group continued to grow and remained in good condition. Blood analysis (cortisol, glucose, aspartate aminotransferase, alanine aminotransferase, red blood cell and hemoglobin) showed significant differences between the fed and starved groups at the end of the experiment. These results suggest that all nutritional parameters used for starvation and feeding in this study appear to be a useful index of nutritional status in the cultured catfish.

• 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.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.530-531
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• 2001

Out of 20 primers, 6 generated 1349 highly reproducible RAPD markers, producing approximately 5.2 polymorphic bands per primer in catfish(Sizurus asotus) population from Kunsan. The electrophoretic analysis of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPD) products showed the middle levels of similarity between different individuals in population from Kunsan. That is to say, the degree of similarity varied from 0.40 to 0.54, with the average of 0.46, as calculated by bandsharing analysis. (omitted)

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.8
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• pp.1053-1061
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• 2004

Of the 20 arbitrarily chosen primers, six oligonucleotides decamer primers were used on the basis of the number of the polymorphisms generated in catfish (Silurus asotus) from Yesan and bullhead (Pseudobagrus fulvidraco) from Dangjin in Korea. Six primers were used generating a total of 602 scorable bands in catfish and 195 in bullhead population, respectively, ranging in size of DNA fragments from less than approximately 100 to larger than 2,000 base pairs (bp). Six primers yielded 199 polymorphic fragments (33.1%) in catfish and 47 (24%) in bullhead, respectively. In the present study, a total of 328 common fragments (an average of 54.7 per primer) were observed in catfish population, whereas 84 (an average of 14.0 per primer) in bullhead. The total number of specific fragments in catfish and bullhead population were 76 and 64, respectively. In catfish population, random decamer, OPA-17 (GACCGCTTGT) generated the highest number of fragments (a total of 141) in comparison with other primers used, with an average of 11.8. The common bands in the molecular weight of 300 bp generated by random primer OPA-06 (GGTCCCTGAC) were present in every individuals in bullhead population. The major polymorphic bands in the molecular weight of 100 bp generated by OPA-17 were identified in lane 14, 15, 17, 18, 19 20 and 21, which were identifying species in bullhead population. The average bandsharing values (BS values) of all of the samples within catfish population ranged from 0.575 to 0.945, whereas 0.063-1.000 within bullhead population. The bandsharing value (index of similarity between individuals) between individual No. 5 and No. 9 showed the highest level within catfish population, whereas the bandsharing value between individual No. 1 and No. 2 showed the lowest level. The single linkage cluster analysis resulted from four primers, indicating four genetic groupings composed of group 1 (C1-C10, all of the catfish samples), group 2 (B11, B12, B13, B14, B16, B17, B18, B19), group 3 (B15) and group 4 (B20 and B21). The dendrogram reveals close relationships between individual identities within two species populations and individuals derived from the same ancestor, respectively. However, genetic distances between two species populations ranged from 0.124 to 0.333. The shortest genetic distance (0.042) displaying significant molecular differences was between individual No. 6 and No. 9 catfish population. The shortest genetic distance (0.033) displaying significant molecular differences also was between individual No. 18 and No. 19 in bullhead population. Reversely, the genetic distance of individual No. 20/21 among individuals in bullhead population was highest (0.333). This result showed that bullhead No. 20 and 21 were distinct from other individuals within bullhead population.

• Development and Reproduction
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• v.22 no.2
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• pp.165-174
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• 2018

The aim of study is to contribute to this knowledge-base by investigating the respiratory function, the metabolic rate and the difference of physiological responses un-der low water temperature ($20^{\circ}C{\rightarrow}15^{\circ}C$) stress be-tween diploid and triploid far eastern catfish, Silurus asotus. During the 48 hrs of water temperature stress exposure time, the respiratory frequencies, $CO_2$ and ${NH_4}^+$ concentrations of diploid had higher values than those of triploid (p<0.05). However, pH of triploid was higher than those of diploid (p<0.05), and oxygen consumption rate was not different between diploid and triploid (p>0.05). The level of plasma cortisol and plasma glucose of triploid was lower than those of the diploid (p<0.05). However, in case of lactic acid, there were not significant between triploid and diploid (p>0.05). These results suggest that diploid was more sensitive for low water temperature stress response than triploid in this species.