• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.490-498
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• 2011

Two consecutive feeding trials investigated the effects of feeding rate and pellet expansion by water-soaking on the growth performance, blood components and histology of olive flounder Paralichthys olivaceus. The first two experiments were carried out to determine the effects of pellet expansion and feeding rate. In the first experiment, growth performance, feed utilization and survival of fish were not significantly affected by pellet expansion for six weeks. There were no significant differences in hematocrit, hemoglobin, aspartate aminotransferase, alanine aminotransferase, glucose and total protein of fish fed the expanded pellet. However, whole-body lipid content of fish in the non-expanded group was significantly higher than that in the expanded group. Histological analysis of the anterior intestine revealed that fish in the expanded group had shorter and smaller mucous folds. These results indicate that pellet expansion had no beneficial effect in terms of growth performance, feed utilization and fish health. In the second experiment, weight gain and feed efficiency were significantly increased as feeding rate increased from 0 to 2.5% body weight per day (BW/d), but there were no significant differences in weight gain or feeding efficiency in fish fed the expanded pellet at ratios of 2.5% BW/d and satiation for three weeks. Plasma aspartate aminotransferase activity of fish fed the expanded pellet at a ratio of 2.5% was significantly lower than that of starved fish. Histological analysis of the anterior intestine revealed that fish in the 0% group had shorter mucous folds. Broken-line regression analysis suggested that the optimum juvenile olive flounder feeding rate was 3.5% BW/d during the low temperature season ($16-17^{\circ}C$).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.429-436
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• 2017

The seasonal and interannual variations in fish assemblages in the coastal waters off Gijang were examined with an otter trawl from 2015 to 2016. A total of 59 fish species was collected during the study period. The dominant species were Caelorinchus multispinulosus, Clupea pallasii pallasii and Chelidonichthys spinosus. Seasonal changes in fish assemblages appeared to be distinct in the study area. The fish assemblages in summer and autumn were clearly distinguishable from those in other seasons, and the largest numbers of species and individuals were captured in winter and summer, respectively. Because fish assemblages are closely related to changes in water temperature, long-term changes in water temperature can have a significant impact on the productivity of offshore fisheries by changing fish species composition, habitat migration, and growth rate of fish.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.4
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• pp.521-526
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• 1993

Two percent of monocalcuim phosphate (MCP) was added to control diet consisted of fish meal (18%), soybean meal (36%) and wheat flour (37%) in order to examine the effects on phosphorus (P) discharge and growth of carp (Cyprinus carpio). Growth trial, during which digestibility measurements were made over 7 days, was conducted for 4 weeks using a recirculated rearing system with a settling column for feces collection. Fishes (initial body weight of about 200 g) were fed five times a day upto satiation with tank controlled at $24-26^{\circ}C$. Fishes fed the diet containing 2% MCP (MCP-2) showed about two-fold improvement on both growth rate and feed utilization, compared to those of fishes fed the control diet; weight gain (129 g vs 62 g), feed conversion ratio (1.20 vs 2.46), protein efficiency ratio (2.09 vs 1.07) and daily growth index (3.70 vs 1.93). However, feed intakes were maintained at the same level (150 g/fish) between the two treatments. Dry matter digestibilities of two diets were relatively low, which were 58 and 60% for respective control and MCP-2 diets due to low digestibility of total carbohydrates. However, the digestibilities of both dietary protein (85%) and lipid (90%) of diets were relatively high. While all the P fed were observed to be discharged from fish fed control diet, the discharge from fish fed the MCP-2 diet was decreased up to less than the half (34.9 g/kg wt. gain) of the control. These present results revealed that the supplementation of dietary P requirement by MCP can not only promote growth performances but also reduce the level of P loading to water which is the primary water pollution indicator.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.247-255
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• 2019

