• Development and Reproduction
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• v.18 no.3
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• pp.173-178
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• 2014

In order to monitor the developmental features of embryos, larvae, and juveniles of Oryzias latipes (Temminck and Schlegel), Oryzias latipes was caught in river of Shinduck-dong, Yeosu-si, Jeollanam-do, on May 2011, and experiments were carried out in Ichthyology laboratory at Chonnam National University. The blastodisc step was the first level for natural spawning. The optic vesicle, Kupffer's vesicle, myotome began to appear 75 hours 57 minutes later. After blastodisc development, the pectoral fins were made at 143 hours 37 minutes and the tail was separated started at the same time. Hatching was observed at 167 hours 27 minutes after blastodisc. The total length of the hatched larvae was 4.95~5.10 mm (mean, 5.01 mm), the mouth and anus were opened. Larvae used yolk completely after 3 days after hatching. The total length larvae was 5.45~5.56 mm (mean, 5.52 mm) after 8 days after hatching, and appeared the stems for tail. The stems pectoral, anal fin were showed after 14 days and the stems dorsal, ventral fin were appeared after 19 days. For 35 days after hatching, the total length of larvae 13.95~15.30 mm (mean, 14.64 mm), and at this time, fins and body were transferred like the adult Oryzias latipes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.287-295
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• 2017

Egg development and morphological change of larvae of the Sakhalin sole Limanda sakhalinensis were studied by observing specimens obtained in a rearing experiment from fertilized eggs to the juvenile stage. The wild broodstock was collected in January 2010 and kept in a circular water tank (${\O}1.5{\times}1m$) at a temperature of $14.5{\pm}0.5^{\circ}C$. Fertilized eggs ranged from 0.72 to 0.82 mm ($0.77{\pm}0.07mm$, $mean{\pm}SD$) in diameter. The eggs were spherical, transparent and adhesive demersal. The egg yolk was divided from the oocyte 10 min after fertilization (AF), and an embryo was formed in 36 h AF. More than 50% of the eggs hatched within 133 h AF. The mouth and anus did not open until $3.5{\pm}0.25mm$ total length (TL). At 4, days after hatching (AH), the fish became larvae 3.7 to 4.2 mm ($4.0{\pm}0.36mm\;TL$), yolk absorption was completed and the mouth began to open. The left eye moved upward and the nostril moved to the right at 39 days AH. These post-larvae ranged from 8.0 to 9.9 mm TL ($8.9{\pm}1.33mm\;TL$). At 50 days AH, the fish became juveniles ($12.4{\pm}1.20mm\;TL$) There were 70-72 dorsal fin rays, 55-56 anal fin rays, 11 pectoral fin rays, and 6 ventral fin rays and the juveniles adopted a benthic life.

• Journal of fish pathology
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• v.16 no.1
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• pp.13-21
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• 2003

The infection characteristics with scuticociliates at on-land rearing farms and hatcheries of flounder, Paralithys olivaceus was investigated during the year of 2001 by juvenile infection routes. When culture tanks for living food organisms such as chlorella, rotifer, and Artemia were searched, scuticocilates were detected both in live and dead rotifer, and at the dregs of culture tank bottoms at almost hatcheries. When rotifer infected with scuticocilates fed on fish larvae, lots of scuticocilate were inhabited at the bottom of fry rearing tanks. After feeding on scuticocilates-infected rotifer on fish larvae, first infection was detected at 10 days after bottom dwelling or 40 days old after hatching. By histopathological examination we confirmed the infection route of eyeball or brain contamination was that the ciliate worms digged through mouth and front part of the dosal fin cuticle, transferred into eyeball along the epithelium and muscle tissue, and reached finally into brain by the muscle and nerve tissue. The infection of internal organs was clarified into two routes. The first route was started from the infection at ventral and anal fin rays by the worms, and reached at the anus and rectum through the epithelium and muscle tissue. The second route was initiated from the infection at urinary organ and reached into the rectum epithelium cells, inner wall of intestine, abdominal cavity, pancreas, kidney, and pancreas. At seed production farms where fish larvae fed on scuticocilate-free rotifer, the worms were not detected not only at the food organisms culture tanks and juvenile rearing tanks but also larval flounder less than 7cm in total length.

• Journal of Aquaculture
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• v.9 no.1
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• pp.11-18
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• 1996

We described morphological characteristics of embryonic, larval, and juvenile period of the yellow puffer, Takifugu obscurus. We defined seven periods of embryogenesis the zygote, cleavage, blastula, gastrula, segmentation, pharygula, and hatching periods. The eggs were adhesive and spherical in shape. The egg yolk had numerous tiny oil globules. Hatching began about 280 hours after insemination at $17.0{\pm}1.0^{\circ}C$ water temperature. Melanopores of star shape were seen on yolk, head and trunk during the pharygula and hatching period. The hatched larvae haying large yolk were $3.00\~3.54$ mm in size with $25\~26$ myomeres. The larvae completely absorbed the yolk materials and oil globules within 7 days after hatching and became post-larvae. Laval fish became juveniles within 60 days after hatching, and they reached $23.54\~30.12$ mm in total length and had fin-rays.

