• Journal of fish pathology
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• v.18 no.2
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• pp.157-165
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• 2005

A new disease causing mass mortality of farmed snakehead (Channa arga) has emerged in Korea over the summer of 2005. The affected fish showed no specific external signs with the exception of a distended abdomen and hemorrhaging around the anus. After opening the abdomen, the visceral organs, liver, spleen and kidney, present numerous white nodular structures. Histopathological examination revealed these nodules to be evidence of granulomas in the visceral organs. A Gram-positive, filamentous bacterium was isolated from all of the affected fish. Development of primers for a genus-specific peR assay for Nocardia, following analysis of the sequences of the complete 16S rRNA genes from Nocardia spp. and non-Nocardia bacterial genes, allowed identification of the causative organism as Nocardia. This is the first report of a nocardial infection of fish in Korea.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.119-120
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• 2003

우리나라에 분포하는 모자반류는 모두 28종으로 알려져 있으며 (이와 강 2002) 이 가운데 식용으로 이용되는 것은 모자반 (S. fulvellum)이 대표적이다. 모자반의 양식은 주로 서남해 지역에서 이루어지고 있으며 이들의 종묘생산은 자연에서 생식기탁이 성숙되는 4-5월경에 이루어지는데, 유배의 대량 방출을 위한 성숙 모조의 다량 확보가 어렵고 일시에 유배의 대량 방출을 유도하기 위한 성숙 유도 기법의 연구는 전무한 실정이다. 따라서 이 연구에서는 모조의 실내 배양을 통하여 유배의 대량 방출을 위한 성숙 유도 기법과 배양 조건별 엽체의 성숙 및 난방출율을 구하여 모자반의 조기채묘에 유용한 자료로 사용하고자 하였다. 또한 채묘된 발아체의 초기생장에 필요한 최적 배양 환경을 구명하고자 하였다. 모자반 모조는 전남 진도군 조도 지역의 수심 3-5m에서 채집하였으며, 채집 즉시 실험실로 운반하여 유수식 사육 수조에 수용하였다. 성숙 유도는 20$\ell$ 플라스틱 bottle을 사용하였으며, 성숙률의 정량화를 위하여 암생식기탁을 절단하여 수차례 멸균해수에서 세척후 멸균된 5cm직경의 petri dish에 멸균해수20$m\ell$와 함께 수용하여 Multi-chamber incubator에서 배양하였다. 배양조건은 5개 온도조건 (5, 10, 15, 20, $25^{\circ}C$)과16:8h의 장일 광주기 조건으로하였으며 조도는 80 $\mu$molm$^{-2}$ s$^{-1}$로 하였다. 모든 실험구는 3반복 실험하였으며 2일 간격으로 생식기탁의 생장 및 성숙 그리고 난방출 여부를 현미경하에서 측정하였다. 난이 방출된 모조로부터 유배를 분리하여 3개 조도 구간 (30, 60, 100 $\mu$molm$^{-2}$ s$^{-1}$)과 5개 온도 구간 (5, 10, 15, 20, $25^{\circ}C$)의 조합인 15개 배양 조건하에서 엽체의 길이생장을 측정하였다. 생식기탁으로부터 난의 방출은 15$^{\circ}C$와 2$0^{\circ}C$ 조건에서 배양 2일후부터 방출되기 시작하였으며, 배양 9일후 2$0^{\circ}C$ 조건에서 가장 높은 96.7$\pm$5.8%의 난방출율을 보였다. 또한 15$^{\circ}C$ 조건에서는 배양 9일후 76.7%의 난방출율을 보였다. 1$0^{\circ}C$와 $25^{\circ}C$ 조건에서는 배양 11일까지 36.7%의 난방출율을 나타내어 온도 조건에 따라 난방출 비율에 차이를 보였다. 따라서 이러한 실내 배양 결과를 다량의 모조를 조기에 성숙시키기 위해 모조 수용 수조의 수온을 자연수온보다 2~5$^{\circ}C$ 높은 12~15$^{\circ}C$ 조건으로 유지하여 15일간의 수조 관리 후 모조의 대량 유배 방출을 유도할 수 있었다. 모조 성숙을 위한 사육 수조의 수온을 2$0^{\circ}C$ 이상으로 가온할 경우 엽체의 끝녹음을 유발하였으며 가온에 따르는 가온 비용이 수반되므로 엽체의 난방출율이 70% 이상에 도달하는 15$^{\circ}C$ 조건으로 유지하는 것이 경제적일 뿐만 아니라 엽체의 건전도 유지에도 바람직하였다. 유배의 초기생장은1$0^{\circ}C$와15$^{\circ}C$의 온도조건에서 길이생장이 빠르게 증가하여, 배양 35일 후 15$^{\circ}C$와 60 $\mu$molm$^{-2}$ s$^{-1}$의 조건에서 3.9$\pm$0.2mm로 가장 높은 값을 나타내었다. 엽체의 초기 길이생장은 15$^{\circ}C$, 60 $\mu$molm$^{-2}$ -s$^{-1}$의 조도 조건에서 가장 우세하였으며, 다음으로 30과 100 $\mu$molm$^{-2}$ s$^{-1}$의 조건 순으로 나타났다. 2$0^{\circ}C$와 $25^{\circ}C$의 온도 조건에서는 각각 1.8~2.1mm로 길이생장에 있어 유의한 차이가 없는 것으로 나타났다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.87-91
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• 1969

