• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.100-105
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• 2006

This study was conducted to evaluate the effects of extruded pellet (EP) diets, as compared to a raw fish moist pellet (MP) diet for olive flounder, Paralichthys olivaceus, grown in commercial-scale aquaculture for 1 year. Four diets with duplication per diet were formulated for this experiment: two experimental EP diets (EP1 and EP2), one commercial EP diet (CEP), and a raw fish MP diet (MP). The MP diet consisted of 80% frozen horse mackerel and 20% commercial binder meal. Fish weighing $30.1{\pm}0.1 g$ ($mean{\pm}SD$) were distributed randomly to each aquarium as a group of 2,600 fish. Weight gain (WG) and feed efficiency ratio (FER) of fish fed EP2 and MP were higher (P<0.05) than those of fish fed CEP, while those of fish fed EP1 did not differ (P>0.05) from those fed EP2 and MP. However, fish fed the MP diet had a higher survival rate than fish fed the other diets. Fish fed EP2 had higher serum, phospholipids and total protein levels, and lower levels of serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and total cholesterol than fish fed MP (P<0.05). Dorsal muscle and liver proteins and lipid of fish fed EP1 were higher (P<0.05) than those of fish fed CEP, while those of fish fed EP1 and MP did not differ from those of fish fed EP2 (P>0.05). These results strongly suggest that EP1 could be developed to replace MP for grow-out stage production of olive flounder without adverse effects on growth performance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.2
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• pp.85-91
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• 1983

The behaviour of shrimp in response to the trap was much influenced by the type, size and the dimensions of entrance as well as physiological and ecological conditions. The entry and the escape behaviour of shrimp to the model trap were observed in accordance with netting materials, baits, type and slope of entrance, and gathering response were also investigated on the odour of bait extracts in the aquarium from June to August, 1983. Entering shrimp to the circular entrance was significantly more than to the triangular or the square; however, no differences were found in the entry behacior among netting materials i e., P. A, P. E. and cotton. According as the slope of entrance was increased its angle from 0$^{\circ}$ to 90$^{\circ}$, number of entering shrimp was decreased; however, number of escaping shrimp at 30$^{\circ}$or 60$^{\circ}$ with time was fewer than at 0$^{\circ}$ or 90$^{\circ}$. Gathering responses of shrimp on the odours were more sensitive to the flesh of mackerel or the shrimp than to the pickled anchovy, or the pettitioes, while no differences were found between another bait extracts, i e., the shrimp and the flesh of mackerel, the short-necked clam and the horse mackerel, the flesh and the viscera of mackerel.

• Journal of fish pathology
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• v.1 no.2
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• pp.77-85
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• 1988

In March 1987, a bacterial disease occured among cultured tilapia (Oreochromis niloticus), in the aquarium of Fish Pathology Laboratory of National Fisheries University of Pusan. The diseased fish showed abdominal inflamation of ascites. The causative organisms isolated from the kidney were Gram negative rods. On SS agar colonies developed within 48 hours at $25^{\circ}C$. On the basis of the morphological and biochemical characteristics the organisms were identified as Edwardsiella tarda. They were sensitive to chloramphenicol, ampicilline and oxytetracycline. The pathogenicity was proved positive by intraperitoneal injection. Three kinds of antigen were prepared with E. tarda for the immune response in tilapia : i.e., by inactivating the strain with 0.4% formalin for 24 hrs at $25^{\circ}C$ ultrasonicating it 3 times with 5 watts for 30 seconds each time and filtrating it through millipore filter. The formalin killed antigen showed good efficacy at the injection concentration of over $10^7$ cells per fish of 50g. All the immunized tilapia showed only a little agglutination titer to the three antigens. The highest survival rate was recorded in challenged tilapia immunized with formalin killed cells.

