• Korean Journal of Ichthyology
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• v.23 no.4
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• pp.278-287
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• 2011

Habitat environment, age and feeding ecology of Gobiobotia macrocephala were investigated to provide baseline data for ecological characteristics and recovery in the Seom River at Heungho- ri, Buron-myeon, Wonju-si, Gangwon-do, Korea from 2010 to 2011. G. macrocephala inhabited 10~40 cm in water depth, 8~20 cm bottom size and 40~120 cm/sec in current velocity, and pebble floor were factors to be important for inhabit density. Age group of G. macrocephala in May estimated from the standard length indicated that the 28~42 mm group is 1 year old, the 43~58 mm group is 2 years old, the 59~69 mm group is 3 years old and the 69~85 mm group is more than 4 years old, and the female was 4~10 mm larger than the male. G. macrocephala did mainly feeding with nocturnal fishes between 00 h to 06 h, and they fed mainly Trichoptera (57.7%), Diptera (26.0%) and Ephemeroptera (16.3%). And their small juvenile fed mainly Ephemeroptera and Diptera, however, they ate mainly Trichoptera while growing to adult fish.

• Development and Reproduction
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• v.20 no.2
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• pp.65-79
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• 2016

We observed the osteological development of larval and juvenile red spotted grouper (Epinephelus akaara) in order to generate data for the assessment of skeletal deformities and to inform phylogenetic systematics research. Larvae and juveniles were obtained from a aquafarm in Muan-gun, Jeolla-namdo Province, Korea. The average water temperature at the time of breeding was $23.0^{\circ}C$ and average water salinity was 33.0 psu. Freshly hatched fish larvae had not undergone any ossification, but ossification of the parasphenoid bone, which forms the base of the cranium, occurred as the juveniles reached an average body length (BL) of 2.49 mm. At the same time, ossification of the preopercle and opercle occurred in the operculum, and ossification of the maxilla, which forms the upper jaw, and the dentary bones, which form the lower jaw, began. In addition, ossification of the vertebra occurred by formation of 7 vertebral centra and the neural spine in the abdominal vertebra. When the juveniles reached an average (BL) of 5.22 mm, ossification of the nasal, lateral ethmoid, and alisphenoid bones occurred in the cranium; ossification of the endopterygoid and metapterygoid bones began in the palatine region; and ossification of the hypohyal and interhyal bones occurred in the hyoid arch. At an average (BL) of 20.9 mm, ossification of the basisphenoid bone in the cranium and the suborbital bone in the orbital region occurred. Ossification of the vertebra then occurred by the formation of long pairs of ribs from the third to the ninth abdominal vertebrae, completing osteological development.

• Journal of Aquaculture
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• v.15 no.2
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• pp.103-110
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• 2002

Diets containing 0.02 to 10.0% EM-fermented orange (EFO) were fed to Paralichthys olivaceus(8.5 g), which were reared in flow-through system for 16 weeks. Groups fed on diets containing 0.1 and 0.2% EFO grew significantly faster; their feed coefficient and daily feeding rate were also higher. The number of goblet cells present in the mid-intestine of the fish receiving dietary EFO was significantly more. Total cholesterol level in plasma of the fish fed with 0.02% EFO was lower. However, there was no significant difference in GOT and GPT among the groups receiving different levels of EFO.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.478-484
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• 2004

On 11 June 1991, eggs from the brood stock of small yellow croaker (Larimichthys polyactis) were artificially fertilized using the standard dry method and were hatched. Each of the fertilized eggs (1.1-1.2 mm in diameter) had an oil globule and was transparent and buoyant. The fertilized eggs hatched in a range of water temperatures $(17.5-20.3^{\circ}C)$ 44 hrs after fertilization. The total lengths of the newly hatched larvae were 3.1-3.3 mm, and these hatchlings had 31 myotomes (10+21). Melanophores and yellow-brown chromatophores were concentrated on the head, at the ventral part of the yolk, and in the middle of the tail. Four days after hatching, the larvae completely absorbed the yolk and became flexions of 5.1-5.5 mm in total length. Fifteen days after hatching, one spine (the anterior tip of the maxillary) appeared in the upper jaw and three spines developed at the upper parts of the eyes and on the posterior part of the head. At this stage, the larvae were approximately 8.3 mm long. Thirty-nine days after hatching, juveniles (1.9-3.4 mm in total length) had a pointed tail fin. By 66 days after hatching, the juvenile fish (about 4.0-6.5 mm in total length) were similar to adult fish in body shape. The larvae of L. polyactis could be distinguished from those of L. croacea by two distinct characteristics: the large number of vertebrae (28-29), and a relatively small bony ridge on the occipital region of the head.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.74-82
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• 2020

