• The Korean Journal of Malacology
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• v.20 no.2
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• pp.111-120
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• 2004

We investigated the reproductive cycle of Corbicula japonica with its gonadal development by histological observations, and the seasonal changes in biochemical mass and foot muscle of the adductor muscle, visceral mass and foot muscle of the clam by biochemical analysis, from January to December, 2003. The reproductive cycle of this species can be classified into five successive stages: early active stage (February to April), late active stage (April to July), ripe stage (June to August), partially spawned stage (July to September) and spent/inactive stage (September to March). According to ANOVA test, there were significant differences (p < 0.05) in total protein, total lipid and glycogen contents among months for all of the visceral mass, adductor muscle and foot muscle. Total protein content was highest in adductor muscle, while lowest in visceral mass. There was no correlation in total protein content between visceral mass and adductor muscle (p = 0.208). However, strong positive correlation was found between adductor muscle and foot muscle (r = 0.769, p < 0.001). In visceral mass, total lipid content was the highest; it was 2 or 3-fold higher than in adductor muscle or foot muscle. The monthly change was also most dynamic in visceral mass. It decreased from January to March (early active stage), and reached maximum in April (late active stage). From May to August (ripe and partially spawned stage), it dradually decreased and then increased again until October (spent/inactive stage). Multiple comparisons showed that total lipid content in visceral mass between all of the adjacent two months was significaltly different (p < 0.05). There were strong negative correlations in total lipid content between visceral mass and adductor muscle (r = 0.687, p < 0.001), and between visceral mass and foot muscle (r = 0.473, p = 0.008). Changes of glycogen content were more or less similar to the changes of lipid contents in visceral mass, adductor muscle and foot muscle, except for April. In April, glycogen content in visceral mass was over four times higher than that in adductor muscle or foot muscle. There was a positive correlation in glycogen content between adductor muscle and foot muscle (r = 0.686, p < 0.001). Especially, total lipid content showed a negative correlation between the adductor muscle and visceral mass. Therefore, these results indicate that the nutrient content of the adductor muscle, visceral muscle and foot muscle changed in response to gonadal energy needs.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.87-94
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• 2011

To find the preliminary environmental conditions for a short-time transport of living olive flounder, Paralichthys olivaceus, the stress response and physiological metabolic activity of the cultured fish to feed deprivation and slow temperature descending ($15.8^{\circ}C{\rightarrow}13.3^{\circ}C$) were monitored for 8 days. The monitored variables were the plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose (GLU), total protein (TP), electrolytes ($Na^+$, $K^+$, $Cl^-$) and thyroid hormones ($TT_4$, $TT_3$, $FT_4$ and $FT_3$). In food deprivation experiment for 8 days, we did not find any statistical change of level in AST, ALT and electrolytes ($Na^+$, $K^+$, $Cl^-$), but found a significant decrease in TP and GLU. In thyroid hormones, the levels of four hormones in plasma were all showing a tendency to decrease. Especially, $FT_4$ and $TT_3$ were significantly decreased, indicating a withering of physiologic activity. In the temperature test, although no any significant change in AST, TP and electrolytes ($Na^+$, $K^+$, $Cl^-$), we observed a significant decrease of ALT and GLU following to temperature descending from $15.8^{\circ}C$ to $13.3^{\circ}C$ (P<0.05). In the levels of thyroid hormones, any significant change was not observed for experimental period. We conclude that the stress response and physiological activity of olive flounder were more influenced by feed deprivation than slow temperature descending at a transport of living fish, and plasma GLU appears to be sensitive factor to physiological metabolic activity, indicating that it could be used as a monitering mark or index for a health inspection of the fish.

• Journal of Aquaculture
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• v.13 no.2
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• pp.129-135
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• 2000

