• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.3
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• pp.300-308
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• 2023

This study aimed to evaluate the utilization of low fish meal (LFM) diet and black soldier fly (BSF) Hermetia illucens meal supplementation in LFM diet as a fish meal (FM) replacer or functional additive for juvenile olive flounder Paralichthys olivaceus. Three LFM diets were prepared to contain 30, 25, and 20% FM, respectively (designated as F30, F25, and F20). Three BSF diets were prepared by adding 2.0, 2.5, and 3.0% BSF in the LFM diets, respectively (designated as F30B2.0, F25B2.5, and F20B3.0). A total of 540 fish (initial mean body weight: 22.3±0.01g) were randomly distributed into 18 tanks (240 L) in triplicate groups and fed the experimental diets twice daily for 12 weeks. Results showed that there were no significant differences in the growth performance, feed utilization and survival among all the groups. Lysozyme activity significantly increased in F30B2.0 and F25B2.5 groups compared to their respective LFM groups. Total immunoglobulin was significantly higher in F30 group than in F20 group. Anti-protease and myeloperoxidase activities were significantly higher in F30B2.0 group than in F20 group. Innate immunity gradually decreased with decreasing FM level in all the groups. BSF supplementation significantly improved immunity compared to their respective LFM diets. Therefore, BSF could be used as an immuno-stimulant supplement in LFM diets for P. olivaceus.

• Korean Journal of Environmental Biology
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• v.21 no.1
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• pp.36-41
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• 2003

In order to estimate chornic toxicity of copper in the juvenile oliver flounder, Paralichthys olivaceus, experiments were investigated the effects of long term sublethal copper exposure on survival rate, metabolic rate, feed efficiency and growth rate. Oliver flounder were exposed for 6 weeks to four different sublethal copper concentration (50, 80, 180, 320 $\mu\textrm{g}$ $L^{-1}$). Survival rate of them significantly affected above 180 $\mu\textrm{g}$ $L^{-1}$, and reduced for increase exposure periods and concentrations. Copper exposure to 180 and 320 $\mu\textrm{g}$ $L^{-1}$ significantly decreased metabolic rate in olive flounder. Exposure to waterborne copper concentrations as high as 80 $\mu\textrm{g}$ $L^{-1}$ resulted in significantly reduced feed efficiency and growth rate. From these results, it could be concluded that the high level of 80 $\mu\textrm{g}$ $L^{-1}$ copper concentration in the bottom water would curtail production of the olive flounder in coastal area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.39-43
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• 2003

Experiments were carried out to investigate the effects of long term sub-lethal cadmium exposure on survival, growth and metabolic rate of olive flounder, Paralichthys olivaceus for 6 weeks. Survival rate of the flounder was significantly affected above $980{\mu}g/L$. Growth rates of the flounder exposed to ${\geq}210\;{\mu}g/L$ of cadmium concentration were significantly decreased than that exposed to normal condition, Metabolic rate in the cadmium concentration ${\geq}210\;{\mu}g/L$ was significantly reduced with increasing cadmium concentration than that in normal condition. This study revealed that high cadmium concentration $$({\geq}210\;{\mu}g/L$$ reduced growth and metabolic rate of the juvenile flounder suggesting potential influence on the natural mortality of olive flounder in the coastal areas.

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.4
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• pp.562-567
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• 2009

This study was conducted to evaluate of improving extruded pellet (EP) for growth of juvenile flounder by comparing with raw fish-based moist pellet (MP) diet. Two replicate groups of 80 fish per each tank (initial weight of $36.0{\pm}1.2 g$) were fed one of the three EPs (EP1, EP2 and CEP) and (MP for 16 weeks. Survival was not significantly affected by experimental diets (P>0.05). Weight gain of fish fed the MP was not significantly different from that of fish fed the EP1 & EP2 (P>0.05), but that of fish fed CEP was significantly lower than that of fish fed MP (P<0.05). Specific growth rate of fish fed the CEP was significantly lower than those of fish fed EP1, EP2 and MP (P<0.05). Feed efficiency of fish fed the EP1 was significantly higher than those of fish fed CEP and MP (P<0.05), but not significantly different from those of fish fed EP2 (P>0.05). The Contents of crude protein and crude lipid in whole body were significantly different among all groups (P<0.05). Therefore, these results strongly suggest that EP1 & EP2 diets could be developed to replace MP diet for flounder without adverse effects on growth performance.

