• Journal of Aquaculture
• /
• v.20 no.2
• /
• pp.114-120
• /
• 2007

Two feeding experiments were conducted to evaluate the effects of the experimental extruded pellet (EP), commercial EP and raw fish-based moist pellet (MP) on growth of growing flounder (Paralichthys olivaceus). In experiment 1, two replicate groups of the fish (average body weight of $115{\pm}3.2\;g$) were fed one of five experimental diets (EP1-EP5) and MP in circular concrete tanks (4.6 m $\phi$, 0.6 m depth) for 78 days. In experiment 2, in order to evaluate EP in the commercial scale ($8\;m\;{\times}\;8\;m$), flounder (average body weight of $137{\pm}11.4\;g$) were fed one of five EPs (EP1-EP5) used in experiment 1, commercial EP (EP6) and two MEPs (MEP4 and MEP6) as moist pellet types which were made from EP4 and EP6, respectively, by being sprayed with a mixture of water and additives for 80 days. In experiment 1, weight gain of fish fed the all EPs was not significantly different from that of MP. Feed efficiency of fish fed the EP4 was highest, and protein efficiency ratio of fish fed the EP4 and EP5 was significantly higher than that of fish fed the MP (P<0.05). Significant differences were observed in the contents of moisture and crude lipid in the muscle, and moisture in the liver of fish (P<0.05). In experiment 2, weight gain of fish fed the EP4 and MEP4 were highest and feed efficiency showed high tendency in EP4, MEP4 and MEP6. Fish fed the MEP6 showed higher weight gain and feed efficiency compared to those of fish fed the EP6, but there was no difference in those of fish fed EP4 and MEP4. Based on the results of this study, dietary formulations used in EPs could be most recommendable applied in the practical extruded pellet feeds for flounder grown from 114 g to 350 g.

• Korean Journal of Ichthyology
• /
• v.18 no.4
• /
• pp.311-318
• /
• 2006

Ultrastructure of germ cells, the cyst epithelial cells and interstitial cells during spermatogenesis of the stone flounder, Kareius bicoloratus (Pleuronectidae) sampled on the west coast of Korea were investigated by electron microscopic observations. In the primary spermatocyte, the synaptonemal complexes appear in the zygotene stage of the prophase during maturation division. In the growing testis, especially, the interstitial cells (Leydig cells) appear near the primary, secondary spermatocytes and spermatids. Well-developed interstitial cells (steroid hormone secreting cells) which are located in the interlobular space in growing testis have three morphological characteristics of a vesicular nucleus, mitochondria with tubular cristae and smooth endoplasmic reticulum. During spermatogenesis, the primary and secondary spermatocytes attach to the cyst epithelial cell (Sertoli cell) having an elongated ovoid or triangular nucleus and several mitochondria in the cytoplasm. In the growing testis, lipid droplets, the mitochondrial rosettes and glycogen particles appear in the cytoplasm of the cyst epithelial cells near the secondary spermatocytes and spermatids. Particularly, the mitochondria, endoplasmic reticulum, little lipid droplets and the large amount of glycogen particles are present in the cytoplasm of the cyst epithelial cell in the late growing testis. In the late stage of spermiogenesis, the proximal centriole is joined to the nuclear envelope, the distal centriole forms the basal body of the flagellum and gives rise to the axial filament of the flagellum. No acrosome of the sperm is formed as seen in other teleost fish. The head of the spermatozoon is approximately $3{\mu}m$ in length and its tail is about $30{\mu}m$ in length. The axoneme of the tail flagellum of the spermatozoon consists of nine outer doublet microtubules at the periphery and two centrial singlet microtubules at the center. The spermatozoon of this species has two axonemal lateral fins. Especially, the cyst epithelial cells which located near groups of gametes in the various stages, show three functions: nutrition, phagocytosis and steroidogenesis. Especially, the nuclei of cyst epithelial cells in the recovery stage of the testicular developmental stages appear to be irregular in shape after spermiation. Of three functions of the cyst epithelial cell, several characteristics of phagocytosis are showed in the cytoplasm of the cyst epithelial cells in the recovery stage of the testicular developmental stages. At this stage, therefore, it is assumed that the cyst epithelial cells are involved in degeneration and resorption of undischarged germ cells after spermiation.

• Journal of Aquaculture
• /
• v.18 no.4
• /
• pp.225-230
• /
• 2005

This experiment was conducted to compare the effects of extruded pellets and raw fish-based pellet on olive flounder Paralichthys. olivaceus. Six diets were prepared for this study: two formulated extruded pellets (FEP1 & FEP2), three commercially available extruded pellets (CEP1, CEP2 & CEP3) and moist pellet (MP). Weight gain offish fed FEP1 and CEP3 were significantly higher (P<0.05) than those of fish fed FEP2, CEP1, CEP2 and MP, while that of fish fed MP was not significantly different (f<0.05) from those of fish fed the FEP2, CEP1 and CEP2. Feed efficiency of fish fed CEP2 was significantly lower (P<0.05) than those of fish fed FEP1, FEP2, CEP1, CEP3 and MP. There was no significant difference in protein efficiency ratio and hepatosomatic index between fish fed FEP1 and CEP3, and among fish fed FEP2, CEP1 and CEP2. There was no significant difference in condition factor among fish fed the FEP1 and CEP3, and between fish fed FEP2, CTP1 and MP. However, fish fed MP had a lower survival rate than fish fed the other five EP These results suggest that diet FEPl could be developed to replace MP for the owing stage of flounder without adverse effects on growth performance.

