• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.332-341
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• 1989

Stomach contents and microstructures in otolith of Chaenogobius laevis were analyzed for the determination of age, growth and food. By comparaing structural similarity in a series of growth increments from three samples collected in a two-week interval, daily deposition of growth increments in otolith can be validated. Growth in length as daily basis was well represented by Gompertz curve: $L= 5.73{\cdot}\;e^{15.06}(1-e^{-0.0015t})$ for the fish age of $46\~102$ days. Mean growth rate increased from 0.40 mm/day for the age of $50\~60$ days to 0.85 mm/day for the age of $80\~100$ days. Chasnobius laevis showed a carnivorous feeding behavior and its major food items were polychaetes, amphipods and copepods. Small individuals ($15\~30$ mm SL) preyed heavily on copepods as well as polychaetes. However, the portion of copepods in stomach contents was decreased with increasing fish siEe, and this decrease was compensated by an increased consumption of amphipods.

• Journal of fish pathology
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• v.8 no.1
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• pp.57-67
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• 1995

Twenty-four hours, acute toxicity and the histopathological effect of formaline to flounder, Paralichthys olivaceus larvae were examined. The $LC_{50}$ values obtained to farmaline were 2,520 ppm in 1 hour treatment. 1.610 ppm in 2 hours treatment, 868 ppm in 4 hours treatment and 141 ppm in 24 hours treatment. Many pathological features such as hypertrophy of mucous and epithelial cells in secondary gill lamella, hyaline droplet degeneration of tubular epithelial cells in the proximal convoluted segment of renal tubules, focal or massive necrosis in liver cells and pycnotic nucleus in heart cells were recognized. The above results were discussed in relation to the application of formaline as therapeutic agent in flounder disease.

• Journal of fish pathology
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• v.14 no.1
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• pp.11-15
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• 2001

For the production of healthy shrimp(Penaeus chinensis, Penaeus japonicus) seedlings free from the white spot baculovirus(WSBV), we tried to disinfect shrimp eggs with iodine. A relative hatching rate of over 50% has resulted from the treatments of fertilized eggs of fresh shrimps(P. chinensis) with an effective povidon-iodine concentration of 20-200 ppm for 30 seconds and 60 seconds, respectively. The 60 sec treatment group with a 20 ppm effective povidon-iodine concentration showed nearly a 50% relative hatching rate. The over 50 ppm treatment group, however, did not result in hatching show a relative hatching rate. These hatching rates were similar to those in the fertilized eggs of kuruma prawns treated with povidon-iodine solutions. In case of washing fertilized eggs with UV-irradiated seawater 33.3% relative hatching rate in fresh shrimps was much lower than 55.2% in kuruma shrimps. Treatment fertilized eggs of 2 species of shrimp with 200 ppm iodine for 30 sec did not affect the survival rate of the larvae until the early stage of the post larvae even though the hatching rates were low. In order to produce healthy shrimp seedlings non-infected by WSBV, the shrimp eggs should be washed with UV-irradated seawater and sterilized with a low povidon-iodine concentration for a short time.

• Development and Reproduction
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• v.18 no.3
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• pp.139-143
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• 2014

Different with other fishes, the guppies (Poecilia reticulata) is ovoviviparity, which retain their fertilized eggs within the follicle throughout gestation. The synchronously growing diplotene oocytes store nutrients in droplets and yolk, before their maturation and fertilization. The lecithotrophic strategy of development entails the provisioning of embryos with resources from the maternal yolk deposit rather than from a placenta, it allows the extracorporeal culture of guppy embryo. Studies on their early development of live bearers like the guppy including lineage tracing and genetic manipulations, have been limited. Therefore, to optimize conditions of embryo in vitro culture, explanted embryos from pregnant females were incubated in embryo medium (L-15 medium, supplemented with 5, 10, 15, 20% fetal bovine serum, respectively). We investigated whether the contents of FBS in vitro culture medium impact the development of embryos, and whether they would hatch in vitro. Our study found that in 5% of FBS of the medium, although embryos developed significantly slower in vitro than in the ovary, it was impossible to exactly quantify the developmental delay in culture, due to the obvious spread in developmental stage within each batch of eggs, and embryos can only be maintained until the early-eyed. And although in culture with 20% FBS the embryos can sustain rapid development of early stage, but cannot be cultured for the entire period of their embryonic development and ultimately died. In the medium with 10% and 15% FBS, the embryos seems well developed, even some can continue to grow after follicle ruptures until it can be fed. We also observed that embryonic in these two culture conditions were significantly different in development speed, in 15% it is faster than 10%. But 10% FBS appears to be more optimizing condition than 15% one on development process of embryos and survival rate to larvae stage.