Dragonet fish (Callionymidae), living in benthic upper 900 m of all subtropical, tropical and temperate oceans, comprises 200 species in 20 genera worldwide, of which 18 species in 6 genera occur in Korea. Although dragonet fish plays an important role in linking between top predators and lower trophic levels, there are only few studies about their early life history. Herein, we present molecular and morphological data on larvae and juveniles of Bathycallionymus kaianus (Günther, 1880) collected from the Korean waters. During 2016 to 2018, one preflexion larvae [2.69 in total length (TL)], three flexion larvae (3.65 and 4.77 mm TL), six postflexion larvae (6.07 and 7.94 mm TL), and three juveniles (10.81 and 12.26 mm TL) were collected in the East Sea, Korea Strait, and Jeju Island using Bongo net. Of them, 13 individuals were identified through molecular markers (COI or 16S rRNA) and morphologically described. The larvae of B. kaianus are well distinguished from other species of Callionymidae in melanophore distribution, body shape and development of preopercular spine. It was very similar to larvae of two Repomucenus species, R. valenciennei and R. virgis, but was clearly distinguished in melanophore distribution, preopercular spine development, and head shape.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.371-378
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• 2011

Juvenile red seabream (mean body weight 29.0 g) were reared in recirculating culture systems with three different biofilter media, sand (SF), polystyrene microbeads (PF), and Kaldnes beads (KF). The efficiencies of the three different biofilter media were also tested. The SF was fluidized, and the PF and KF were trickled. All treatments were duplicated. The volumetric removal rates of total ammonia nitrogen by SF, PF, and KF were 193.8, 183.9, and 142.6 g $m^{-3}day^{-1}$, respectively, and those of nitrite nitrogen ($NO_2$-N) were 113.4, 105.9, and 85.8 g $m^{-3}day^{-1}$, respectively. The TAN and $NO_2$-N removal rates of KF were lower than those of SF and PF (P < 0.05), but there was no significant difference in these rates between SF and PF (P > 0.05). Among the biofilters used, only KF showed total suspended solid (TSS) removal capacity. The TSS removal efficiencies of SF and PF were negative. The growth rates of fish in SF were significantly higher than those in KF but not higher than those in PF. There was no difference in growth rate between fish in PF and KF. The specific growth rate and feed conversion efficiency of red seabreams in KF were lower than those in SF and PF, but there were no significant differences between SF and PF. These results indicate that sand and polystyrene microbeads are recommended for red seabream culture in a recirculating system.

• Fisheries and Aquatic Sciences
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• v.20 no.9
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• pp.20.1-20.8
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• 2017

The objective of this study was to examine the effect of dietary supplementation of taurine for juvenile olive flounder (Paralichthys olivaceus) at low water temperature ($16.4{\pm}0.36^{\circ}C$). Fish meal (FM)-based diet was used as the control diet. Four other experimental diets were prepared by adding taurine to FM-based diet at 0.25, 0.50, 1.00, and 1. 50% (T1, T2, T3, and T4, respectively). Each experimental diet was fed to triplicate groups of fish (initial mean body weight, 19.5 g) for 10 weeks. At the end of the feeding trial, growth performance and feed utilization, hematological parameters, non-specific immune responses, whole-body proximate composition, and liver mRNA expression of insulin-like growth factor-1 (IGF-1) were investigated. Feed conversion ratio was significantly reduced while protein efficiency ratio was significantly increased in taurine-supplemented groups. Hematocrit and hemoglobin were also significantly increased while plasma cholesterol levels were decreased in taurine-supplemented groups than those in the control group. Nitroblue-tetrazolium, myeloperoxidase and lysozyme activities, and plasma immunoglobulin level were significantly increased by taurine supplementation. These results suggest that dietary taurine supplementation is effective in improving growth performances, feed utilization, and innate immunity of olive flounder in low water temperature season.