Genetic variabilities of local populations of Anthocidaris crassispina and Hemicentrotus pulcherrimus were analysed by random amplified polymorphic DNA (RAPD) technique with phenotypic variabilities in timing of gonadal maturation, reproductive output and size of individuals in Cheju. H, pulcherrimus, collected from 4 locations during March 1997, indicated that Daepo individuals were significantly smaller than that at Hamdok, Wimi site A and Wimi site B (ANOVA, p>0.001). Gonodal-somatic index (GSI) of the Wimi site B population was significantly higher than that of three other locations (ANOVA, P>0.0001). An ANOVA test conducted on test size of A. crassispina, harvested from six different locations of Cheju during June 1997, indicated that the size of individuals from Pophwan was significantly smaller (P>0.0001) than that from five other locations. GSIs of urchin m Wimi and Hanlim were significantly higher than that from Pohwan and Oedo (ANOVA, p>0.0001). Genetic similarity, calculated from k13 primer analysis of total DNA, among the six different populations of A. crassispina varied from 0.67 to 0.92, and the values for H. pulcherrimus from 0.60 to 0.73; thus there was no genetic variation among different populations of the same species. Therefore, the populations are genetically homologous and the observed phenotypic variabilities were possibly associated with water temperature and food.

• Journal of Aquaculture
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• v.13 no.2
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• pp.169-174
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• 2000

Reproductive cycle of U. unicinctus was studied from September 1998 to August 1999, using gonadosomatic index (CSI) as an indicator. In November, the CSI values were maximum for male (6.2) and female (7.0), respectively; the values were lowest for them (1.0 and 0.5) during the successive february. Subsequently, they rapidly increased and attained peak by March-April. The values decreased again in both sexes and remained unchanged until August. The index increased in October to attain the peak by November. The CSI values clearly indicated that there are two spawning events in a year, namely the first one during April-May and the second one in December. Reproductive cycle was classified into the following successive stages: in female, multipication (January~February, June ~Setember), maturation (March~April, November), spent (May and December), degeneration and resting (June and January), and in male, multiplication January ~ february, June ~September), maturation (March~April, October~November), spent (May and December) and degeneration and resting (January and June). Histological observations revealed that oocytes in the ovary matured simultaneously in November and March. At the same time, the envelopes of matured testis became thinner than those in the early stage.

• Journal of Aquaculture
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• v.17 no.4
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• pp.275-281
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• 2004

The present study was conducted to evaluate dietary requirements for essential fatty acids (EFAs) such as linoleic acid (LA, l8:2n-6), -lenolenic acid (LNA, 18:3n-3), or docosahexaenoic acid (DHA, 22:6n-3), eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (ARA, 20:4n-6) in juvenile eel Anguilla japonica cultured in a recirculating system for 16 weeks. The experimental diets contained 50% crude protein, 10% crude lipid and 3800 kcal/kg energy.Brown fish meal and blood meal were used as the main protein sources, while coconut oil, com oil and linseed oil were used as the lipid source to yield target fatty acids ratios. At the end of the trial, the effects of essential fatty acids supplementation on weight gain (WG), specific growth rate (SGR), feeding efficiency (FE), proximate composition andwhole body fatty acids contents were examined. WG, SGR, and FEof eels fed diet D2, D3, was significantly higher (P<0.05) than those of fish fed the other diets. Whole body HUFA concentration of eels fed D 1 was significantly lower (P<0.05) than those fed the other diets. HUFA/SFA (saturated fatty acids) ratio of whole body in eels fed diets D2, D3 and D6 were significantly higher than that of eels fed diet D1 (P<0.05).DHA/EPA ratio of whole body in eels fed diet D7was significantly higher than those fed the other diets; and eels fed diet D5 showed the lowest DHA/EPA ratio among all the dietary treatments (P<0.05).Based on the experimental results, we concluded that LNA (n-3) and LA (n-6) were necessary for optimum growth of juvenile eel, and the dietary requirement of LNA and LA were 0.35∼0.5% and 0.5∼0.65%, respectively.

• Journal of Aquaculture
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• v.18 no.2
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• pp.122-129
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• 2005

