• 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.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.415-420
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• 2000

Distribution of S-100 protein-immunoreactive cells in the gastrointestinal tract of the catfish, Silurus asotus was investigated by PAP method. S-100 protein-immunoreactive cells were mainly observed just under the epithelium of the gastrointestinal tract. Immunoreactive cells were distributed numerously in the stomach and moderately in the middle part of the intestine, however, a few in the upper and lower part of the intestine.

• Journal of Aquaculture
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• v.17 no.1
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• pp.8-11
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• 2004

Milt of the catfish was stripped into immobilizing solution containing 175 mM NaCl and 30 mM Tris at pH 7.8 and was successfully cryopreserved after a stepwise freezing procedure. After stepwise thawing, motility of spermatozoa was slightly lower than that of fresh sperm. Batches of 40-80 eggs were fertilized with cryopreserved spermatozoa, after thawing and activation in solution containing 50 mM NaCl, 20 mM Tris and HCl at pH 7.8; this resulted in 62.2% fertilization success, compared to 70.6 % with fresh sperm.

• Journal of Aquaculture
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• v.14 no.2
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• pp.67-71
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• 2001

Phosphorus is an essential element for growth and metabolism in fish. However high levels of phosphorus in the feed can lead to poor water quality of pond, and can also be a potential source of pollution, when pond water is released to the environment. In this study phosphorus supplemented diets containing 0.0, 0.9 or 1.9% of (dicalcium) phosphate were offered to channel catfish and changes in water quality of ponds and phosphorus levels in fish were measured. Higher level of (1.9%) supplementation of phosphorus in diet resulted in higher concentration of T-P and SRP in pond waters. Also it produced negative effects on fish production by lowering feed coefficient and rate of increment in body weight. Surplus phosphorus can affect fish growth and water quality of pond.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.313-318
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• 2004

Di-2-ethylhexyl phthalate (DEHP) is a widely used plasticizer known to be a suspected xenoestrogen and a causative agent of oxidative damage to the RBC cell membrane ir vitro. We evaluated the toxic effects of a scarcely documented aquatic environmental pollutant, DEHP, on selected haematological endpoints in the bagrid catfish, Pseudobagrus fulvidraco. Bagrid catfish were exposed to DEHP (300, 1,000 mg DEHP kg body weight$^{-1}$) through thrice intraperitoneal injection and effects were assessed in blood of the exposed organisms. Haematological property, serum organic and inorganic chemistry were monitored in blood of Bagrid catfish. DEHP exposed-fish showed erythropenia; low hematocrit (Ht) and hemoglobin (Hb) content and red blood cell count showed a significantly higher than in that of the control group. The treatment group showed a significantly lower concentration of serum total protein, cholesterol and triglyceride compared with those in the control group. The value of calcium and osmolality were significantly decreased in the DEHP treatment group, compared with the control group.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.310-314
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• 2013

This study investigated the utilization of beef tallow and dextrin as non-protein energy sources in the diet of juvenile far eastern catfish Silurus asotus. Three replicated groups of juveniles (initial mean weight of 3.6 g) were fed diets containing high levels of beef tallow or dextrin for six weeks. The final mean weight of fish fed on a 17% lipid diet with a high level of beef tallow was significantly higher than that of fish fed on a 9% lipid diet with a high level of dextrin (P=0.04). No significant differences were observed in the feed efficiency and protein efficiency ratio of fish fed on the experimental diets. Crude lipid content and the C18:0, C18:1n-9 and C18:2n-6 contents of whole-body fish were significantly affected by diet (P<0.05). The results of this study suggest that beef tallow is better than dextrin as a non-protein energy source for improving the growth of juvenile far eastern catfish, and that beef tallow could be economically used as an ingredient in practical feed.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.126-133
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• 1999

Ultrastructure of the zona radiata and the micropyle of ripe eggs in the rainbow trout (Oncorhynchus mykiss), catfish (Silurus asotus) and loach (Misgurnus anguillicaudatus) were examined by light, scanning and transmission microscopes. The egg micropyle of rainbow trout and catfish consists of a funnel-shaped vestibule and a tapered canal transversing the zona radiata. The micropyle of rainbow trout and catfish showed the similar structure with flat pit and long canal. The micropylar wall showed the clockwise spiral structure in rainbow trout. The micropyle of the loach showed the type with a hollow pit leading into a short canal and the micropylar wall showed the counterclockwise spiral structure. There are numerous and various size pores at the surface area around the opening in every experimented fish. Interconnecting ridges were observed in the unfertilized eggs of every fish.

• Progress in Medical Physics
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• v.9 no.2
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• pp.95-104
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• 1998

The dynamic properties of the 3rd-order neuron of the retina was investigated by using conventional intracellular recording techniques. Experiments were performed in the superfused retina-eyecup preparation of the channel catfish, Ictalurus punctatus. The cornea, iris, lens, and vitreous were removed by absorption with Kimwipe tissue under the dissection microscope thereby exposing the retina in a hemi -eyecup. The electrical signal was amplified by electrometer, viewed on oscilloscope. Regular signals from the cells were recorded on a penwriter and stored by data recorder and computer. Full-field, spot or annular light stimuli were generated on a computer monitor and focused onto the retina. Baclofen hyperpolarized the dark membrane potential, suppressed sustained component and enhanced transient component of the ON-sustained cell with a large transient component, but did not affect the surround antagonism of the cell. Baclofen selectively suppressed responses evoked by moving bar light stimuli on the ON-OFF transient cell. The results suggest that transient cells have directional selectivity in the inner retina. These dynamic properties of amacrine and ganglion cells were modulated by baclofen. Therefore, it is presumed that there is baclofen-induced directional selectivity in ON-OFF transient cells in the catfish retina.

• Korean Journal of Veterinary Service
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• v.16 no.2
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• pp.103-110
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• 1993

The Aeromonas strains were isolated from diseased cultured catfsh (Silurus asotus) in the ponds near by Gochang of Chunbuk. The present isolates were identified as A. hydrophila based on their biological and biochemica1 characteristics. The isolates of A. hydrophila were named GC-1, GC-2, GC-3, GC-4 and GC-5, Five strains were grew optimally at temperatures $35^{\circ}C,$ pH 7.5 and in 0.5 to l% NaCl. This bacterium(GC-1) was injected into health catfish in order to prove the causative agent of ascites and haemorrhagic ulcers. The symptoms in cat fish infected by this challenge method were observed to be very similar to the symptoms of a natural infection, but controls did not show any abnormal symptoms during the experimental period. At 24 post-injection, the red spot developed around the injection site and the haemorrhagic ulcers was extended near the gill and ventral fin. Five strains were tested for drug sensitivity by plate method. All strains were sensitivity to gentamicin and resistant to penicillin, streptomycin and tetracycline.