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.92-99
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• 2018

Feeding ecology of endangered Korean endemic miho spine loach, Cobitis choii, was investigated in Jicheon Stream, Geumgang River, Korea to provide ecological characteristics and baseline data for its restoration. C. choii is active during daylight hours above sand from March to October when the water temperature exceeded $13^{\circ}C$, but tended hibernate in the stream bottoms (sand) in the winter months (November~February) when the water temperature was lower than $13^{\circ}C$. They fed (index of relative importance, IRI) mainly Diptera (69.9%), Copepoda (23.2%), Arcellidae (2.3%), Branchiopoda (2.0%) and Ploima (2.0%). And their small juvenile (age 0+) fed mainly small size, Ploima and Branchiopoda, however, they ate mainly large size, Chilonomidae, while growing to adult fish (age 2+~3+).

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.369-378
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• 2018

This study was conducted to evaluate effects of dietary microbial probiotics on the growth and disease resistance of olive flounder (Paralichthys olivaceus) in a recirculating aquaculture system (RAS), and the effects of the probiotic bioaugmentation on the microbial community structure and water quality. For the analysis, 80 juvenile fish (average weight, $25.7{\pm}7.6g$; average length, $15.2{\pm}1.7cm$) were fed a basal diet containing a commercial microbial product CES-AQ1 (CES; $1{\times}10^9\;CFU/kg$ diet) in an RAS for 8 weeks. Weight gain, the specific growth rate, feed efficiency, and protein efficiency ratio of the fish fed the CES diet in the RAS were 1.5~2.5 times higher than those of fish fed the basal diet alone, or the basal diet containing oxytetracycline (OTC), yeast plus bacterium, or Bacillus subtilis in a still water system. There was no significant difference in the pathogen challenge test between fish fed the OTC diet and fish fed the CES diet in the RAS, suggesting the CES-AQ1 probiotic used in the RAS as a potential replacement for antibiotics. The RAS biofilter maintained the highest microbial diversity and appeared to harbor microbial communities with ammonium oxidation, denitrification, and fish pathogen suppression functions. Ammonia, which is hazardous to fish, was significantly decreased to < 0.5 mg/L in 19 days, indicating the effectiveness of probiotic supplementation to maintain good water quality in RAS. These results suggest that the intestinal microbial communities of fish are stabilized by a probiotic-containing diet (CES) and that bioaugmentation with probiotics may be an eco-friendly and economical supplement for aquaculture of olive flounder, promoting both good water quality and fish health in an RAS.

• Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.301-309
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• 2015

Chub mackerel, Scomber japonicus, larvae and juveniles were reared from hatching to 35 days after hatching (DAH), and the development of their digestive systems was histologically investigated. The larvae were initially fed on rotifers and Artemia nauplii starting around 19 DAH, and thereafter on Artemia nauplii, fish eggs, and a formulated feed mixture. The primitive digestive system differentiated at 3 DAH; the digestive tract was distinctively divided into the buccopharyngeal cavity, esophagus, stomach, air bladder, intestines, and rectum. The gastric gland and pyloric caeca first appeared at 5 and 7 DAH, respectively. The stomach was divided into cardiac, fundic, and pyloric regions in the preflexion phase. The number of gastric glands and pyloric caeca, as well as the volume of the gastric blind sac increased markedly, with development continuing into the juvenile stage. The precocious development of the digestive system during the larval period might be related to the early appearance of piscivory, which is able to support high growth potential. The organogenesis results obtained for this precocial species represent a useful tool to aid our understanding of the physiological requirements of larvae and juveniles to ensure optimal welfare and growth under aquaculture conditions, which will improve current rearing practices of this scombrid species.