Experiments on the rearing of larvae of the prawn, Penaeus japonicus Bate, have been con-ducted by using a large tank A ($3.4\times1.9\times1.0m$) and two small tanks B and C ($1.45\times0.85\times1.0$). 1) Between spawning and the first zoeal stages, no significant elapsed time difference was noticed among the rearing tanks. At about $23^{\circ}C$ of water temperature nearly all of the larvae in the tanks metamorphosed into the first zoeal stage in about 36-48 hours. However the period of time which elapsed between the spawning and post-larval stage showed some differences bet-ween the tanks, i.e., 19-20 days in tank A and 15-17 days in tanks B and C, respectively 2) No difference in body length of the larvae has been observed among the three tanks. 3) The post-larva passed through several molts, one every four or five days, before reaching the young prawn about 36-40 days after spawning. 4) Throughout the zoeal stages the highest mortality was found at the time of molting between the first and second zoeal stages showing about $51.39\%$ in tank A, $50.70\%\;and\;31.91\%$ in tanks B and C, respectively. 5) Total mortality during the duration of the larval stages was around $75\%$ in all the rearing tanks.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.381-387
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• 2019

From 2017 to 2019, the ovipositional and the developmental characteristics of Gampsocleis ussuriensis Adelung in the Buan area of Jeonbuk Province were examined. G. ussuriensis were mostly found in the weeded areas around the reservoir, where the adults first appeared in mid-July, showed up where by the early September, and overwintered in eggs. Nymphs appeared in early April to mid-July the next year. The nymphs hatched from early April and adults appeared after molting five times. The ovipositional period of G. ussuriensis was approximately 58 days. The total number of eggs per female was 124. The mean longevity of adults was 95.6 days for females and 84.8 days for males. Ovipositional mats were best with mixed Masato and Coco-Pitt at a ratio of 7:3. Developmental period of G. ussuriensis nymphs was 64.1 days at 24℃ and was longer than at different temperatures. The higher the temperature, the shorter the developmental period. The survival rate of nymphs was the best at 32℃ in 77.8%. The higher the density while rearing, the lower the survival rate, and the faster the development and molting velocity.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.367-373
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• 2014

In order to investigate the impact of recycling agricultural wastes as feed for mealworm (Tenebrio molitor), we evaluated the replacing effect by the different level of tangerine shell, Chinese cabbage, king oyster mushroom (Pleurotus eryngii) and Enoki mushroom (Flammulina velutipes) substrates on wheat bran feed. Larval survival rate, larval weight, developmental period of larva, pupation rate and pupal weight were evaluated. In tangerine shell and Chinese cabbage replacement group, no replacing effects found. In all groups replacing by spent King oyster mushroom (Pleurotus eryngii) substrate, survival rate of larva was similar to that of control group but larvae weighed less than control group significantly. Developmental period of larva increases in the group of King oyster mushroom substrate replacement. Larval and pupal weight in Enoki mushroom (Flammulina velutipes) substrate by the level of 40 and 50%, replacement effect showed best results in successive breeding considering pupation rate. It is concluded that replacing 40 and 50% of Enoki mushroom (Flammulina velutipes) substrate is appropriate to substituted diet of Tenebrio molitor larvae.

