• Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.441-448
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• 2014

We examined the effects of dietary nutrient content, feeding period, and feed allowance on compensatory growth, food use, chemical composition, and serum chemistry of juvenile olive flounder Paralichthys olivaceus. We placed 720 juvenile fish into 24 400-L flow-through round tanks (30 fish per tank).A $2{\time}2{\time}2$ factorial design (diet: control (C) and high protein and lipid (HPL) ${\time}$ feeding period: 8 and 6 weeks ${\time}$ feed allowance: 100% and 90% of satiation) was applied. Fish were hand-fed twice daily, based on the designated feeding schedule. Weight gain and food consumption were affected by both the feeding period and feed allowance, but not by diet. The food efficiency ratio was not affected by diet, feeding period, or feed allowance, but the protein efficiency ratio and protein retention were affected by diet and feeding period, respectively. We found that the full compensatory growth of fish was not achieved at a restricted feeding allowance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.3
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• pp.342-350
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• 2014

An active stimulating device, such as a fluttering net or canvas attached to the end of a cod end generating a shaking motion, could help to encourage the escape of juvenile fish positioned passively near the net. Field fishing trials using a shrimp beam trawl were carried out to examine the effect on the reduction of juvenile fish or other discard catch by generating a shaking movement of the cod end using an unbiased cap-like round canvas. The mean period of the shaking motion with the round canvas was ~14 s, and the mean amplitude was 0.4 m as measured by peak event analysis and the global wavelet method. The bycatch of juvenile fish in 14 trials decreased by ~30% and by ~25% using a steady cod end for the total bycatch using a shaking cod end in the shrimp beam trawl, while the marketing catch was similar between steady and shaking cod ends. There was no difference in the body size of the shrimp or fish and species composition between the steady and shaking cod ends. Above results demonstrate a new method for bycatch reduction using an active stimulating device, although more detailed studies are needed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.918-924
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• 2020

This study investigated diurnal fasting and postprandial total ammonia nitrogen (TAN) excretion rates in juvenile Oplegnathus fasciatus (rock bream; mean body weight 45.8±1.1 g) at three temperatures (15, 20, and 25℃) in a recirculating system (three replicates). The fish were hand-fed twice daily (09:00 and 17:00 h) with commercial food (46.7% protein) until satiation. The results showed that the fasting and postprandial TAN excretion rates were temperature-dependent. The mean hourly rates were 7.7 (15℃), 10.2 (20℃), and 11.9 (25℃) mg kg fish-1 h-1 for fasting and 34.0 (15℃), 47.8 (20℃), and 60.2 (25℃) mg kg fish-1 h-1 for postprandial. At each temperature, two postprandial TAN excretion peaks were observed 2-4 h after feeding; the second peak was always higher. The TAN loss to nitrogen consumption ratio was 41.1-46.8 % and increased significantly with increasing temperature. Temperature affected fasting and postprandial TAN excretion in juvenile rock bream, providing insight for culture management.

• Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.58-68
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• 2023

This study was conducted to determine dietary threonine (Thr) requirement for juvenile olive flounder (Paralichthys olivaceus). A total of 450 juvenile fish (23.2 ± 0.4 g) were randomly distributed to 18 tanks (215 L) with 25 fish per tank. Experimental diets included with graded levels of Thr at 0.0%, 0.4%, 0.8%, 1.2%, 1.6%, and 2.0% were assigned for triplicate groups of fish and fed two times daily to apparent satiation for 12 weeks. Weight gain, specific growth rate, feed intake, feed utilization and survival were significantly (p < 0.05) increased in fish fed with dietary Thr levels over 0.8%, and no significant differences were observed between 0.8% to 2.3% levels. Non-specific immune parameters of serum lysozyme, myeloperoxidase activity, antiprotease activity, and total immunoglobulin were significantly increased by dietary Thr over 0.8%. Based on the broken-line regression analysis, the Thr requirement for the optimum growth and immune response in olive flounder is likely to be 1.03% in the diet.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.12
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• pp.1794-1799
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• 2008

This preliminary feeding trial was conducted to study the effects of different dietary selenium (Se) levels on growth performance and toxicity in juvenile black seabream, Acanthopagrus schlegeli (Bleeker). Fish averaging $7.0{\pm}0.1g$ ($mean{\pm}SD$) were fed one of the five semi-purified diets containing 0.21, 0.30, 0.52, 1.29 and 12.3 mg sodium selenite ($Na_2SeO_3$)/kg diet (Se 0.21, Se 0.30, Se 0.52, Se 1.29 or Se 12.3) for 15 weeks. After the feeding trial, weight gain (WG), feed efficiency (FE), specific growth rate (SGR) and protein efficiency ratio (PER) of fish fed Se 0.21, Se 0.30, Se 0.52 and Se 1.29 diets were not significantly different, however fish fed Se 12.3 diet showed significantly lower WG, FE, SGR and PER than those of fish fed the other diets (p<0.05). Fish fed Se 0.21, Se 0.30, Se 0.52, Se 1.29 and Se 12.3 diets showed no significant differences in hematocrit (PCV), hemoglobin (Hb) and red blood cells (RBC), however fish fed Se 12.3 diet showed lower values of PCV, Hb and RBC than those of fish fed the other diets. Histopathological lesions such as tubular necrosis and polycystic dilation of tubules in the kidney tissues were observed in fish fed Se 12.3 diet. Se was accumulated in a dose-dependent manner in the liver, kidney, muscle and gill tissues. Based on the results of this preliminary feeding trial, a dietary Se level of 0.21 mg $Na_2SeO_3/kg$ diet could be optimal for proper growth performances, and a dietary Se level of 12.3 mg $Na_2SeO_3/kg$ diet may ultimately be toxic to juvenile black seabream, Acanthopagrus schlegeli.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.6
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• pp.1285-1293
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• 2013