• Journal of Aquaculture
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• v.16 no.3
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• pp.151-158
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• 2003

This study was conducted to estimate the effects of residual chlorine dioxide ($CIO_2$) in chlorinated seawater on survival and physiological responses (hematocrit: Ht, hemoglobin: Hb, serum electrolyte and glucose levels, and osmolality) of olive flounder, Paralichthys olivaceus. All the flounders were exposed for 10 min to different concentrations of residual $CIO_2$ just after chlorination for 1 min in each experimental aquarium (EA). ClO$_2$-free seawater was continuously supplied to each EA after 10 min exposure to $CIO_2$. By means of probit analysis, the median lethal times (LT$_{50}$, min) of flounder exposed to 0.43 and 0.51 ppm $CIO_2$, were at 103 and 32 min, respectively. In the range from 0.34 to 0.51 ppm $CIO_2$, the values of Ht, Hb, electrolytes and osmolality of fish exposed to $CIO_2$ were significantly elevated as elapsed time and residual concentrations of $CIO_2$ increased after chlorination. The levels of Ht, Hb, electrolytes and osmolality in flounder exposed to 0.27 ppm $CIO_2$ were not significantly different compared to control fish, which were maintained in $CIO_2$-free seawater; however, the levels of serum glucose were significantly increased with elapse times.

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.62-65
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• 2010

Arowana (Scleropages formosus) is the most valuable group of ornamental fishes and very much in demand in the ornamental fish trade and commands high price ranging from hundreds to thousands of dollars per fish. In this paper, we described a case of mortality of arowana from a private aquarium in Korea. A bacterial pathogen from fish organs (brain, kidney, liver) was cultured, identified and confirmed using Vitek System 2, API 20E test, multiplex PCR and 16S rRNA gene sequencing. The morphological and biochemical properties of the bacterium isolated from the brain, kidney and liver of the fish were similar to Aeromonas sobria. Positive amplification products using the multiplex PCR assay for detection of A. sobria were obtained from these organs. The 16S rRNA gene of the isolates from fish was identical and exhibited 100% sequence similarity with A. sobria (AY987762.1) strain available from GenBank. This bacterium contained hemolysin gene, a virulence factor that plays an important role in outbreaks of disease and is pathogenic to humans as well as in fish. Although this opportunistic bacterium was isolated from a fish without any external symptoms, this pathogen may act as a reservoir and enhance chances of zoonosis to human such as during handling.

• Journal of Aquaculture
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• v.10 no.1
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• pp.25-32
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• 1997

Develoment precess and characteristics of eggs of the geoduck clam, Panope japonica are reporting in this study. Eggs and sperm were excised from gonad, artificially fertilized in an aquarium, reared under various temperature regimes, and record and record the larval period and the time need to reach a certain larval stage from ferilization. Unfertilized eggs of P. japonica appeared to be oval with a mean diameter of $70\mu$m and they became spherical after fertilization. The eggs of P. japonica can be classified as demersal. At a constant water temperature of $ 11^{citc}C$, it took 4 hours form fertilization to become four-cell stage, two days to become trochophore larvae, three days to become D-shape larvae, twenty-three days to become umbo stage, and thirty-six days to become fully grown veliger ready form settlement. A negative correlation was observed between the water temperature and the larval period of P. japonica. From fertilization to D-shape larvae, it took five days at 8$^{\circ}C$, while it was only two days to become D-shape larvae at $ 17^{citc}C$. Time required to D-shape larvae from fertilization was proportional to temperature, and the relationships were expressed as follows : To 8-cell stage, 1/t=0.0209 w-0.1167 (r=0.9967) To blastula stage, 1/t=0, 0055 w-0.0192 (r=0.9825) To trochophore stage, 1/t=0.0034 w-0.0155 (r=0.9907) To D-shape larvae stage, 1/t=0.0014 w-0.0023 (r=0.9843) (t, time in hours ; w, water temperature) Bioligical minimum temperature for egg development was calculated as 3.82$^{\circ}C$ in average.

• Journal of Aquaculture
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• v.10 no.4
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• pp.417-424
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• 1997

This study was carried out to investigate the effects of experimental formulated diets, commercial diets and natural diet(dried Undaria) on growth and body composition of Haliotis discus hannai. Experimental diets was formulated to provide 34.1% protein and 7.5% lipid, and prepared by different $CaCl_2$ concentration (5, 10 and 15%) and dipping time (10, 20 and 60 second) in solution. The juvenile abalone average weighing 0.3g were distributed in a flow-through aquarium system using a cmpletely randomized desing with 13 diets and 3 replictes per diet (50 abalone/tank), and fed diets for 17 weeks. The abalone fed the time nine experimental formulated diets and two commercial diets showed better growth performance than that of natural diets. No significant differences were found among abalone fed the experimental diets and commercial diets in survival rate, weight gain, soft body weight and soft body composition (P>0.05).

