• Journal of Aquaculture
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• v.12 no.3
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• pp.237-245
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• 1999

In this study, we evaluated the efficiency of chemical marking of black rockfish scales by immersion in oxytetracycline hydrochloride (OTC, 500 ppm), alizarin red S (AR, 250 ppm) and calcein (CARL, 250 ppm) diluted rearing water. Immersion treatment of chemicals had no effects on both mortality and growth of black rockfish. Marking sucess was 100% in all treatment durations (24, 48 and 72 hours) with three chemicals and marking quality was higher in 48 and 72 hours than 24 hours treatment. Marking retention rates at 24 weeks after treatment were 100% in OTC and CAL treated group, but marking quality was higher in CAL treated group (brilliant 92%, bright 8% and dim 0%) than in OTC treated group (brilliant 4%, bright 70% and dim 26%). AR treated group had lower marking retention rates and marking quality than OTC and CAL treated group. As a results, immersion treatment with OTC and CAL was effective in marking scales of black rockfish and practical in releasing program and other studies requires same rearing environment.

• Proceedings of the Korean Aquaculture Society Conference
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• 2001.12a
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• pp.280-281
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• 2001

• Ocean and Polar Research
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• v.23 no.3
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.

• Fisheries and Aquatic Sciences
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• v.24 no.9
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• pp.311-317
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• 2021

Inclusion effect of various levels of jack mackerel meal (JMM) acting as feed attractants and/or stimulants in diets on the growth, feed consumption, feed utilization and whole body composition of rockfish was investigated. Three hundred juvenile rockfish were randomly allocated into 15 flow-through tanks. Five experimental diets supplemented with JMM at 0%, 1%, 3%, 5%, and 10% at the expense of anchovy meal were prepared and referred to as the JMM0, JMM1, JMM3, JMM5, and JMM10 diets, respectively. Weight gain, specific growth rate (SGR) and feed consumption of fish tended to improve with dietary levels of JMM. The greatest weight gain, SGR and feed consumption were observed in fish fed the JMM10 diet, followed by the JMM5, JMM3, JMM1, and JMM0 diets, in that order. Condition factor (CF) of fish tended to improve with dietary inclusion levels of JMM. Growth performance, feed consumption and CF of fish tended to improve with dietary inclusion levels of JMM ranging from 0% to 10%.

• Journal of Aquaculture
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• v.9 no.3
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• pp.247-254
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• 1996

Two experiments were conducted to evaluate dry pellet on growth of juvenile Korean rockfish (sebastes schlegeli) by comparing with moist pellet and raw fish-based moist pellet. In the first experiment, three replicate groups of 40 fish averaging 4.7 g were fed one of the following three experimental diets for 11 weeks : d교 pellet (DP) and moist pellet (MP) diets containing $56\%$ white fish meal (WFM) + $3\%$ soybean meal (SM) + $5\%$ corn gluten meal (CGM) as protein sources, or raw fish-based moist pellet (RMP, $50\%$ frozen horse mackerel+$50\%$ commercial fish feed). No significant differences were found among fish fed different pellet types of diets in daily weight gain and whole body composition (P>0.05). In the second experiment, two replicate groups of 140 fish averaging 10.9 g were fed one of the following three experimental diets for 8 weeks : DP and MP diets containing $38\%$ WFM+$15\%$ SM+$10\%$ CGM as protein sources, or RMP. Daily weight gain and feed efficiency from fish fed RMP were significantly (P>0.05) higher than those from fish fed DP diet. These different growth responses between two experiments may be due to dietary protein sources and nutrient content. findings showed that DP can be used as a practical diet for juvenile Korean rockfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.609-613
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• 2009

This study was conducted to investigate the effects of dietary supplementation of $\beta$-1,3 glucan on growth, hematological and body composition in juvenile korean rockfish, Sebastes schlegeli fed the white fish meal based diets for 6 weeks. Four experimental diets were formulated to contain control (without supplementation of glucan), 0.05%, 0.1% and 0.5% (this diet was fed to fish daily, bi-weekly as three different dietary treatments) $\beta$-1,3 glucan per kg diet (Control, $D_{0.05}$, $D_{0.1}$, $D_{0.5}$, $B_{0.05}$, $B_{0.1}$, $B_{0.5}$). Fish averaging $4.0\pm0.1g$ (mean$\pm$SD) were randomly distributed in each aquarium as triplicate groups of 23 fish. Weight gain (WG, %) and specific growth rate (SGR, %) of fish fed $D_{0.5}$ diet were significantly lower than those of fish fed the other diets (P<0.05). Feed efficiency (FE) of fish fed $B_{0.05}$ diet was significantly higher than those of fish fed $D_{0.1}$, $D_{0.5}$, $B_{0.1}$ and $B_{0.5}$ diets (P<0.05). Protein efficiency ratio (PER) of fish fed $B_{0.05}$ diet was significantly higher than those of fish fed $D_{0.1}$ and $D_{0.5}$ diets (P<0.05). According to the results, the supplementation of 0.05% $\beta$-1,3 glucan daily and/or biweekly is optimum in juvenile Korean rockfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.761-768
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• 2013

