• Journal of Aquaculture
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• v.11 no.3
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• pp.303-310
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• 1998

The growth and survival rate of larvae and juveniles from female rockfish (Sebastes schlegeli) broodstock in vitellogenesis by injection of 3,5,3'-triiodo-L-thyronine $T_3$ with a dose of 20 mg/kg fish wt. were examined for 30 days and compared with sham-control fish injected dime-thyl sulfoxide and control fish. Larvae were fed with rotifers for first 5 days after parturition, rotifers and Artemia nauplii for next 10 days. And then, they were fed with Artemia nauplii and commercial diet. Growth of larvae and juveniles from maternal $T_3$injection was significantly faster than that of two controls, nevertheless, the condition factor was lower than that of controls. The whole body proximate analyses indicated that there were significant effects of $T_3$ injection on protein and lipid, but no significant on moisture and ash contents. Survival rate of the fish from maternal $T_3$injection was significantly higher than that of fish from the two controls. These results indicate that thyroid hormone supplements appear to confer a distinct advantage to larval and juvenile rockfish in early, fragile development stage.

• Korean Journal of Ichthyology
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• v.12 no.4
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• pp.230-235
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• 2000

The purpose of the present study was to describe the morphological and skeletal development of the larvae and juvenile of Ilisha elongata(Bennett). The larvae(mean 5.02 mm in total length, TL) opened the mouth and anus with 36~38+15~16=51~54 myotomes, and anus located about 73.0% of TL. The clavicle of shoulder girdle was ossified. The larvae(mean 7.82 mm in TL) have all fin-fold differentiated and its caudal notochord began to flex. Parasphenoid of cranium and dentary of the lower jaw were ossified. The caudal notochord of the larva(mean 9.84 mm) was flexed $45^{\circ}$, and anus located about 67.0% of TL. The body height of the larvae(mean 23.32 mm in TL) were 18.0~20.0% of TL, and the aggregate numbers of all fin rays were completed. Ossification was completed in the larva of mean 26.52 mm in TL.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.111-116
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• 2009

Juvenile hormone (JH) is an insect hormone mediating immature metamorphosis and adult reproduction. It also mediates immune responses to suppress hemocyte behavior, which is, however, activated by ecdysteroid. This study investigated an effect of a commercial pyriproxyfen (a JH agonist) formulation on a cellular immune response of the diamondback moth, Plutella xylostella, and analysed its mixture with Bacillus thuringiensis (Bt) in insecticidal potency. The commercial pyriproxyfen formulation significantly suppressed hemocyte-spreading behavior at low doses as did in pyriproxyfen technical grade. When the commercial pyriproxyfen formulation was mixed with Bt, Bt toxicity was significantly increased against P. xylostella larvae in laboratory. The mixture effect was then confirmed in field cultivating cabbage infested with P. xylostella larvae. The mixture showed a significantly enhanced mortality and reduced effective lethal time, compared to only Bt treatment.

• Korean Journal of Ichthyology
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• v.34 no.1
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• pp.16-24
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• 2022

The eggs development and early life history of Sarcocheilichthys variegatus wakiyae was investigated. The adult fishes were collected in Yeongsangang River, Damyang-gun, Jeollanam-do, Korea, and their spawning inducement was carried by sex maturation hormone (Ovaprim) injections. Spawning amount was mean 31±3.5 Mature eggs were cicular in shape and mean 2.40±0.05 mm in diameter. Hatching period of the embryo was 230 to 240 hours after fertilization under water temperature of 22℃. The newly hatched larvae were 10.7±0.19 mm in total length (TL). 3 days after hatching, postlarvae was measured 12.0±0.13 mm in TL and the tip of the caudal fin was bent at 45°. 11 days after hatching, it was measured 14.6±0.13 mm in TL, and transferred to juvenile as the number of fins (iii7 dorsal fin, iii6 anal fin, i7 ventral fins) reached a constant number of each part.

• Development and Reproduction
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• v.18 no.4
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• pp.311-319
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• 2014

Newly hatched black porgy larvae (Acanthopagrus schlegeli) swam to the surface, with the mouth and anus still closed and were 1.90-2.11 mm (mean, 2.0 mm) in total length (TL). The larvae were 2.71-2.94 mm TL (mean, 2.82 mm) on day 2 after hatching. At this time, about two-thirds of the yolk was absorbed, the bladder and intestines had formed, and the mouth and anus were open. Total length was 4.32-4.66 mm (mean, 4.45 mm) at the post-larval stage on days 5-6 after hatching, and the yolk and oil globule were almost absorbed. The end of the notochord began to flex, and 6-8 caudal fin rays were visible. The larvae were 15.37-16.1 mm TL (mean, 15.83 mm) at the juvenile stage on days 30-32 after hatching, and the number of rays in all fins was completely revealed.