This study was conducted to investigate the effects of dietary inclusion of various additives Solid sulfur, fucoidan, and glucan on growth performance and immune responses in Juvenile olive flounder paralichthys olivaceus. Six experimental diets supplemented with : no additives (CON); 0.5 and 1.0% solid sulfur (S); 0.2 and 0.4% fucoidan (F); 0.1% glucan (G) of these additives diet on a dry-matter basis. Fish averaging $8.2{\pm}0.17g$ were fed one of six experimental diets in triplicate groups for 6 weeks. By the end of the feeding trial, weight gain, feed efficiency, specific growth rate, protein efficiency ratio, hepatosomatic index and condition factor of fish fed diet CON were significantly lower then those of fish fed the all additives diets (P < 0.05). In challenge test, fish were infected by intraperitonel injection of 0.1 ml bacterial suspension with Edwardsiella tarda per fish after the feeding trial. As a result fish fed All additive diet showed a lower cumulative mortality then did fish fed CON diet throughout the challenge test. In conclusion, these results indicated that solid sulfur, fucoidan and glucan enhanced the growth, feed efficiency and non-specific immune activity of juvenile flounder and protect the fish against microbial infections.

• Journal of fish pathology
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• v.17 no.3
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• pp.199-205
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• 2004

Effects of nitrite, ammonia and hydrogen sulfide on survival of the early developmental stages of Fenneropenaeus chinensis were determined under continuous flow-through system. The 96hr-$LC_{50}$ values of mysis stage were 18.4 mg/L, 0.69 mg/L and 13.5 $\mu{g}/L$ for nitrite, ammonia and hydrogen sulfide, respectively; 28.3 mg/L, 1.23 mg/L and 20.7 $\mu{g}/L$ for post larva stage and 39.8 mg/L, 1.73 mg/L and 28.5 $\mu{g}/L$ for juvenile stage, respectively. The Fenneropenaeus chinensis sensitivity for the three pollutants was in the order of hydrogen sulfide>ammonia>nitrite. The mysis/post larva, mysis/juvenile and post larva/juvenile ratios of nitrite, ammonia and hydrogen sulfide toxicity were >1.5, >2.0 and <1.5 times, respectively, and mysis were found to be more sensitive to pollutants than juvenile in all cases.

• Development and Reproduction
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• v.19 no.1
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• pp.25-31
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• 2015

We have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium ($50{\times}50{\times}30cm$). Breeding water temperature was $27.5{\sim}28.5^{\circ}C$ (mean $28.0{\pm}0.05^{\circ}C$) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean $0.74{\pm}0.07mm$, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean $3.84{\pm}0.04mm$, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean $10.9{\pm}1.66mm$), and it had similar silver-colored body shape with its mother.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.2
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• pp.88-95
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• 2016

Most grid sorting has been used to sort out flatfish in shrimp fisheries, while double grid systems have been tested to separate smaller shrimp. The escape of juvenile red seabream through separating panels made with steel grids or large mesh tested for masking effects in a two-species system. Fish behavior was observed in a circulating water tank. The escape rate was 20% greater with the separating codends than with the normal codend in the single-species experiments. The rates in the two-species experiments were 30% or 20% greater than the single-species rates for the normal or separating codends, respectively. The seabream retention rates in the grid separator codend decreased as rockfish retention increased, possibly due to a threat effect. Conversely, the retention rate of both species increased concurrently in the net separator, possibly due to a masking effect. The escape rates of juvenile red seabream varied by compartment in the mesh separating codend. These results suggest that grid separating codends can be used in the field as towed fishing gear to reduce juvenile catch.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.371-376
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• 2013

A feeding trial was conducted to determine the optimum dietary protein and lipid levels for the growth of juvenile muddy loach Misgurnus anguillicaudatus. Eight experimental diets (designated as P20L7, P20L14, P30L7, P30L14, P40L7, P40L14, P50L7 and P50L14) were formulated to contain 20%, 30%, 40% and 50% protein with 7% and 14% lipid. Three replicate groups of muddy loach (1.5 g/fish) were fed one of the experimental diets ad libitum for 8 weeks. Survival of fish fed the P20L14 diet was lower than in other groups (P<0.05). Specific growth rate (SGR) and feed efficiency (FE) of fish were affected by dietary protein (P<0.05) and lipid (P<0.005) levels. SGR and FE of fish tended to decrease with increasing dietary lipid level at the same protein level. There were no significant differences in SGR and FE among fish fed diets containing different protein levels ranging from 30% to 50% with the same lipid level. Whole body moisture and lipid contents were affected by dietary protein and lipid levels. Crude lipid content of fish fed the 14% lipid diets was higher than that of fish fed 7% lipid diets at each protein level. The results of this study indicate that a diet containing 30% protein with 7% lipid would be suitable for the optimum growth and effective feed utilization of juvenile muddy loach.