• Journal of Aquaculture
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• v.10 no.4
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• pp.473-483
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• 1997

Yolk resorotion and commencement of external feeding in larvae of red spotted grouper, Epinepheus akaara were studied to understand the high mortality of larvae. Consumption of yolk was higher than that of oil globule for the first 24hs after hatching. The resorption rates of yolk and oil globule increased with the increase of temperature. The time yolk was comsumed up to 99% was 84hs after hatching in 23~$25^{\circ}C$,72hs at ~$27^{\circ}C$, and 60hs in 29~~$31^{\circ}C$, while the time for oil globule was 96hs in 23~$25^{\circ}C$, 84hs at $27^{\circ}C$, and 60hs in 29~$31^{\circ}C$. The relationship between mouth openning time (Y) and water temperature (X) was repersented as a linear regression, Y=-2.53X+118.4, (r2=0.89). In 72~96hs after hatching, upper jaw sizes of the larvae reached around 0.114 mm. By the time the larvae comsumed most of the yolk and oil globule, and started external feeding. The relationship between upper jaw length (Y) and total length (X) was represented as a linear regression, Y=0.139X-0.165, (r2=0.88). Rotifer was not found in the guts of larvae before 72hs after hatching at $28^{\circ}C$, when larvae resorbed their yolk and oil globule over 99%. But, at 96hs after hatching, about 33% of the larvae had the rotifer in their guts. Delayed feeding experiments revealed that the earlier food supply within 84hs after hatching showed the better survival rates for the larvae. The larvae fed at 96hs after hatching died all within 120hs.

• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.9-17
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• 2018

This study investigated how the larvae of three winter-spawning fishes are adapted in a cold water environment by examining the morphology, digestive system, and swimming ability of larvae from three winter-spawning species (Gadus macrocephalus, Liparis tanakae, Hexagrammos agrammus). Data were collected at hatching and first feeding. The results were compared with repored data on several non-winter-spawning species. Mean total lengths at hatching (${\pm}SD$) were $4.35{\pm}0.11mm$, $5.26{\pm}0.08mm$, and $7.48{\pm}0.35mm$ for G. macrocephalus, L. tanakae, and H. agrammus, respectively. Three winter-spawning fishes had well-developed digestive tracts after hatching than those of non-winter-spawning fish larvae. Yolks were intact until 5 days post-hatching in all three species, indicating that they had longer mixed-feeding periods compared with fishes spawned during other seasons. G. macrocephalus, L. tanakae, and H. agrammus larvae had superior cruise and burst speeds (measures of swimming ability) than non-winter-spawning larvae. We conclude that the unique characteristics of these three winter-spawning species are naturally selected adaptations under lower water temperature in winter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.4
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• pp.233-250
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• 1970

The present paper deals with the results of the observations on the characteristics of the eggs being ripen by injection of synahorin and the larvae of the black porgy. Mylio macrocehalus (Basilewsky). The adult fish used in the experiments, during May 11th to June 5th, 1970, were obtained from a fish-farm of the Atsumi Fish Culture Company in Aichi Prefecture, Japan, The results obtained are as follows: 1. The egg is colorless and buoyant, spherical in shape, measuring from $0.81\~0.96\;mm$ in dia-meter with a single oil globule, measuring $0.20\~0.23\;mm$. 2. Hatching took place within about 35 hours and 50 minutes after insemination of eggs at the water temperature $19.6\~22.5^{\circ}C$ (Mean, $20.6^{\circ}$). 3. The newly hatched larvae were 1.57 mm in total length, with the oil globule situated at the posterior part of the elongated oval-shaped yolk sac. Melanophores and xanthophores were distributed on the middle of the caudal region, and were scattered on the surface of the oil globule, but none on the yolk sac. 4. The diameter of the eggs ill each adult is distinguished into two types, large and small. The former is in the range of $0.811\~0.873\;mm$, the latter is $0.874\~0.963\;mm$. 3. The hatching rate of black porgy was in the range of $78.63\~95.19\%$ in large and $68.84\~74.80\%$ in small eggs. The mean hatching rate of total eggs was $79.80\%$. 6. The optimum temperature of hatching black porgy is in the range of $20\~26^{\circ}C$. The highest temperature limit of hatching the black porgy is from $26.71\~28.56^{\circ}C$. 7. The total length of hatched larvae is not maintained pararell to diameter of eggs and total length of the large larvae is from $1.976\~2.225mm$, and that of small larvae is $1.526\~1.90mm$. 8. The diameter of yolk sac of black porgy is in the range of $0.878\~0.979\;mm$ 9. The initial survived larva of the black porgy was $13.71\%$ in minimum, and $79\%$ in maximam. And the mean initial survived rate was $48.3\%$. 10. In conclusion, the biological characteristics of hatched larva of black porgy is seemed to be possible for large scale production of artificial seedlings. But experimental results make initial food the prime object believed to be supplemented.

• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.208-214
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• 2000

The egg development and morphological changes of larvae of the file fish, Thamnaconus modestus(Gunther), was investigated by artificial insemination. The fertilized egg was spherical in shape, colorless and adhesive with 0.63~0.67mm in diameter and yolk had 20~30 oil globules of various size (0.04~0.16 mm in diameter). The hatching occured at 53 hours after fertilization in $21.0\sim23.0^{\circ}C$ of water temperature. Hatched larvae measured 2.07~2.20 mm in total length with 5~6+17~18=22~24 myotomes. The 3~4 days after hatching larvae grew to the total length 2.62~2.77 mm, opened mouth and anus. The 5 days after hatching, total length of the larvae was 2.74~3.04 mm, the first dorsal fin was formed at the behind of head. After hatching 12~13 days larvae attained 3.78~3.99 mm in total length. This period formed rudimental dorsal fin and anal fin. Twenty days after hatching, larvae grew to 6.04~6.17mm in total length, at which time the dorsal, anal and caudal fin rays reached 19~20, 18~19 and 9~10, respectively.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.66-66
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• 2003

대구는 한대성 어종으로 크기가 1m에 달하는 대형 고급 어종이나 최근 자원량 감소로 인하여 생산량이 급격히 줄어들었다. 대구 자원 증대를 위한 방류 사업은 1981년부터 국립수산과학원 주도로 실시되어 오다가 현재는 수협과 경남도 등에서 수정란을 연안에 뿌리는 방식으로 추진되고 있다. 그러나 지금까지 노력에도 불구하고 방류를 통한 자원 증대 효과는 극히 미진한 것으로 알려져 있어 대구 차원의 실질적 증대를 위해서는 생존율 향상에 도움이 되는 종묘생산에 의한 치어의 방류가 절실히 요구된다. 본 연구에서는 대구의 종묘생산을 위한 생물학적 기초자료를 얻기 위하여 채란, 부화 및 자어사육 결과를 보고한다. 강원연안 대구의 채란은 1월 중순부터 3월 초순까지 가능하였으며, 산란기 암수 GSI는 암컷 33.5, 수컷 13.7이었다. 전장 80.4cm 암컷의 포란수는 363만 개였으며, 복부압박법으로 180만개의 알을 채란할 수 있었다. 채란된 알은 직경 1.08mm의 원형 점착란으로, 습식 인공수정 방법에 의한 수정률은 65%이 었다. 부화는 1시간 이상 세란 후 가두리에서 부화시키는 방법이 효과적이었으며, 수온 4$^{\circ}C$에서는 10일 후 배체형성 후 폐사하였으나, 7$^{\circ}C$에서는 수정 12일 후 65.0%가 부화하여 가장 양호하였다. 1$0^{\circ}C$에서는 수정 8일 후에 30%의 부화율을 보였으며, 13$^{\circ}C$와 16$^{\circ}C$에서는 각각 4일 및 2일 후 발생이 중지되고 폐사하였다. 부화자어는 전장 4.3mm였으며, 부화 45일째 9.3mm로 성장하였다.

• Korean Journal of Ichthyology
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• v.1 no.1_2
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• pp.73-82
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• 1989