Ammonia is the major limiting factor in intensive aquaculture production systems. Therefore, quantification of ammonia excretion is important for the water quality management in aquaculture systems. Ammonia excretion is known to be affected by many factors such as body weight and dietary protein level (DPL). In this study, experiments were carried out to investigate the effects of body weight and DPLs on the rates of ammonia excretion of Nile tilapia Oreochromis niloticus. Three sizes of fishes (mean initial weight; 4.8 g,42.7 g and 176.8 g) were fed each of two dietary protein levels (30.5% and 35.5%). Daily feeding levels for the three fish sizes of 4.8 g, 42.7 g and 176.8 g were 6%, 3%, and 1.5% body weight per day, respectively. Each group of fish was stocked in a 17.1-L aquarium and all treatments were triplicated. Following feeding, the weight-specific ammonia excretion rate of O. niloticus increased, peaked at 4 to 8 h, and returned to pre-feeding levels within 24 h. Total ammonia nitrogen (TAN) excretion.ate per unit weight decreased with the increase of fish weight for each diet (P<0.05). The TAN excretion rate increased with increasing dietary protein content for each fish size (P<0.05). TAN excretion rates (Y) for each diet with different fish weights were described by the following equations: low DPL diet (30.5%): $Y\;(mg\;kg^{-1}\;d^{-1})=955.69-147.12\;lnX\;(r^2=0.95)$, high DPL diet (35.5%): $Y\;(mg\;kg^{-1}\;d^{-1})=1362.41-209.79\;lnX\;(r^2=0.99)$. Where: X=body weight (g wet wt.). The TAN excretion rates ranged 28.5%-37.1% of the total nitrogen ingested for the low DPL diet (30.5%) and 37.4-38.5% for the high DPL diet (35.5%). Total nitrogen losses of fish fed the high DPL diet $(35.5%;\;0.26\sim0.91g\;kg^{-1}\;d^{-1})$ were higher than those fed the low DPL diet $(30.5%;\;0.22\sim0.68g\;kg^{-1}\;d^{-1})$. The losses decreased per kg of fish as fish size increased. Results will provide valuable information fer water quality management and culture of Nile tilapia in recirculating aquaculture systems.

• Journal of Aquaculture
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• v.18 no.2
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• pp.107-114
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• 2005

Clownfish are important and very popular fish in the ornamental aquarium industry. Demand for the fish is increasing dramatically. The present study was conducted to verify methods of broodstock management, patterns of spawning, rates of egg hatching and estimates of larval growth fur the saddleback clownfish, Amphiprion polymnus. Spawning occurred 8 times between August 2002 to June 2004 with 2 females and 1 male participating. Fertilized eggs were separated by an adhesive matrix and were oval in shape. The eggs were $2.46{\pm}0.13mm$ in size as measured along the longest axis. The percentage of fertilized eggs was 96.7%. Hatching was observed seven days post-spawning and hatching rate was 85.5%. The sizes of the newly-hatched larvae were $4.58{\pm}0.21mm$ TL (total length). Larvae had an open mouth and anus, and an oval yolk sac. At the 1 st day after hatching, the sizes of the larvae were $4.90{\pm}0.35mm$ TL. The larvae began to eat rotifers after complete yolk absorption. On the 5th day post-hatch, larvae were $5.88{\pm}0.31mm$ TL with complete fins and the survival rate was 48.6%. At 8 days after hatching, a band began to appear on head and back of the larvae indicating the beginning of metamorphosis. Metamorphosis was completed at an average TL of $15.00{\pm}2.12mm$ on the 23rd day after hatching. By the 45th day after hatching, juveniles averaged $22.76{\pm}3.22mm$ TL and survival rate was 28.4%.

• Journal of Aquaculture
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• v.21 no.1
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• pp.26-33
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• 2008

This study investigated the synergistic effects of dietary supplementation of quartz porphyry(QP) and a laboratory developed feed stimulants, BAISM(BS) on growth performance and utilization as the additives for juvenile eel Anguilla japonica. Six isoenergetic experimental diets(18.2 kJ/g) were formulated to contain 50% crude protein, 15% lipid with or without dietary QP(Song-Gang stone, Davistone, Korea) and BS supplementation. QP and BS were provided at 0% in the control diet($Q_0B_0$) and at 0.7% QP+0% BS($Q_{0.7}B_0$), 0.7% QP+0.3% BS($Q_{0.7}B_{0.3}$), 0.7% QP+0.5% BS($Q_{0.7}B_{0.5}$), 0.7% QP+0.75% BS($Q_{0.7}B_{0.75}$) and 0.7% QP+1.0% BS($Q_{0.7}B_{1.0}$) in experimental diets on dry matter basis. After four weeks of adaptation, triplicate groups of 30 fish initially averaging $15{\pm}0.1g(mean{\pm}SD)$ were randomly distributed into each aquarium, and they were fed one of the experimental diets for 8 weeks. By the end of the feeding trial, weight gain(%), specific growth rate(%), feed efficiency(%) and protein efficiency ratio of fish fed diet $Q_{0.7}B_{0.5},\;Q_{0.7}B_{0.75}\;and\;Q_{0.7}B_{1.0}$, were significantly higher(P<0.05) than those of fish fed the other diets. But, $Q_{0.7}B_{0.5},\;Q_{0.7}B_{0.75}\;and\;Q_{0.7}B_{1.0}$ were no significant differences(P<0.05). In challenge test, fish were infected by intraperitoneal injection of 0.1 mL bacterial suspension with Edwardsiella tarda per fish after the feeding trial. As a result, fish fed QP and BS supplemented diets have a significantly higher cumulative survival rate than those of fish fed control diet(P<0.05). In conclusion, these results indicated that the optimum dietary supplementation level of QP and BS could be approximately 0.7% quartz porphyry+0.5% BAISM($Q_{0.7}B_{0.5}$) of diet based on WG, FER, SGR, PER, cumulative survival rate in juvenile eel A. japonica.