• Fisheries and Aquatic Sciences
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• v.23 no.7
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• pp.18.1-18.10
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• 2020

During June 2017, we collected two postflexion larvae (6.01 and 7.56 mm in standard length [SL]) and two juveniles (7.72 and 9.62 mm SL) belonging to Myctophidae in the waters of Jejudo Island. Those four individuals were identified as Diaphus garmani, which had not been reported in Korea. They were distinguished from Benthosema pterotum by melanophores in the abdominal cavity (absent in D. garmani vs. present in B. pterotum) and the development of photophores (developed in D. garmani vs. rudimentary in B. pterotum) when shorter than 10.0 mm SL. Analysis of 16S rRNA sequences showed that the sequences of four individuals matched those of adult D. garmani (Kimura 2-parameter distance: 0.6-0.8%). This is the first record of larvae and juveniles of D. garmani in Korean waters, and we propose a new Korean name, Gar-ma-ni-sat-bi-neul-chi.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.676-683
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• 2023

The development of the egg, larvae, and juveniles of Acheilognathus macropterus from the Wicheon stream of Nakdonggang River was investigated for early life history characteristics. The fish used in the study were collected from Wicheon stream located in Bian-myeon, Uiseong-gun, Gyeongsangbuk-do. The fertilized egg was 1.88±0.09 mm (n=30) in long diameter and 1.34±0.06 mm (n=30) in short diameter. After fertilization at a water temperature of 20℃, the egg took 31 h and 40 min to hatch. Newly hatched larvae had an average total length of 3.92±0.13 mm (n=30) and possessed a yolk sac the mouth and anus were not developed. Twenty days after hatching, the postflexion larvae had an average total length of 8.08±0.29 mm (n=30), with the tail tip fully bent at 45° and began feeding. Thirty-three days after hatching, the number of fin stems reached an integer with an average total length of 15.0±1.08 mm (n=30). In this study, differences in the egg size, hatching time, melanophore development period, and distribution location were confirmed between A. macropterus and allied species.

• Development and Reproduction
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• v.19 no.4
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• pp.189-196
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• 2015

This study was examined the ovogenesis of Ussurian bullhead, Leiocassis ussuriensis and the morphological development of its larvae and juveniles and to use the results as basic information for the preservation of species and resource enhancement. For artificial egg collection, human chorionic gonadotropin (HCG) was injected at a rate of 10 IU per gram of fish weight. During breeding period, water temperature maintained at $24.5{\sim}26.5^{\circ}C$ (mean $25.0{\pm}0.05^{\circ}C$). The process of ovogenesis reached the two-cell stage in 50 minutes after fertilization. In 73 hours of fertilization the movement of the embryoid body became active state and the larvae began to hatch from the tail through the oolemma. Length of prelarvae were 6.33~6.50 mm long (mean $6.40{\pm}0.06mm$) just after hatching having yolk with their mouth not opened. After thirty eight days of hatching, juveniles were 30.6~32.5 mm long (mean $31.5{\pm}0.65mm$). The color was dark yellowish brown throughout the entire body, and the number of caudal fin rays developed to thirty six perfectly.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.94-99
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• 2006

The tadpole larvae of most ascidians have two sensory pigment cells in their brain vesicle. The anterior otolith pigment cell is sensitive to gravity, whereas the posterior ocellus pigment cell responds to light. Besides these two sensory cells, the larvae also possess another type of sensory receptor cell: hydrostatic pressure receptor (Hpr) cells. The Hpr cells have been presumed to sense hydrostatic water pressure, although no functional analysis has been performed. In larvae of the ascidian Halocynthia reretzi, the development of the Hpr cells and their structure in the brain vesicle are poorly understood. To investigate the morphology and formation of the Hpr cells, we established a monoclonal antibody, Hpr-1, that specifically recognizes Hpr cells. The Hpr-1 antigens became detectable in the brain vesicle at the late tailbud stage. Each Hpr cell projected a small globular body, connected by a short stalk, into the lumen of the brain vesicle. The brain vesicle showed remarkable left-right asymmetry. Pigment cells were located on the right side in the lumen of the brain vesicle, whereas Hpr cells were present in the left side. After metamorphosis, the Hpr cells were observed near the rudimental siphons of the juvenile.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.56-62
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• 2009

Feeding regimens was investigated for the growth and survival rate of juvenile Maroon clownfish (Premnas biaculeatus) in order to establish a seed production technique for this fish. Three types of feeding regimens were used, and growth and survival were highest under the following regimen: rotifer from day 0, Artemia from day 4, copepod from day 9 and artificial food from day 15, respectively (P<0.05). The average body lengths of the larvae were $6.76{\pm}0.55\;mm$, $7.63{\pm}0.50\;mm$ and $7.33{\pm}0.43\;mm$ in the Nannochloropsis oculata, Isochrysis galbana and control treatments conducted with 3 larvae/L, respectively (P<0.05). There were significant differences in larval growth between the treatments and controls conducted with 6 larvae/L and 9 larvae/L, respectively (P<0.05) but there was no significant difference between the N. oculata and I. galbana treatments (P>0.05). There were no significant differences in larval growth between the treatments at densities of 3-9 larvae/L (P>0.05). At highest density level, the larvae reared in I. galbana had the highest survival rate whereas survival was lowest in the control.