The development of eggs and larvae, and minute scale-like tubercles on the skin surface of the larval Acanthorthodeus asmussi from Korea were observed in the laboratory. The egg was nearly ovoid-shaped. The number of egg averaged 195 per an oviposition. The morphological character of larval development was relatively similar to those of Acheilognathus tabira tabira, A. tabira subsp. (a), A. yamatsutae, A. moriokae, A. cyanostigma and A. rhombeus. The larvae of this species had many scale-like tubercles ellipsoided in a diagonal cross section on the skin surface of the body. And also this species moved like incessant wiggly movement pattern as that of fly maggot duing the larval development. As regards the tubercles and larval movement pattern, the larvae of A. asmussi shared similar characters with those of Acheilognathus rhombeus, A. longipinnis and Pseudoperilampus typos. Hence A. asmussi may be closely related to these species. The latter three species are autumn-spawning bitterlings and the larval development always retard in a certain stage, while A. asmussi is a spring-summer spawning species and the larval development never retards. Judging from these facts, it should be considered that there are close relations in evolutionary trend between the two spawning species.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.9-18
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• 2016

Histological and morphological development of the digestive tract of sevenband grouper were observed from after hatching to 60 days. Fishes were fed with rotifer (Brachionus rotundiformis) and chlorella (Chlorella ellipsoidea) after hatching from 2 to 20 days rotifer and brine shrimp (Artemia salina) in after 20 days rotifer, brine shrimp and semi-dry artificial diet in after 23 days. Histological and morphological development of ten larvae was observed by paraffin embedding method after fixing in 10% neutral buffered formalin. Sevenband grouper RLG showed characteristics of carnivorous fish by average 0.87. Larvae after hatching can't open the mouth and anus digestive tract was observed in a straight line following yolk sac. Larvae was observed feeding activity by opening the mouth and anus. Metamorphosis started 8 days after hatching. Esophagus divided four layer, and goblet cell was observed in esophagus, mid intestine and rectum. Larvae started cannibalism and it was caused by difference of growth. The inside of stomach was differentiated to cardiac orifice, body of stomach, pyloric stomach, and pyloric caeca. Goblet cell was observed all intestine. Gastric gland differentiated after hatching 28 days in stomach. Secretion of gastric juice was found at stomach and mucosal fold pyloric caeca. Even thought the inside of stomach expended and the number of gastric gland increased consistently and goblet cell in intestine and mucosa became longer, histochemical changes follow couldn't be found during transforming juveniles 38 days after hatching.

• Korean Journal of Ichthyology
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• v.4 no.1
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• pp.20-28
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• 1992

The influence of starvation on morphological change and survival rate of the left eye flounder larvae was examined at the KORDI laboratories in March, 1990. 1. The larvae of left eye flounder began of feed on rotifers in 5 days after hatching. In case of non-feeding, all of the larvae died in 11 days after hatching. The larvae which fed 1 day after the normal first feeding schedule grew normally but 100 of the larvae died in 14 days when the feeding was delayed for 2 days after hatching. 2. With the exhaustion of the yolk, the total length, body length, myotome height and gut height of unfed larvae decreased. Gut height is the most decreased demensions while starving. 3. The ratio of gut height to myotome height in unfed larvae has declined most rapidly compare to other demensions during the starvation. At 13 days after hatching, the ratios of these between fed and unfed larvae were 0.797 and 0.467, respectively. 4. The morphology of starving larvae were characterized as sharpened jaw, projected edge of lawer part of clavicle and slender gut.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.317-331
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• 1989

Chaenogobius laevis inhabit brackish waters. Adult male protects egg mass laid under the stones. The egg with small oil globule varied from 3.40 to 4.04 mm in diameter. When water temperature is $22.0\~23.0^{\circ}C$, larvae hatched about 113 hours after fertilization. The newly hatched larvae reared for 33 days grow up to 12.10 mm in total length and developed to the jevenile. When larvae length attained about 8.0 mm, jaw bones were more rapidly ossified than vertebrae and cranium.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.458-464
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• 1993

From November 1992 to January 1993, the rockfish, Sebastes inermis was reared in the laboratory, and observed the developmental stage of the eggs and larvae squeezed from the parent fish. On December 4 1992, developing eggs at morula stage were obtained from female parent fishes($17.4{\sim}20.3mm$ in total lenght(TL)). The diameter of eggs ranged from 1.20 to 1.35mm(n=50), and oil globules in white color were found in the eggs. Hatching began about 55 hours after morula stage at the water temperature of $9.2{\sim}12.3^{\circ}C$. The newly hatched larvae measured from 2.90 to 3.35mm in TL with $8+12{\sim}13=20{\sim}21$ myomeres. Total lengths of the larvae will be from 5.75 to 6.15mm in 27 and 30 days after the hatching, respectively. Myomere number was $8+17{\sim}18=26$.