• Korean Journal of Ichthyology
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• v.35 no.1
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• pp.10-19
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• 2023

This study aimed to examine the early life history of Trident goby (Tridentiger brevispinis) by observing their egg development and juvenile fish morphology. The average size of mature eggs was 1.13~1.41 (1.30±0.07) mm (n=30), and 0.70~0.86 (0.79±0.04) mm (n=30) in long diameter and short diameter, respectively. The incubation period at 24±1℃ ranged from 167~228 h. The newly hatched larvae measured 2.31~2.78 (2.51±0.18) mm (n=30) in total length (TL), and their mouth and anus were not yet open. At 3 days after hatching, the preflexion larvae reached 2.84~3.10 (2.98±0.10) mm in TL, where in their yolk absorption was complete and their mouths began to open. At 19 days after hatching, the larvae reached the flexion stage, measuring 4.02~4.62 (4.36±0.19) mm in TL. The tip of their notochord was bent upward. At 30 days post-hatching, the larvae reached the postflexion stage, measuring between 5.04~6.36 (5.76±0.51) mm in TL, with the tip of the caudal fin bent at 45°. After 54 days, the larvae had reached the juvenile stage, measuring between 7.43~9.84 (8.48±0.90) mm in TL, and were differentiated by their constant number of fins (6 first dorsal, 12 second dorsal, 11 anal, and 10 ventral fins). This study found that T. brevispinis had larger fertilized eggs and a greater number of myotomes in hatching larva than similar species. Additionally, the distribution of melanophores in T. brevispinis was distinct from that in other similar species, making it easy to distinguish them morphologically.

• Korean Journal of Ichthyology
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• v.35 no.2
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• pp.83-90
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• 2023

Five days after hatching in Konosirus punctatus, the larvae were 5.86~6.21 mm (mean 5.96 mm) in TL and ossified parasphenoid, prefrontal, premaxillary, dentary. Sixteen days after hatching, the larvae were 9.66~10.18 mm (mean 9.96 mm) in TL and ossified prootic, opisthotic, ectopterygoid, and epihyal. Twenty-five days after hatching, the larvae were 11.02~12.64 mm (mean 11.03 mm) in TL and ossified supraclavicle, posttemporal, four actinost. Twenty-eight days after hatching, the larvae were 11.98~12.81 mm (mean 12.34 mm) in TL and ossified frontal, pterotic, epiotic, exoccipital, basioccipital, preorbital, maxillary, hyomadibular, preopercle, opercle, hypohyal. Thirty-six days after hatching, the larvae were 15.26~16.39 mm (mean 16.11 mm) in TL and ossified scapula. 37 days after hatching, the larvae were 15.33~16.87 mm (mean 16.25 mm) in TL and ossified ethmoid, nasal, parietal, supraoccipital, and suborbital. Forty-five days after hatching, the larvae were 20.01~21.83 mm (mean 21.14 mm) in TL, and the shoulder girdle was completed by coracoid formation. Forty-eight days after hatching, the larvae were 22.46~24.03 mm (mean 23.20 mm) in TL and ossified articular and subopercle. When the juvenile reached 27.11~34.09 mm (mean 30.11 mm) in TL (53 days after hatching) completed ossification of the cranium, vertebrae, pelvic girdle, shoulder girdle, caudal bone, and pterygiophore.

• Journal of Life Science
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• v.12 no.4
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• pp.407-415
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• 2002

The survival of the early larvae of the freshwater crab, E. japonicus, fed on different diets at 22土1$^{\circ}C$ and 24$\pm$1% were studied in the laboratory. The larvae in the control (no feed) lived for 4 days (1~2 zoeal stages), and in the experimental container of non-living foods (egg Powder, soy bean Powder, Pellet Powder, millet Powder, and mussel meat), they were lived for 7~9 days (2~3 zoeal stages), When the larvae fed on phytoplankton (Chlorella ellipsoid., Skeletonema costatum. and Chaetoceros gracilis), they lived for 10, 18, and 19 days(3~5 zoeal stages), and fed on zooplankton (Artemianauplii and rotifer), they were reached to the juvenile stage in 24 and 25 days, respectivily. When the larvae fed on a mixed diets (see table 1). it was more effective than a single food diet, and the most effective diets included Chaetoceros gracilis, Artemia nauplii and rotifera, in which the larvae reached the juvenile stage in 22 days, and the survival was 73%.