• Ocean and Polar Research
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• v.27 no.4
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• pp.463-476
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• 2005

Mesozooplankton samples were collected to investigate the spatial distribution in the Chuuk lagoon of the Federated States of Micronesia through three surveys from 2002 to 2004. Average temperature was $28.70^{\circ}C$ in August 2002, $30.17^{\circ}C$ in October 2003 and $29.18^{\circ}C$ in July 2004 at a water depth of 2rn. Average salinity was 33.95 psu in August 2002, 33.56 psu in October 2003 and 33.77 psu in July 2004. Total rnosozooplankton consisted of 70 taxa during the study period, among which copepods were the most diverse group. Foraminiferans, radiolarians, copepods and appendicularians, which comprised about 70% of total zooplankton abundance, were important components in the zooplankton community. Within the copepod group, Acartia spp., Centropages spp. and Undinula spp. were dominant in August 2002, Acartia spp., Centropages spp., and Oithona spp. in October 2003, and Acartia spp., Undinula spp., and Oithona spp. in July 2004. Total zooplankton abundance was high around Weno Island, while low in stations located in the northern part of Weno Island. High abundances of appendicularians were found in the southern part of weno Island as well as around Weno Island. Appendicularians foraminiferans, radiolarians, Sagitta spp. and immature copepods accounted for most of the distribution pattern of the mesozzoplankton community throughout the study area. These results suggest that appendicularians may be potential food items for fish larvae around Weno Island in the Chuuk lagoon states.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.606-613
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• 2003

This study investigated the effects of food type (condensed freshwater Chlorella, dried Chlorella, dried Spirulina, dried Schizochytrium, baker's yeast and $\omega-yeast$) and amount, and supplementation of vitamin $B_{12}$ on the growth of freshwater rotifer (Brachionus calyciflorus) in high density culture. Growth of rotifers fed condensed freshwater Chlorella was the highest and its density ranged $7.65-8.14{\times}10^3\;inds./mL.$ The primary lipid acids of rotifers fed condensed freshwater Chloyella were linoleic and linolenic, and their amount ($\%$ of total fatty acids) were $48.8\%\;and\;26.8\%,$ respectively. This suggests that condensed freshwater Chlorella would be an effective diet for high quality and quantity rotifers, which in turn serve as live food for freshwater fish larvae. Growth rate of rotifers with Chlorella supplementation increased as amount of supplementation increased up to 1.5 and 2.5 mg at 28 and $32^{\circ}C$, respectively. However, undissolved ammonia toxicity and packing volume of Chlorella in culture medium, reached the optimal conditions for the stable and effective cultivation of rotifers when amount of condensed freshwater Chlorella was 1.5 mg in dry weight per 1,000 rotifers at $28^{\circ}C\;and\;32^{\circ}C$ Growth of rotifers in condensed freshwater Chlorella with vitamin $B_{12}$ supplementation was significantly higher than that of rotifers without supplementation. However, no significant difference was found among the different concentrations of vitamin $B_{12}.$ Therefore, vitamin $B_{12}$ could improve the growth of rotifers (B. calyciflorus).

• Journal of Aquaculture
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• v.1 no.2
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• pp.135-143
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• 1988

Rotifers became an important live food for fish larvae, especially for marine fishes, and Chlorella has been used as a very useful food for the mass culture of rotifer. However, not many tests for suitable Chorella species for the mass culture of rotifer were done and many of Chlorella sp. have been used without consideration of species for this purpose. There-fore, two species of marine Chlorella and four species of freshwater Chlorella were tested to select suitable species for the mass culture of a rotifer, Brachionus plicatilis. These Chlorella species were cultured in five different culture media; f/2, Erdschreiber, Complesal for marine species and S$\cdot$K, Wai and Complesal for freshwater species. Proximate analyses were done to see the protein, lipid and ash contents of a marine species, C. ellipsoidea and a freshwater species, C. vulgaris. Amino acids content of these species were also tested. C. ellipsoidea and C. vulgaris showed better growth than the other species. For marine Chlorella sp., f/2 media was better than Erdschreiber and Complesal. But for the freshwater species, Complesal showed the best result in growth. By the proximate analyses, C. ellipsoidea has higher lipid contents whereas C. vulgaris has higher protein and ash. In the analysis of amino acid of Chlorella, it was remarkable that freshwater Chlorella, C. vulgaris, has high content of $NH_3$ comparing with marine Chlorella, C, ellipsoidea. According to the above results, C. vulgaris seems have higher possibilities for mass culture of rotifer but further studies are needed.