• Journal of Aquaculture
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• v.16 no.2
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• pp.104-109
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• 2003

The present study aims to evaluate protein and phosphorus availabilities of five different dietary protein sources during the 6-week feeding trial in juvenile olive flounder, Paralichthys olivaceus as determined by growth performance and phosphorus retention. Five diets containing blood meal (BM), poultry by-product (PBP), squid liver powder (SLP), feather meal (FM) and soybean meal (SM) were prepared by mixing a basal diet (BD) with one of five test ingredients at the ratio of 7 to 3. As a reference diet, BD contains three different protein sources such as white fish meal, casein and gelatin. After 2 weeks of the conditioning period, fish initially averaging 2.7$\pm$0.02g (mean$\pm$SD) were randomly distributed into each aquarium as a group of 30 fish reared in the recirculating system. Fish of triplicate groups were fed one of six experimental diets (BD+five test diet). After 6-week feeding trial, pro- tein efficency ratio (PER) of fish fed BM diet was the lowest in experiment groups. While fish fed PBP diet showed a significant higher PER as compared to the FM diet, and fish fed SLP diet and BD were a higher PER than did fish fed PBP diet. However, there was no significant difference in PER among fish fed SLP diet, BD and SM diet, and between SM diet and PBP diet. Phosphorus retention efficiency of bone (PR $E_{b}$) of fish fed BM diet was the lowest in all the diets, and fish fed FM diet showed a higher PE $R_{b}$ than fish fed BD and SM diet. However, there was no significant difference in PER among fish fed FM diet, SLP diet and PBP diet, and among SLP diet, PBP diet, SM diet and BD. These results indicate that SLP could be a suitable protein source for low pollution diets of olive flounder in the future fish feeds market. Furthermore, PBP and SM are available protein source to reduce P waste in the oliver flounder aquaculture with the use of proper mixture of other protein sources and more processing to improve protein availibility of these.ese.

• Development and Reproduction
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• v.17 no.4
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• pp.321-327
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• 2013

The innate immune system is the only defense weapon that invertebrates have, and it is the fundamental defense mechanism for fish. The innate immune response is important in newly hatched flounders because it is closely involved in the initial feeding phase, which is why it is essential for survival during the juvenile period. The expression analysis of genes involved in the innate immune response in the olive flounder (Paralichthys olivaceus) in the days after hatching is incomplete. Therefore, we have begun to examine the expression patterns of genes specifically induced during the development of the innate immune system in newly hatched flounders. Microscopic observation showed that pronephron formation corresponded with the expression of perforin-encoding gene. These results suggest that perforin plays a vital role in the innate immunity of the kidney during developmental stages. Perforin expression was strong at the start of the development of the innate immune response, and continued throughout all the development stages. Our findings have important implications with respect to perforin's biological role and the evolution of the first defense mechanisms in olive flounder. Further studies are required to elucidate the perforin-mediated innate immunity response and to decipher the functional role of perforin in developmental stages.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.3
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• pp.553-563
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• 2013

This study was conducted to evaluate the quality characteristics (proximate composition, fatty acids, amino acids and sensory properties) of whole body and dorsal muscle in olive flounder, which is switch size from juvenile to growing fed extruded pellets (EP) and raw fish-based moist pellet (MP) for 9 months. Sample was collected at 5 and 9 months to compare with those of EP and MP. Whole body crude protein of fish fed EP at 9 months was significantly higher than that of fish fed MP (P<0.05). Linolenic acid(18:3) and n-6/n-3 ratio in dorsal muscle of fish fed EP were significantly higher than those of fish fed MP (P<0.05). No significant differences were observed in the results of the flavor, color, taste and texture of the muscle of the fish fed EP compared to those fed MP (P>0.05). Based on the experimental results, we concluded that olive flounder cultured with EP is not inferior to those fed MP for quality characteristics of whole body and muscle.