• Korean Journal of Plant Resources
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• v.25 no.4
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• pp.387-393
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• 2012

In order to improve storability of subtropical yam produced in South Korea, the major pathogens found during the storage were isolated and identified of the pathogenicity, and rot inhibition effect was studied based on the curing treatment condition. Penicillium sclerotigenum and Penicillium polonicum were identified as major pathogens causing rot in subtropical yam during storage, and P. sclerotigenum had stronger pathogenicity. Only the cut surface which has been made during a harvest and has been made smooth before curing generated a normal callus layer. The cut surface of tuberous root was cured in 95% of relativity humidity for three days at $23^{\circ}C$, and cured at $28^{\circ}C$ and $33^{\circ}C$. The observation of callus layer showed that the $23^{\circ}C$ treatment group had similar color saturation between tuberous root and pellicle, while the groups treated above $28^{\circ}C$ showed clear distinction. The generation rate of callus 0.5mm or bigger was 93 percent at $28^{\circ}C$ treatment, 96% at $33^{\circ}C$ treatment, but was 52% at $23^{\circ}C$ treatment. The conventional curing treatment group that used wind or sunlight at room temperature created little callus layer. The infection rate of pathogens according to the relative humidity inside the storage room was low at 40% and 60% of humidity, and the curing treatment period did not make a difference. When the humidity inside the storage room was 80%, all treatment groups rapidly increased the fungal pathogens. The rotten rate of each treatment was studied after 180 days during which the storage temperature was maintained at $16^{\circ}C$ and relative humidity 60%. While the rotten rate of tuberous root that has been cut in conventional curing treatment based on solar and wind was 43%, the one cured at over $28^{\circ}C$ and created the callus layer was less than 18%. While even a healthy tuberous root showed 25% of rotten rate in the traditional treatment group, the one cured at over $28^{\circ}C$ was less than 10%. The weight loss was 1-6% lower in the forced treatment group than in the conventional treatment group.

• Journal of Life Science
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• v.17 no.10
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• pp.1309-1314
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• 2007

Investigation on health conditions of Thai koi (Anabas testudineus) were carried out through clinical and histopathological observations from different farms of Mymensingh district for seven months during August 2006 to February 2007. Fish sampling and water quality parameters (temperature, dissolved oxygen and pH) were monitored on a monthly basis. Clinical examination of fishes was also carried out for any kind of abnormalities at monthly intervals. Samples of skin, muscle, gill, liver and kidney were observed by histological technique. Among the water quality parameters the values of water temperature, dissolved oxygen were found to be at unfavorable level for fish during the colder months in the farms. Clinically it was observed that fishes were more affected from December to January and almost normal in appearance during August to September and February. Different clinical symptoms like scale loss, dermal lesion, ulcer and loss of caudal fin were noticed in December and January. In histopathological study, structures of fish organs were normal from August to September. In the months of October and November, minor pathologies were found to be started. Marked pathological changes like necrosis, pyknosis, inflammation, hemorrhage, hypertrophy, hyperplasia, missing of primary and secondary gill lamellae were observed in the months of December and January. Whereas, in the month of February the pathological condition of fish gradually reduced. Again when considered individual fish farm, fishes of Reliance Aqua Farm were more affected than Sotota Matshya Hatchery. The study showed that severity of clinical and pathological changes were increased in December and January. During the period EUS and protozoan diseases were noticed in A. testudineus of the investigated farms.