• Korean Journal of Ichthyology
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• v.10 no.2
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• pp.207-215
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• 1998

Just after hatching the embryo has a yolk sac and straighted digestive tract. Just after parturition in 5.0mm TL the mouth and anus were opened. In the larval stage of 5.2mm TL, digestive tract could be divided into pharynx, esophagus, stomach, pyloric caeca and intestine of the early differentiated state. The esophagus of larvae in 5.3mm TL has a PAS positive mucous cell. From over 5.7mm TL, PAS positive goblet cell recognized in the intestine. PAS positive absorptive cell began to appear in the intestine from 5.9mm TL. Yolky materials were absorbed completely in 6.0mm TL. In the larvae of B.5mm TL, gastric glands were observed in the mucosa, but the surface epithelium did not have PAS positive granules. From over 9.0mm TL, the histological structure of esophagus showed similar to adult. In the juvenile stage from 13.0mm to 15.0mm TL, histological structure of the stomach, pyloric caeca and intestine showed similar to adult. From the ultrastructural and histochemical study, it is concluded that the functional digestive tract is present in the juvenile stage from 18.0mm to 20.0mm TL.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.32-40
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• 2017

Samples were obtained from broodstok in May, 2010, while naturally fertilized embryos were maintained, and the process of skeletal development was observed from larvae and juvenile. Prelarvae immediately after hatching showed an average total length of $6.85{\pm}0.63mm$ (n =5), Premaxillary and dentary were ossified, parasphenoid was ossified in the cranium, and centrum and caudal bone did not ossify. Prelarvae showed ossification with maxillary, articular, and epihyal, and branchiostegal rays of hyoid arch were ossified at 2 to 3 days after hatching with an average total length of $7.25{\pm}0.28mm$ (n=5). The vertebrae began to ossify in the direction of the tail, and neural spine began to ossify above the ossified vertebra. Postlarvae showed ossification of lateral ethmoid, alisphenoid, parietal, and caudal skeleton in the cranium when the average total length was $9.00{\pm}1.53mm$ (n=5) in 6 days after hatching. At 40 days after hatching, postlarvae ossified maxillary in the cranium, and ossified endopterygoid and ectopterygoid, etc. in the palate, when the average length of $23.3{\pm}0.28mm$ (n=5). At 120 days after hatching, with the average length was $37.5{\pm}2.83mm$ (n=5), caudal skeleton had one additional epural bone ossification, resulting in ossification of a total of 3 epural bone to complete ossification of all spicules.

• Journal of Aquaculture
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• v.7 no.4
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• pp.189-205
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• 1994

Formerly, adult-tiger puffer, Takifugu rubripes with ova caught in the sea, were used for seedling production. But it was difficult to secure naturally-ripened adults. For the purpose of adult tiger puffer in captivity, this study was carried out. To determine the growth 220 tiger puffers hatched in 1990 (3-year-old) and 1991 (2-year-old) were used. For spawning and egg incubation leading to fry development, eggs were stripped from tiger puffers hatched in 1988 (5-year-old) and 1990 (3-year-old) through human chorionic gonadotropin (BCG) treatments. In May, 1993, mean body length and mean body weight of 2-year-old tiger puffer were $30.72\pm1.35cm\;and\;1,048\pm228 g,$ and that of 3-year-old tiger puffers were $36.02\pm1.17cm$ and $1,402\pm66g$ respectively. The relationship between body length (L) and body weight (W) of 2-year-old the tiger puffers during the experiment period was represented as $W\;=\;1.7892L^{31524}\times10^5$ (r= 0.9436) and that of 3-year-old, $W=\;3.2840L^{36099}\times10^6$ (r= 0.9070) respectively. The GSI in female 2-year-old-fish changed from $0.23\times0.l2\;to\;0.74\pm0.08$, during the experiment period, and in male it didn't change remarkably until November, but thereafter it increased and showed a peak of $8.69\pm5.09$. The GSI of 3-year-old-fish showed a peak of $8.05\pm5.58$ in April in female and $12.65\pm4.60$ in May in male. The change of HSI in 3-year-old-fish was correlative to the change of GSI, but in 2-year-old-fish it was little correlative. In female gonad of 2-year-old tiger puffer, the mature oocytes reached $350{\mu}m$ in April, but thereafter they didn't spawn and became atrophied. But in male gonad, a great number of spermatozoa were crowded in the testicular lobuli in April. Female gonad of 3-year-old tiger puffer had the mature oocytes of 650 pm in March and the ripe oocytes, $900{\mu}m$ in April. Male testis development was similar to that of 2-year-old-fish. Egg-stripping after hormone treatments was possible past 139 hours and 142 hours from each of two 5-year-old-fish (500IU/kg, BW), and after 114 hour from a 3-year-old-fish (1,000 IU/kg, BW) under water temperature $16.3\~17.8^{\circ}C$. Eggs stripped amounted was 650 g and 400 g from two 5-year-old-fish and 610 g from the 3-year-old-fish, and fertilization rates were $98.0\%,\;97.4\%\;and\;96.5\%$ respectively. All the hatched larvae devloped into normal fry.