• Korean Journal of Ichthyology
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• v.13 no.4
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• pp.248-253
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• 2001

An histological study was conducted to determine the initial treatment time and treatment duration in the use of sex-reversal hormones in relation to gonadal development and sexual differentiation in the bagrid catfish, Leiocassis ussuriensis. The primordial germ cell, which could be recognized from one-day-old fry, began to protrude into the peritoneal cavity between the mesonephric duct and the gut. The primordial gonad with a genital ridge was developed at 5~10 days after hatching. Sex differentiation of the ovary was identified by the ovarian cavity and meiotic oocytes from 20-day-old larvae. Testicular differentiation was also identified by spermatogonial cells from 20-day-old larvae. It may therefore be concluded that this species belongs to the differentiated type of gonochoristic teleost.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1478-1486
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• 2014

The present experiment was conducted to evaluate the efficacy of dietary fermented by-product of mushroom, Pleurotus ostreatus, (FBPM) as a fish meal (FM) replacer in juvenile Amur catfish, Silurus asotus. A total number of 225 fish averaging $5.7{\pm}0.1g$ ($mean{\pm}standard$ deviation) were fed one of the five experimental diets formulated to replace FM with FBPM at 0%, 5%, 10%, 20%, and 30% ($FBPM_0$, $FBPM_5$, $FBPM_{10}$, $FBPM_{20}$, and $FBPM_{30}$, respectively). At the end of eight weeks of the experiment, average weight gain (WG) of fish fed $FBPM_0$ or $FBPM_5$ were significantly higher than those of fish fed $FBPM_{20}$ or $FBPM_{30}$ diets (p<0.05). However, there was no significant differences in WG among the fish fed $FBPM_0$, $FBPM_5$ or $FBPM_{10}$, and between fish fed $FBPM_{10}$ or $FBPM_{20}$, and also between those fed $FBPM_{20}$ or $FBPM_{30}$ diets. Lysozyme activity of fish fed $FBPM_0$ or $FBPM_5$ were significantly higher than those of fish fed $FBPM_{10}$, $FBPM_{20}$ or $FBPM_{30}$ diets (p<0.05). The chemiluminescent response of fish fed $FBPM_5$ was significantly higher than those of fish fed $FBPM_0$, $FBPM_{20}$ or $FBPM_{30}$ diets (p<0.05). Broken line regression analysis of WG suggested that the maximal dietary inclusion level for FBPM as a FM replacer could be 6.3% without any adverse effects on whole body composition and on serological characteristics. Therefore, these results may indicate that the maximal dietary inclusion level of FBPM as a FM replacer could be 6.3% in juvenile Amur catfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.31-36
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• 1998

In order to find out the effect of supplemented diets with squid intestine on the catfish, growth and body compositions of catfish (Parasilurus asotus) were investigated for 112 days with the four experimental diets of different lipid levels. The higher lipid level of diets with squid intestine supplement was fed, the higher body weight was gained (p<0.05). HSI (Hepatosomatic Index) was the lowest in the diets with $10\%$ squid intestine. There were no significant differences in muscle md skin compositions, however the increasing lipid levels in the diets well reflected in the fatty acid pattern of skin and muscle. The percentage of n-3 polyunsaturated fatty acids such as C20 : 5 and C22 : 6 in tissues was increased according to increase of supplemented squid intestine. Saturated and n-6 fatty acid contents did not show the significant difference.

• Journal of fish pathology
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• v.13 no.2
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• pp.75-86
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• 2000

Monogeneans(Phylum Platyhelminthes) have been known as common parasites onto the skin and gills of cultured freshwater fishes. Infestation with these parasites result in a great loss in aquaculture industry. Some classification studies on these parasites have mostly been conducted in Japan but rarely in Korea. For the purpose of classifying monogenean parasites infesting two Korean freshwater fishes, eel (Anguilla japonica) and catfish(Parasilurus asotus), samples captured from March 1998 to April 2000 were examined. Here we report for the first time in Korea that four different species of monogeneans are identified: Pseudodactylogyrus bini and P. anguillae in eels; Ancylodiscoides infundibulovagina and Ancylodiscoides sp. in catfish.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1229-1235
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• 2015