• Fisheries and Aquatic Sciences
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• v.20 no.9
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• pp.20.1-20.8
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• 2017

The objective of this study was to examine the effect of dietary supplementation of taurine for juvenile olive flounder (Paralichthys olivaceus) at low water temperature ($16.4{\pm}0.36^{\circ}C$). Fish meal (FM)-based diet was used as the control diet. Four other experimental diets were prepared by adding taurine to FM-based diet at 0.25, 0.50, 1.00, and 1. 50% (T1, T2, T3, and T4, respectively). Each experimental diet was fed to triplicate groups of fish (initial mean body weight, 19.5 g) for 10 weeks. At the end of the feeding trial, growth performance and feed utilization, hematological parameters, non-specific immune responses, whole-body proximate composition, and liver mRNA expression of insulin-like growth factor-1 (IGF-1) were investigated. Feed conversion ratio was significantly reduced while protein efficiency ratio was significantly increased in taurine-supplemented groups. Hematocrit and hemoglobin were also significantly increased while plasma cholesterol levels were decreased in taurine-supplemented groups than those in the control group. Nitroblue-tetrazolium, myeloperoxidase and lysozyme activities, and plasma immunoglobulin level were significantly increased by taurine supplementation. These results suggest that dietary taurine supplementation is effective in improving growth performances, feed utilization, and innate immunity of olive flounder in low water temperature season.

• Journal of fish pathology
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• v.34 no.2
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• pp.255-259
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• 2021

This is the first report describing acute mass mortality occurred in juvenile olive flounder (Paralichthys olivaceus) caused by gas bubble disease (GBD). A total of 610 fish (average weight = 35 g), which were more than half of the fish acclimated at 17℃ in an aquarium, were killed within two days of acclimation. The dead and moribund fish showed excessively opened opercula and mouths, and occasionally, severe exophthalmia. Through microscopic observation, numerous gas emboli were found in the gills of the dead and live fish, while the fish were not infected with any microbial pathogens. The dissolved oxygen (DO) saturation level of the rearing water and seawater nearby the facility reached 145% and 286%, respectively, whereas other water quality parameters (such as salinity, pH, and chemical oxygen demand) were normal. The extreme saturation rate of seawater in the shore nearby seemed to be due to an enormous algal bloom that occurred there. Through molecular identification based on 18S rDNA sequences, the most dominant algal species was most closely related to Ulva californica (99.87% sequence identity) followed by U. prolifera, U. linza, and U. curvata (99.81%). Therefore, it can be concluded that supersaturated seawater due to mass algal bloom caused gas bubble disease in the olive flounder, leading to mass mortality. After technical adjustment, such as increased aeration, lowered water circulation rate, and inlet water filtration using micro-pore carbon filters, the DO level became normal, no further mortality occurred and the status of the fish was stabilized.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.43-48
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• 2019

This study was conducted to investigate the effect of extruded pellet (EP) size on the growth performance of olive flounder Paralichthys olivaceus at the juvenile (Exp-I; $62.2{\pm}0.05$), growing (Exp-II; $150{\pm}1$) and sub-adult (Exp-III; $299{\pm}1$) stages. In Exp-I (3, 4, 5 and 6 mm diets), Exp-II (4, 9, 11 and 13 mm diets) and Exp-III (9, 11, 13 and 16 mm diets), triplicate groups of fish were fed four EP diets of different pellet sizes. In Exp-I, larger pellet sizes were significantly better than the smallest pellet size (3 mm). In Exp-II, significantly improved feed and protein efficiency were observed with increasing pellet size. The feed conversion ratios of the fish fed the 4 and 9 mm diets were significantly lower than those of fish fed 11 and 13 mm diets. The dietary digestibility of protein and energy was higher in smaller EPs than in larger sizes. In Exp-III, the growth performance of fish was not affected by the pellet size. However, feed intake was significantly affected, increasing with increasing pellet size. Therefore, the optimum pellet sizes for olive flounder under the conditions in this study were 5 mm for 60-150 g fish and 9 mm for 150-500 g fish.