• Journal of Aquaculture
• /
• v.19 no.3
• /
• pp.173-177
• /
• 2006

This study was conducted to evaluate extruded pellets (EP) for growth of adult flounder by comparing with raw fish-based moist pellet (MP). Two replicate groups of 150 fish per each tank (initial mean weight 329 g) were fed one of seven EP (EP1, EP2, EP3, EP4, EP5, EP6 and EP7) and a MP for 8 months. Survival of fish fed the MP was not significantly different from that of fish fed the EP1, EP5 and EP7, but significantly higher than that of fish fed the EP2, EP3, EP4 and EP6 (P<0.05). Weight gain of fish fed the MP was significantly lower than that of fish fed the EPI (P<0.05), but not significantly different from that of fish fed EP2, EP3, EP4, EP5, EP6 and EP7. Feed efficiency of fish fed the MP was significantly lower than EP1, EP3, EP4, EP5 and EP6 (P<0.05), but not significantly different from that of fish fed EP2 and EP7 Feed supply (kg/tank) of fish fed the MP was significantly higher than that of fish fed all EP (P<0.05). Condition factor of fish fed the MP was not significantly different from that of fish fed all EP. The contents of moisture, crude protein and lipid in dorsal muscle and whole body was not significantly different among the groups. It is concluded that the dietary formulation used in the EP1, EP3, TP4, EP5 and EP6 can be applied in the practical extruded pellet feeds for adult flounder (329-680g).

• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.550-563
• /
• 2000

This study was carried out in order to elucidate the fundamental data on the taste compounds between wild and cultured fishes produced on Chungmu and Wando at the southern coast areas of Korea. For this purpose, the food components of cultured fishes such as red sea bream Pagnus major, Sebastes pachycephalus and flounder, Paralichthys olivaceus being spot lighted for the main sea fish, the staple food and high economic fish were investigated and compared with those of the wild ones. There was a little appreciable difference in the proximate compositions of all the species from localities between wild and cultured fishes. But according to the growing conditions, wild fishes were higher in moisture contents and lower in crude lipid content than those of cultured fishes and little difference was seen in protein and ash contents between the two. With regard to the nucleotides and their related compounds, i.e. ADP, IMP and inosine were detected but ATP and hypoxanathine were not from them. On the other hand, there were little difference in the total taste compounds of all the species from localities and the growing conditions between wild and cultured fishes. But all the species were higher in IMP content. The total of seventeen amino acids were detected in samples. The highly contents of glutamic acid, lysine, aspartic acid, proline, leucine, alanine, valine and alginine were showed and less low contents of cystein, histidine, methionine, tyrosine and phenylalanine were detected. The total amino acids of the others were much alike in that composition. Little difference was seen from localities and the growing conditions between wild and cultured ones. The free amino acids were much alike in that composition of all the species. There was little difference in the free amino acid compositions all the species from localities and the growing conditions between wild and cultured fishes. But taurine was dominant, showing from 39% to 65% of the free amino acid content and it is followed by hydroxyproline, lysine, alanine and glycine in other. There were differences in the organic acid compositions of all the species from localities and the growing conditions between wild and cultured fishes. In addition, cultured fishes were more abundant in the total organic acid compositions than those of wild ones.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.25 no.3
• /
• pp.197-204
• /
• 1992

A comparative evaluation of water quality in the existing semiclosed fish culture system was made to improve the system management. From the comparison of water quality between the flow-through mode and the recycle mode of the semiclosed system, the malfunctioning of the settling channel deteriorated water quality and reduce the nitrification rate in the recycle mode. The peak concentrations of COD, $PO_4-P$ and SS in the fish tanks appeared just after feeding, and then decreased to normal levels within two hours. However, the $NH_4-N$ concentration increased slightly after two hours of feeding in the recycle mode. The water exchange rate was directly related to the water quality in the semiclosed fish culture system.

• Parasites, Hosts and Diseases
• /
• v.61 no.1
• /
• pp.15-23
• /
• 2023

Concerns about foodborne illnesses caused by Kudoa septempunctata are steadily growing, but reports of K. septempunctata in clinical and food specimens related to food poisoning in Korea are limited. This study aimed to genetically identify K. septempunctata in patients with acute diarrhea and in clinical and food samples related to food poisoning caused by sashimi consumption. Both real-time and nested polymerase chain reaction assays were performed to detect K. septempunctata 18S and 28S rDNA genes in the stools of 348 patients with acute diarrhea, 11 samples (6 stool and 5 rectal swab samples) from patients with food poisoning, and 2 raw Paralichthys olivaceus samples collected from a restaurant where a food poisoning incident occurred. K. septempunctata was identified in 5 clinical specimens (4 stools and 1 rectal swab) and 1 P. olivaceus sashimi sample. All detected K. septempunctata were of genotype ST3. This is the first study to identify K. septempunctata in both patients and food samples with epidemiological relevance in Korea, providing evidence that it is a pathogen that causes food poisoning. Also, this is the first study to confirm the presence of K. septempunctata genes in rectal swabs. Despite continuing suspected occurrences of Kudoa foodborne outbreaks, the rate of identification of K. septempunctata is very low. One reason for this is the limitation in obtaining stool and vomit samples for the diagnosis of Kudoa infection. We strongly suggest the inclusion of rectal swabs among the diagnostic specimens for Kudoa food poisoning.