• Fisheries and Aquatic Sciences
• /
• v.14 no.4
• /
• pp.417-420
• /
• 2011

In this experiment, we examined the survival, fertilization, hatching times, and hatching rates of Far Eastern catfish Silurus asotus at pH ranging from 2 to 13 under laboratory conditions. Eggs could be fertilized at pH 3-12. In a hatching experiment, mortality was first observed at pH 13, when all fertilized eggs died within 8 min, followed by pH 2 (30 min), pH 12 (60 min), pH 3 (4 h), and pH 11 (5 h). Hatching only occurred at pH 4-10, with the highest hatching rate at pH 7 (52%) and the lowest at pH 10 (24%). Hatching rates in acid solutions were higher than in alkaline solutions, although the difference was not significant. Hatching was first observed at pH 10, beginning 27 h after fertilization and ending at the 31 h. A clear difference was observed between hatching times, ranging from 31 to 64 h and increasing in order with descending pH.

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

• Korean Journal of Veterinary Service
• /
• v.34 no.1
• /
• pp.75-79
• /
• 2011

The recent outbreak of renal failure in infants in China and in animals in USA and Europe has been determined to be caused by melamine adulterated in the food. In the course of the investigation, cyanuric acid was identified in addition to melamine in the offending food. Fish feeds were also recently found to be contaminated with melamine. The purpose of this study was to characterize the histopathological effect and toxicity potential of different concentrations of melamine and cyanuric acid in the kidney of Japanese catfish (Silurus asotus). The fish were administered melamine and cyanuric acid in combination at the concentrations of 12.5, 25, 50, 100 and 200 mg/kg/day for 3 days by single oral administration dissolved in carboxymethyl cellulose. The results showed that renal crystals were observed in renal tubules and collecting ducts at the concentration over 25 mg/kg dose group and the number of crystals in kidney were in proportion to the concentrations of melamine and cyanuric acid.

• Fisheries and Aquatic Sciences
• /
• v.15 no.1
• /
• pp.9-14
• /
• 2012

The objectives of this research were to improve the film-forming properties of Channel Catfish Ictalurus punctatus skin gelatin (CSG) by cross-linking with transglutaminase (TG), determine and optimize the TG reaction time, and characterize the mechanical and barrier properties of CSG edible film. Cross-linking of CSG was performed by TG for 0, 10, 20, 30, and 40 min at $50^{\circ}C$, and the reaction was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The color and mechanical and barrier properties of edible films fabricated with CSG cross-linked with TG were characterized. Gelatin yields from the extraction ranged from 18.2% to 23.3%. SDS-PAGE exhibited dark bands at 120 and 250 kDa, indicating successful TG-mediated cross-linking. The color of CSG film was not affected by TG cross-linking. The tensile strength of CSG films cross-linked with TG decreased from 42.59 to 21.73 MPa and the percent elongation increased from 42.92% to 76.96% as reaction times increased from 0 to 40 min. There was no significant difference in water vapor permeability of CSG films.

• Journal of Fisheries and Marine Sciences Education
• /
• v.24 no.6
• /
• pp.854-861
• /
• 2012

To investigate the role of water temperatures and photoperidos as environmental cues regulating reproductive rhythm in banded catfish Pseudobagrus fulvidraco, rearing experiments were conducted using sveral rearing regimes conbined with changes in photoperiods and water temperatures during growing and spawning periods. GSI of $23^{\circ}C$ was significantly higher than $18^{\circ}C$ in female, but 9 light of 18 and $23^{\circ}C$ were no difference in male. In case of estradiol, $18^{\circ}C$ and 15 L was higher than other experintal precinct after 20 days. But, end of the experiment, all of experimental precinct were no difference. Testosteron of female was no difference in $18^{\circ}C$-9 and 15 L after 20 days. Testosteron of male was no difference in $18^{\circ}C$-9 L. In case of 11-KT, control level was $0.39{\pm}0.03$ ng/mL and $18^{\circ}C$-9 L was no significantly difference after 20 days. But, 15 L was higher than other experimental precinct.

• Journal of Aquaculture
• /
• v.10 no.1
• /
• pp.63-68
• /
• 1997

The spawning behavior of the silurid catfish, Silurus asotus, was observed from laboratory aquaria after treating with human chorionic gonadotropin (HCG) and injection with pituitary extract of grass carp. The details of the spawning behavior presented here are based upon the observations made from 10 trials with 40 male and 20 female catfishes artificially bred between May and July, 1995. Initial spawning activity started 15 to 16 hours after injection with pituitary extract of grass carp and HCG. The activity was continued with for 2 to 3 hours and repeated mating behavior of the catfish were observed during this period. Compared to the spawning activity of the Japanese catifish, S. biwaensis, S. asotus took a different male position during the period o fsearching its partner. This study also reports some other differences in mating behavior between S. asotus and S. biwaensis.

• Development and Reproduction
• /
• v.22 no.1
• /
• pp.1-8
• /
• 2018

The annual reproductive cycle of the Korean endemic slender catfish, Silurus microdorsalis, was examined histologically regarding water temperature and day length of habitat, gonadosomatic index (GSI), and development characteristics of female and male gonads. The maximum GSI value was found in May, $1.23{\pm}0.33$ and $11.77{\pm}3.23$ for male and female respectively (habitat water temperature $21.5^{\circ}C/13.59hr$ day length). On the other hand, the minimal level was $0.63{\pm}0.10$ in July ($26.5^{\circ}C/14.17$) for male and $1.36{\pm}0.08$ in October ($20^{\circ}C/11.2hr$) for female. We compared and calculated the stages of testis and ovary development process in order to determine the germ cell development characteristics and the reproductive cycle. According to results, we classified the annual reproductive cycle of the slender catfish into five stages: Growing phase (December-February), Mature phase (March-April), Ripe and spawning phase / Releasing phase in male (May-June), Degenerative phase (July-August), and Resting phase (September-November).

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

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.12
• /
• pp.4866-4888
• /
• 2020

One major and time-consuming task in fish production is obtaining an accurate estimate of the number of fish produced. In most Nigerian farms, fish counting is performed manually. Digital image processing (DIP) is an inexpensive solution, but its accuracy is affected by noise, overlapping fish, and interfering objects. This study developed a catfish recognition and counting algorithm that introduces detection before counting and consists of six steps: image acquisition, pre-processing, segmentation, feature extraction, recognition, and counting. Images were acquired and pre-processed. The segmentation was performed by applying three methods: image binarization using Otsu thresholding, morphological operations using fill hole, dilation, and opening operations, and boundary segmentation using edge detection. The boundary features were extracted using a chain code algorithm and Fourier descriptors (CH-FD), which were used to train an artificial neural network (ANN) to perform the recognition. The new counting approach, based on the geometry of the fish, was applied to determine the number of fish and was found to be suitable for counting fish of any size and handling overlap. The accuracies of the segmentation algorithm, boundary pixel and Fourier descriptors (BD-FD), and the proposed CH-FD method were 90.34%, 96.6%, and 100% respectively. The proposed counting algorithm demonstrated 100% accuracy.

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