This study was conducted to investigate the effects of extrusion pressure and particle size of feed ingredients on the growth performance and plasma hormone activity in juvenile olive flounder Paralichthys olivaceus. Experimental diets were prepared with extrusion pressure manipulated by screw speed [low pressure (LP), 885 rpm/min; high pressure (HP), 708 rpm/min] and different dietary particle sizes [specific surface area: small (SS), $169.9m^2/kg$; large (LS), $67.4m^2/kg$] in a two-level factorial design. Four experimental diets (LP+SS, LP+LS, HP+SS, and HP+LS) were randomly assigned to 12 tanks (3 replicates) stocked with 20 fish (initial weight, 57 g) per tank. After a 4-week feeding trial, the observable trends of the main effects of extrusion pressure and particle size on growth performance showed that LP and SS enhanced fish weight gain. The plasma insulin-like growth factor-I level was significantly higher in fish fed the LP+SS diet than in fish fed the HP+SS diet. These results indicate that manipulation of the physical qualities of feed through adjustment of extrusion pressure and feed ingredient particle size may influence the growth performance of juvenile olive flounder, which should be considered in feed manufacture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.3
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• pp.319-327
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• 2022

An eight-week feeding trial was conducted to evaluate the effects of a diet consisting of different onion juice processing by-product (OJPB) levels on juvenile black rockfish Sebastes schlegelii growth, feed utilization, and, lysozyme and antioxidant enzymes activities. Juvenile rockfish (2.2 g) were randomly distributed into 15 flow-through tanks (30 fish/tank). Five experimental diets were prepared in triplicate. The experimental diets were supplemented with OJPB at different levels of 0 (control), 0.25, 0.5, 0.75 and 1% (designated as OJPB0, OJPB0.25, OJPB0.5, OJPB0.75 and OJPB1, respectively). At the end of the feeding trial, the results revealed that the fish that were fed the OJPB0.75 and OJPB1 diets showed enhancement in growth (weight gain and specific growth rate) and feed utilization (feed efficiency and protein efficiency ratio) compared with the fish that were fed other diets. Plasma lysozyme, glutathione concentration, and superoxide dismutase and catalase activities significantly increased in the fish that were fed the OJPB0.75 and OJPB1 diets. In conclusion, dietary supplementation of 0.75-1% OJPB in juvenile rockfish diet improved the growth performance and antioxidant status.

• Journal of Aquaculture
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• v.21 no.2
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• pp.102-106
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• 2008

This study was conducted to evaluate extruded pellets(EP) for the growth of sub-adult flounder Paralichthys olivaceus by comparing with raw fish-based moist pellet(MP). Two replicate groups of 150 fish per each tank(initial mean weight $594{\pm}6.5g$) were fed one of two EPs(EP1 and EP2) and a MP for 32 weeks. Survival was not significantly affected by experimental diets. Final mean weight of fish fed the EP1 was not significantly different from that of fish fed the MP, but that of fish fed EP2 was significantly lower than that of fish fed EP1 and MP (P<0.05). Feed efficiency and protein efficiency ratio of fish fed the EP1 and EP2 were significantly higher than those of fish fed MP(P<0.05). Daily feed intake of fish fed the EPs was significantly lower than that of fish fed MP(P<0.05). Condition factor was not significantly different among all groups. The contents of moisture, crude protein and lipid in dorsal muscle were significantly affected by experimental diets(P<0.05). Based on the results of this study, the dietary formulations used in EP1 and EP2 could be applied in the practical extruded pellet feeds for sub-adult flounder(594-1,126 g).

• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.300-307
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• 2010

This study examined the effects of the dietary inclusion of various concentrations of red ginseng byproduct (RB) and a mixture containing red ginseng byproduct, garlic extract, yeast and filler (CR) on the growth, body composition, serum chemistry, and lysozyme activity of juvenile olive flounder (Paralichthys olivaceus). Juvenile fish (n= 630) weighing 5.0 g were randomly distributed into 21 180 L flow-through tanks (30 fish/tank). Seven experimental diets were prepared in triplicate: a control diet without additive, and diets containing 0.5, 1 and 2% concentrations of RB (RB-0.5, RB-1, RB-2) and CR (CR-0.5, CR-1, CR-2) at the expense of wheat flour. After an 8-week feeding trial, serum chemistry and lysozyme activity of fish were measured. Mean weight gain was significantly higher in fish fed the control diet than in fish fed the RB and CR diets. The dietary inclusion of RB and CR reduced feed utilization. Mean serum glucose and triglyceride (TG) levels were higher in fish fed the control diet than in fish fed the other diets. Mean glutamate pyruvate transaminase (GPT) levels of fish fed the control and RB-2 diets were higher than those of fish fed the RB-0.5, RB-1, CR-1, and CR-2 diets. Mean lysozyme activity levels of fish fed the RB-0.5 and RB-1 diets were higher than those of fish fed the control and CR diets. The results of this study indicate that red ginseng byproduct may be utilized as an immunostimulant rather than as a growth promoter for juvenile olive flounder. Dietary inclusion of 0.5% red ginseng byproduct effectively improved serum glucose, GPT, TG, and lysozyme activity of the fish in this study.