Juvenile banded catfish(Pseudobagurus fulvidraco, mean length $10.7{\pm}0.42cm$ and mean weight $15.0{\pm}0.23g$) were exposed to varies TAN(total ammonia) concentrations at pH levels of $6.12{\pm}0.51$, $7.00{\pm}0.26$ and $8.04{\pm}0.07$ for 96hrs to check the level of acute toxicity on biofloc technology aquaculture system(BFT). The result showed that cumulative mortalities for juvenile banded catfish at TAN levels 48.95, 55.96, 66.47, and 78.88 mg/L at pH $6.12{\pm}0.51$ were 0, 30, 30, and 50%, respectively. At pH $7.00{\pm}0.26$, its mortalities to TAN 5.20, 11.68, 15.31, and 18.31 mg/L were 0, 10, 20, and 70%, respectively and at pH $8.04{\pm}0.07$, the mortalities to TAN 0.96, 1.49, 2.13, and 3.62 mg/L were 10, 20, 40, and 100%, respectively. Its $96h-LC_{50}$ (median lethal concentration, $LC_{50}$) at pH $6.12{\pm}0.51$, $7.00{\pm}0.26$, and $8.04{\pm}0.07$ were 78.12, 15.87, and 2.21 mg/L for TAN, and 0.05, 0.10, and 0.14 mg/L for $NH_3$, respectively, and the acute toxicity for ammonia to juvenile banded catfish increased exponentially with increase of pH.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.41-48
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• 2015

Juvenile banded catfish(Pseudobagurus fulvidraco, mean length $10.4{\pm}0.37cm$ and mean weight $14.5{\pm}0.46g$) were exposed to several nitrite(${NO_2}^-$) concentrations for 96h at pH levels of $6.18{\pm}0.54$, $6.5{\pm}0.30$ and $7.07{\pm}0.22$. The result showed that cumulative mortalities of fish to ${NO_2}^-$ levels of 12.4, 19.8, 33.9 and 53.6 mg/L at pH levels of $6.18{\pm}0.54$ were 20, 25, 40 and 85%, respectively. At pH $6.5{\pm}0.54$, mortalities to ${NO_2}^-$ 22.4, 36.4, 45.3 and 63.2 mg/L were 25, 35, 50 and 100%, respectively. At pH $7.07{\pm}0.22$, mortalities to ${NO_2}^-$ 25.5, 45.7, 56.3 and 66.4 mg/L were 0, 55, 70 and 100%, respectively. The 96h-$LC_{50}$(median lethal concentration, $LC_{50}$) of fish to several ${NO_2}^-$ concentrations at pH levels of $6.18{\pm}0.54$, $6.5{\pm}0.30$ and $7.07{\pm}0.22$ were assessed in these experiments. 96h-$LC_{50}$ at pH levels of $6.18{\pm}0.54$, $6.5{\pm}0.30$ and $7.07{\pm}0.22$ were 32.68, 40.49 and 45.85 mg/L, respectively. It indicated that acute toxicity of ${NO_2}^-$ to juvenile banded catfish increased with low levels of pH and lengthening of exposure time to ${NO_2}^-$. In particular, smaller fish(mean weight $14.5{\pm}0.46g$) were more sensitive to ${NO_2}^-$ than larger fish(mean weight $81.7{\pm}1.42g$; not published). The 96h-$LC_{50}$ of juvenile banded catfish to ${NO_2}^-$ would be primary guideline for water quality management in the intensive culture system such as RAS and BFT.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.2
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• pp.174-183
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• 2001

During the rapid phase of gonadal development of the freshwater teleost, the catfish (Silurus asotus), the influence of hCG upon the inducement of final oocyte maturation and spawning was investigated electrophoretically and ultrastructurally. The electrophoretic patterns obtained were different in the presence and absence of some of the major or minor zones, because of the hormone level in catfish. The vitellogenin of hormone-treated fish was stained more intensively than that of sham-treated fish. These proteins showed some minor or main bands of egg extracts which migrated at positions corresponding to molecular weights of approximately 90,000. However, the thickness of electrophoretic band in molecular weight for hCG-treated fish was slightly lower than that for saline control. It seemed the plasma protein with molecular weight of approximately 45,000 in hCG-treated fish disappeared. In contrast to the control fish, the ovaries in the catfish treated with hCG shows a marked ultrastructural change under the electron microscope. No dilated profiles were seen in the granulosa cells of the mature oocyte before ovulation. After germinal vesicle breakdown (GVBD), the zona radiata interna (ZRI) becomes more compact, and there is a loss of all the processes from the pore canals. There is a wide space between the vitelline membrane and zona radiata. Also, during final maturation, the microvillar processes from the oocyte are seen no longer to penetrate deeply into the extracellular spaces of the overlying granulosa cells, and the reticulate patterns of the zona radiata interna becomes occluded, giving the zona radiata a more solid appearance. It has been possible to initiate 100% oocyte maturation in yolk granules and follicles in vivo by treatment with hCG and a high water temperature ($27^{\circ}C$). In hCG-treated fish, the percentages of successful artificial fertilization and hatching were maximal at 15 h after a single injection. It seems clear that a long acting preparation containing hCG can be successfully used in prespawning fish to advance the final events of gonadal maturation and initiate spawning. Further studies are necessary to evaluate the potential of hCG to either stimulate or inhibit the reproductive development of fish at other stages of the seasonal reproductive cycle.