• Development and Reproduction
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• v.20 no.2
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• pp.109-118
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• 2016

This study monitored the morphological development of embryo, larvae and juvenile yellowtail kingfish, Seriola lalandi, for their aquaculture. The fertilized eggs obtained by natural spawning were spherical shape and buoyant. Fertilized eggs were transparent and had one oil globule in the yolk, with an egg diameter of $1.35{\pm}0.04mm$ and an oil globule diameter of $0.32{\pm}0.02mm$. The fertilized eggs hatched 67-75 h after fertilization in water at $20{\pm}0.5^{\circ}C$. The total length (TL) of the hatched larvae was $3.62{\pm}0.16mm$. During hatching, the larvae, with their mouth and anus not yet opened. The yolk was completely absorbed 3 days after hatching (DAH), while the TL of post-larvae was $4.72{\pm}0.07mm$. At 40 DAH, the juveniles had grown to $30.44{\pm}4.07mm$ in TL, body depth increased, the body color changed to a black, yellow, and light gray-blue color, and 3-4 vertical stripes appeared. At 45 DAH, the juveniles were $38.67{\pm}5.65mm$ in TL and $10.10{\pm}0.94mm$ in body depth. The fish were green with a light orange color, with 7 faint green-brown stripes on the sides of their body. At 87 DAH, the juveniles had grown to 236.11 mm in TL, 217.68 mm in fork length, and 136.5 g in weight. The fish resembled their adult form, with a light yellow-green body color, loss of the pattern on the sides of their body, and a yellow coloration at the tip of the caudal fin.

• Korean Journal of Ichthyology
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• v.34 no.4
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• pp.244-252
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• 2022

The aim of this study was to investigate the early life history of Squalidus gracilis majimae by observing the development of the eggs and morphology of juvenile fish. Squalidus gracilis majimae used in this study were captured in 2021 June from a tributary flowing into Wicheon, located in Uiseong-gun, Gyeongsangbuk-do. For artificial insemination, ovaprim was injected at 0.5 mL/kg. Egg development occurred 12 h after injection. The size of mature eggs of S. gracilis majimae was 0.80~0.85 mm (0.83±0.01 mm, n=30). Incubation time at 22±1℃ ranged from 62.5 to 69 h. The length of larvae immediately after hatching was 2.39~2.53 mm (2.44±0.04 mm, n=30). On the 18th day after hatching, the larvae had a total length of 8.51~9.84 mm (8.95±0.42 mm, n=30), and the tip of the spine was completely curved. On the 22nd day after hatching, the juvenile fish had a total length of 12.6~13.6 mm (13.0±0.36 mm, n=30), with dorsal fins at iii7 and anal fins at i7. Egg size and hatched larvae size were similar for S. gracilis majimae and S. multimaculatus, and cupulae showed a singularity as it disappeared last among related species.

• The Korean Journal of Malacology
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• v.29 no.4
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• pp.263-272
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• 2013

The development of swift's scallop Chlamys swiftii, reared in the laboratory, has been examined through the investigation of morphological characteristics in fertilized egg, larvae and juvenile. Eggs were fertilized with a dilute sperm solution to improve the survival of fertilized eggs. Developing larvae were maintained at a temperature of $16{\pm}0.5^{\circ}C$ and salinity concentration of 33 ppt. We have investigated the fertilization rates and egg number spawned at several stimulating conditions such as sunlight exposure, air dry, seawater temperature rise ($5^{\circ}C$) and seawater temperature rise ($5^{\circ}C$) after exposure of air dry for spawning induction of swift's scallop Chamys swiftii. Stimulation treated with sunlight exposure and seawater temperature rise ($5^{\circ}C$) have shown the spawning number of 700,000-900,000 and 700,000-800,000 per individual, respectively while stimulation treated with seawater temperature rise ($5^{\circ}C$) after exposure of air dry have shown the high spawning number of 1,000,000-1,500,000 per individual. Survival rate of D-shaped larvae of swift's scallop put into the different seawater temperatures of $8^{\circ}C$, $12^{\circ}C$, $16^{\circ}C$, $20^{\circ}C$ and $24^{\circ}C$ has been 4.1%, 11.6%, 32.7%, 18.6% and 3.2%, respectively. Fertilized eggs with the diameter of $72{\mu}m$ developed into trochophore larvae of $103{\pm}3.8{\mu}m$ shortly after 35 hours and to D larvae of $129{\pm}10.4{\mu}m$ shell length within 72 hours. It took 336 hours to become initial Umbo-stage larva of $145{\pm}16.8{\mu}m$ shell length. Post larvae, which have been $197{\pm}13.6{\mu}m$ shell length, spontaneously have settled in the attachment substances. It have required 528 hours from fertilized eggs to early attached juvenile to become initial juvenile size of $245{\pm}15.8{\mu}m$ shell length.