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.115-123
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• 2009

Grazing effects of a freshwater bivalve, Unio douglasiae, on both the phytoplankton communities of cold- and warm eutrophic lakes were examined in aquarium with sediment. The animal U. douglasiae used in the study was collected from the Gunsan (Jeonbuk), acclimatized in laboratory aquaria with washed sand from the mussel collection stream, and starved for $2{\sim}3$ days by the experiment. Grazing experiments were performed with the surface waters collected from Lake Ilgam (Seoul) in the cold period (March 31, 2008), and the warm period (June 19, 2008), respectively. Results clearly showed that the concentration of chlorophyll-a (chl-a) and algal abundance were decreased with the increase of mussel-treated density and treated-time. At the same animal density, U. douglasiae effectively decreased the chl-a of cold-lake water (CW), compared to warm-lake water (WW). Increasing the mussel density, the filtering rate (or algal abundance) of the mussel on the CW gradually decreased, while those of WW did not increase or decrease. Major phytoplankton species Synedra ulna and Stephanodiscus hantzschii, and Scenedesmus ecornis in CW, and those of Tetraedron regulare and Pediastrum simplex in WW, were quickly decreased after the mussel stocking. Interestingly, cyanobacterium Microcystis aeruginosa in WW, not dominant species, were less removed. These results suggest that a freshwater bivalve U. douglasiae have a strategic potential to control dense hibernal diatom or green algae, rather than the cyanobacterial bloom in eutrophic water.

• Journal of Life Science
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• v.31 no.12
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• pp.1066-1071
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• 2021

The aim of this study was to examine the metabolic adjustment of lactate dehydrogenase (EC 1.1.1.27, LDH) isozymes to a change in dissolved oxygen (DO) in bluegill (Lepomis macrochirus). After bluegills were adapted to a constant environment in an aquarium, the DO was changed to investigate the activity of LDH isozyme and the relative ratio of subunits A, B, and C for each tissue. When the DO was decreased from 18 ppm to 6 ppm, LDH in skeletal muscle, heart, and brain tissues recovered to the level of control activity within 12, 12, and 6 hr, respectively. LDH activity changed in accordance with a change in DO. The compensation was performed rapidly and is thought to be an important function of LDH in enabling bluegills to adapt to their environment. In bluegill heart, eye, and brain tissues, the relative ratio of subunit A increased and showed a tendency to recover similarly to the subunit ratio of control groups up to 12 hr. It is thought that the anaerobic metabolism using subunit A was increased in the initial stage when DO was changed. In addition, the results revealed that subunit C was more similar to subunit A than subunit B. In bluegills, subunits A and C of LDH seem to be evolutionarily similar. LDH isozymes, mainly containing subunits A and C, are likely responsible for the function of pyruvate reductase, which plays a role in making the bluegill adapt to a hypoxic environment through anaerobic metabolism.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.164-174
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• 2021

The study examines the shearing and crushing characteristics of land-derived subaqueous granular materials in a gravel-bed river. A series of large-sized ring shear tests were performed to examine the effect of shear time and shear velocity on the shear stress characteristics of aquarium gravels with a 6-mm mean grain size. Three different shear velocities (i.e., 0.01, 0.1, and 1 mm/sec) were applied to measure the shear stress under the drained (long-term shearing) and undrained (short-term shearing) conditions. Different initial shear velocities, i.e., 0.01→0.1→1 mm/sec and 0.1→0.01→1 mm/sec, were considered in this study. The test results show that the grain crushing effect is significant regardless of drainage conditions. The shear stress of coarse-grained materials is influenced by initial shear velocities, regardless of the drainage conditions. In particular, particle breakage increases as grain size increases. The shearing time and initial shear velocity are the primary influencing factors determining the shear stress of gravels. The granular materials may be broken easily into particles through frictional resistance, such as abrasion, interlocking and fracture due to the particle-particle interaction, resulting in the high mobility of granular materials in a subaqueous environment.