• Journal of Aquaculture
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• v.20 no.3
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• pp.184-189
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• 2007

Treatment conditions for the induced diploid gynogenesis, a maternal-exclusive form of artificial parthenogenetic reproduction, were optimized in bagrid catfish (Leiocassis ussuriensis, Siluriformes). Optimal amounts of ultraviolet (UV) irradiation for the genetic inactivation of spermatozoa in bagrid catfish and Pseudobagrus fulvidraco were proven to be ranged from 3,600 to 4,800 $ergs/mm^2$ based on the examination of viability of embryos and haploid incidence. Haploid embryos were restored to diploidy by preventing the extrusion of the second polar body using cold shock treatment. Thermal treatments (4 or $6^{\circ}C$ for 30, 40 or 50 min) were carried out 3, 5 or 7 min post insemination. Best scores for embryo viability (38.6% of total eggs taken) and incidence of normal diploidy (87.9% of hatched larvae) were observed at the embryo group treated at $4^{\circ}C$ for 40 min, 5 min after insemination. Restoration of gynogenetic diploidy was confirmed based on the absence of haploid syndrome, cell size and/or nucleolar organizing region (NOR) counts.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.22-31
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• 2017

To find out the stress response and wound healing of surgical incisions, we analyzed the change of stress hormone and the healing process in far eastern catfish, Silurus asotus. The survival rate of the clove oil (1,000 ppm) anesthesia group after surgery was about 90% in 3~42 days, while no anesthesia group showed about 74%. Thus, the survival rate after anesthesia group was higher than that of the no anesthesia group. The plasma cortisol concentration of the clove oil anesthesia group was higher than that of the no anesthesia group (P<0.05). In addition, the plasma glucose concentration of clove oil anesthesia group was higher than that of the no anesthesia group (P<0.05). The plasma lactic acid concentration of clove oil anesthetized group was higher than that of the not anesthetized group (P<0.05). On the 14 days and 28 days after surgery, there were still stitching fiber of suture and swimming behavior was not active. On the 35 days after surgery, trace of the suture has almost disappeared on the outside of the fish. Finally, 42 days after surgery, stitching fiber was not visible, and the sutured wounds were distinctly recovered. The results of this study showed that the anesthesia group showed higher survival rate and received less postoperative stress than that of the no anesthesia group. Surgical wound healing in the catfish of this study was shown to be successful when using anesthetics.

• Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.359-365
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• 2015

We investigated the effects of dietary lipid sources on growth and fatty acid composition of juvenile Chinese longsnout catfish. Triplicate groups of fish (initial average weight, 3.8 g) were fed four diets containing either fish oil (FO), soybean oil (SO), linseed oil (LO) and lauric acid (LA) for 10 weeks. There were no differences among the groups in body weight, feed intake, feed efficiency, protein efficiency ratio, and body proximate composition of fish fed the diets containing different lipid sources (P > 0.05) during the study. However, fatty acids compositions of the whole body were influenced by dietary lipid source. Fish fed the SO diet had high concentration of linoleic acid, whereas those of fish fed the LO diet were rich in linolenic acid and arachidonic acid. Fish fed the FO diet had significantly (P < 0.05) higher levels of monounsaturated fatty acids such as 18:1n-9 and 20:1n-9 than those of fish fed the SO and LO diets. Eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) composition of body were not influenced by dietary lipid source. The results suggest that each of FO, SO, LO or LA can be used as a lipid source in the diets of Chinese longsnout catfish without any negative effects on growth and feed utilization and these data demonstrate the potential impact which dietary fat composition can change the body fatty acid profile.