• Fisheries and Aquatic Sciences
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• v.19 no.8
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• pp.32.1-32.6
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• 2016

A feeding trial was conducted to evaluate the effects of two different sizes of extruded pellets (EP) ($EP_1$ - 3 mm or $EP_2$ - 5 mm) and a moist pellet (MP) in olive flounder, Paralichthys olivaceus, reared in semi-recirculation system. A total of 450 fish with an average initial weight of $5.0{\pm}0.2g$ (mean ${\pm}$ SD) were fed one of the three experimental diets in triplicate groups. At the end of a 6-week feeding trial, weight gain, specific growth rate, and feed efficiency of fish fed EP diets were significantly higher than those of fish fed MP (P < 0.05). Water quality parameters like turbidity, total ammonia nitrogen, and total phosphorous from tanks of fish fed $EP_1$ and $EP_2$ were significantly lower than those from tanks of fish fed MP. Blood plasma glutamic oxaloacetic transaminase and glucose concentration were significantly higher in fish fed MP diet compared to fish fed EP diets (P < 0.05). Whole body crude protein contents in fish fed EP diets were higher than those from the fish fed MP diet. Whole body amino acid content like threonine, aspartic acid, serine, tyrosine, and cystine were found to be significantly higher in fish fed EP diets than those in fish fed MP diet. In considering overall performance of olive flounder, $EP_2$ diet could be recommended for the successful aquaculture of this important fish species.

• Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.7.1-7.8
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• 2020

Background: To minimize the use of antibiotics and to obtain a more sustainable fish culture and aquaculture industry, development of alternative natural source of immunostimulant to replace antibiotic in aquafeed is highly needed. Objective: Dietary inclusion effect of yacon (YC), ginger (GG), and blueberry (BB) on growth, body composition, and disease resistance of black rockfish against Vibrio anguillarum was compared to ethoxyquin (EQ). Methods: Four hundred eighty juvenile (an initial weight of 4.2 g) fish were randomly distributed into 12 of 50 L flowthrough tanks (forty fish per tank). Four experimental diets were prepared; the control (Con) diet with 0.01% EQ inclusion, and YC, GG, and BB diets at 1% each additive inclusion. Each additive was included into the experimental diets at the expense of wheat flour. Each diet was assigned to triplicate tanks of fish and hand-fed to satiation twice daily for 8 weeks. At the end of 8-week feeding trial, 20 fish from each tank fish were artificially infected by intraperitoneal injection with 0.1 mL of culture suspension of pathogenic V. anguillarum containing 3.3 × 10⁶ cfu/mL respectively. Fish were monitored for the following 8 days after V. anguillarum infection and dead fish were removed every 6 h for the first 4 days and 12 h for the rest of the study. Results: Weight gain, specific growth rate (SGR), and feed efficiency ratio (FER) of fish fed the YC diet was higher than those of fish fed all other diets. However, feed consumption, protein efficiency ratio, and protein retention was not affected by dietary additive. Moisture, crude protein, and crude lipid content of the whole body of fish were affected by dietary additive. Analysis of the Kaplan-Meier survival curves showed that survival of fish fed the YC, BB, and GG diets was higher than the Con diet. Conclusion: Oral administration of YC can improve not only weight gain, SGR, and FER of black rockfish, but lower mortality of rockfish at occurrence of V. anguillarum.

• Ocean and Polar Research
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• v.23 no.3
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.