• Journal of fish pathology
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• v.19 no.1
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• pp.65-72
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• 2006

Nervous necrosis virus (NNV) that causes severe mortality during seed production of red drum (Sciaenops ocellatus) is known to be vertically transmitted from infected spawners. This study was conducted to produce NNV free seeds by testing spawners for NNV infection and using virus free eggs for seed production. RT-PCR analysis of 40 spawners showed 18 positives and 22 negatives. NNV was not detected from eggs obtained from the negative spawners but was detected from those obtained from the positives. NNV was not detected from culturing seawater in tanks and Chlorella spp., Brachionus plicatilis., and Brine shrimp those were provided as live feed. The survival rates of fry from NNV positive and negative spawners were 80% and 85%, respectively by two weeks after hatching. The mortality increased from 25days after hatching and the final survival rate of seeds from NNV positive and negative spawners were 0% and 18.3%, respectively on 41 days after hatching. These results suggested that virus free red drum seeds can be obtained by using virus-free spawners.

• Journal of fish pathology
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• v.13 no.1
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• pp.21-29
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• 2000

A new nutritional disease has occurred among the hatchery-reared Korean bullhead fingerlings (Pseudobagrus fulvidraco) in the Chonbuk Province in September 1997. Diseased fish were all dead within 3-7 days, showing sluggish behavior, head up and tail down swimming. Most characteristic clinical signs were anaemia, clubbed and fused gill, skin desquamation. haemorrhage around the mouth and at the base of pectoral fins. Any causative bacteria and parasites were not isolated from the lesions and internal organs of the diseased fish. The hepatosomatic index, red blood cell count, hematocrit, hemoglobin and erythrocytes size of peripheral blood in the diseased fish were remarkably decreased compared with those of normal fish. In the histopathological observations, epithelial hyperplasia of the gill filaments initiated at the base of the gill was pronounced. This symptom was the characteristic appearence of all the diseased fish. A 0.6% saline bath and feeding a pantothenic acid-supplemented diet were conducted to decrease the mortality. Ten days after 0.6% saline bath or 25 days after feeding a pantothenic acid supplemented diet resulted in decreasing in the mortality. Microscopic appereance of the gill from the recovered fish was similar to that of the gill from healthy fish. These results indicate that the disease was caused by deficency of pantothenic acid in their diet and that 0.6% saline bath or supplementation of pantothenic acid in the diet was an effective way to decrease the mortality.

• Journal of Life Science
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• v.27 no.10
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• pp.1185-1190
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• 2017

Insects are gaining recognition as an alternative source of protein. As a result, more and more domestic farms have begun mass rearing of edible insects. In order to produce high quality insects, studies on the development of safe and nutritious feed sources are needed. Given the cost of rearing insects, agricultural and industrial by-products are good sources for feed. The efficient utilization of these by-products can help in reducing the cost of production and preventing environmental pollution. In the current study, Citrus unshiu peel (CP), soybean curd cake (SCC), soybean oil meal (SOM), and brewers dried grain (BDG) were investigated for their effects on larval growth and development of Protaetia brevitarsis. Interestingly, the feed with 10% SCC increased larval weight by 3.5 times. For the larval period, the group of 10% SCC was significantly shorter than the control. Furthermore, minerals such as Zn, Ca, K, Mg, Na, and P were recorded to be high in 10% SCC. A total of 17 amino acids were present in 10% SCC, of which tyrosine and arginine were predominant. The heavy metal contents were very small amounts or not detected in any of the investigated groups. These findings provided a scientific basis for the utilization of soybean curd cake as a nutritional feed source to promote larval growth and produce quality insects.

• 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 applied entomology
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• v.59 no.2
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• pp.133-138
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• 2020

In 2016, the two-spotted cricket was approved as a general food ingredient by the Korean Ministry of Food and Drug Safety. Additionally, the two-spotted crickets have high protein content (60%) and can be reared throughout the year even during the overwintering period. In this study, storage conditions were set in case cricket breeding was not possible due to problems such as breeding space and labor costs, and selection oviposition mats to determine high fecundity rates and low cannibalism rates for the eggs were investigated. The oviposition mat was mostly composed of soil (p < 0.05). Less than 62 crickets per 10 litters were found to be best suited for 1 day of spawning, based on the cannibalism rate of the eggs during the egg laying period. The results from the hatched eggs indicated that the hatching extended 12 to 14 days, and the best hatching rate was approximately 85% when stored at low temperatures(16℃) for 10 days. An efficient production proposed method that established the best oviposition mat and egg storage method for the cricket.