We conducted two feeding trials to investigate the optimal feeding frequency of juvenile Korean rockfish Sebastes schlegeli fed a commercial diet of expanded pellets containing 47.2% crude protein, 9.2% crude lipid, and 14.5% ash at two different water temperatures. In the first experiment, triplicate groups of 20 fish with an average weight of 2 g were fed an equal amount of diet (5.97% based on body weight) at one of six feeding frequencies (2, 3, 4, 5, 7, or 9 meals/day) for four weeks at $17.5^{\circ}C$. After four weeks, we measured weight gain (WG), specific growth rate (SGR), feeding efficiency (FE), and protein efficiency ratio (PER). Fish fed diet five meals/day grew significantly better than those fed nine meals/day. The second experiment used identical experimental conditions and feeding regions, except the food ration was slightly less (5.92% based on body weight) and the water temperature was increased to $20^{\circ}C$. After four weeks, we again measured WG, SGR, FE and PER. Fish fed seven meals/day grew significantly faster than those fed 2, 3, 4, or 9 meals/day. Whole-body protein levels in fish fed three meals/day was higher than those fed four meals/day in $17.5^{\circ}C$ water, but whole-body lipids in the fish fed four meals/day was higher than those fed two meals/day in $20^{\circ}C$ water. A second-order polynomial analysis based on WG suggested the optimal feeding frequency for juvenile Korean rockfish was five meals/day at $17.5^{\circ}C$ and six meals/day at $20^{\circ}C$, indicating that fish reared in higher water temperature require higher feeding frequencies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.753-760
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• 2013

Two feeding trials were conducted to investigate the effects of feeding rate and frequency on growth performance and body composition of juvenile Korean rockfish Sebastes schlegeli reared at $15.0{\pm}0.3^{\circ}C$. In the first trial, three replicate fish groups averaging $2.07{\pm}0.03g$ were fed a commercial diet with one of seven different daily feeding rates: 1.00%, 2.00%, 2.50%, 2.75%, 3.00%, 3.25%, and satiation (3.34%) based on body weight (BW). After four weeks of feeding, fish fed the 3% diet showed significantly higher weight gain (WG) and feed efficiency (FE) than fish that received the other feeding rates. In the second trial, the optimum feeding frequency was evaluated with three replicate fish groups averaging $2.04{\pm}0.03g$. Fish were fed a commercial diet at 2.87% BW with six different daily feeding frequencies: 2, 3, 4, 5, 7, or 9 meals. After four weeks of feeding, WG, specific growth rate, FE, and protein efficiency rate in fish fed 3 meals $d^{-1}$ were significantly higher than those of fish fed 7 or 9 meals $d^{-1}$. In both feeding trials, proximate composition of the entire body changed depending on the feeding rate or frequency. A broken-line regression analysis based on weight gain suggested that the optimum daily feeding rate and frequency for juvenile Korean rockfish at $15^{\circ}C$ was 2.9% BW $d^{-1}$ and 2-3 meals $d^{-1}$, respectively.

• Journal of Aquaculture
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• v.10 no.3
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• pp.255-260
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• 1997

In order to investigate the effects of phosphorus and iron levels in the diets containing fish meal as only protein source on the growth, feed conversion, body composition and blood characteristics of juvenile Korean rockfish, either graded monobasic potassium phosphate (MPP) of 1% (MPP-1), 2% (MPP-2), 3% (MPP-3) and 4% (MPP-4), or Fe-citrate (FC) of 0.022% (FC-1), 0.044% (FC-2), 0.066% (FC-3) and 0.088% (FC-4) was added to fish meal-based diet (MMP-0 or FC-0), respectively. Duplicate groups of 40 fish weighing 7g were fed the diets for 21 weeks. Weight gain, feed efficiency and nutrient retention of fish fed diets with different MPP levels were not significantly different (P>0.05). Lipid content of whole body decreased with an increase in dietary MMP (P<0.05). No significant differences were found in the Ht, Hb, total protein, or total glucose in serum among diets containing different MMP levels (P>0.05). Weight gain of fish fed the FC-0, FC-1 adn FC-3 diets was significantly higher than that of FC-4 diet (P>0.05), whereas feed efficiency, nutrient retention, hematological values (Ht, Hb, total protein, and total glucose), and whole body composition were not affected by dietary FC levels (P>0.05). The present results revealed that phosphate or iron supplementation to the diet containing 65% fish meal for juvenile Koran rockfish was not necessary.

• Ocean and Polar Research
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• v.31 no.3
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• pp.231-238
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• 2009

A study was carried out to investigate the effect of water temperature on daily pattern and rate of total ammonia nitrogen (TAN) excretion in juvenile dark-banded rockfish Sebastes inermis (mean body weight: $14.8{\pm}0.3g$) under fasting and feeding conditions. Fish were acclimated over 10 days under three different water temperatures (15, 20 and $25^{\circ}C$). After 72 hours of starvation, fasting TAN excretion was measured at each temperature. To investigate post-prandial TAN excretion, fish were hand-fed with a commercial diet containing 47.7% crude protein for 7 days, two times daily at 09:00 and 17:00 hr. Water was sampled from both the inlet and outlet of each chamber every 2 hrs over a 24 hr period. Both fasting and post-prandial TAN excretion increased with increase in water temperature (P<0.05). Mean fasting TAN excretion rates at 15, 20 and $25^{\circ}C$ were 8.1, 9.0 and 9.2 mg TAN kg $fish^{-1}h^{-1}$, respectively. The value of $15^{\circ}C$ was lower than those of 20 and $25^{\circ}C$ (P<0.05), but there was no significant difference between $20^{\circ}C$ and $25^{\circ}C$ (P>0.05). Mean post-prandial TAN excretion rates at 15, 20 and $25^{\circ}C$ were 20.1, 22.9 and 23.4 mg TAN kg $fish^{-1}h^{-1}$, respectively. A peak post-prandial TAN excretion rate occurred after 12 hrs from the first feeding at $15^{\circ}C$ (mean 28.7 mg TAN kg $fish^{-1}h^{-1}$), $20^{\circ}C$ (33.7 mg TAN kg $fish^{-1}h{-1}$) and $25^{\circ}C$ (36.8 mg TAN kg $fish^{-1}h{-1}$), respectively. The TAN loss for ingested nitrogen at $15^{\circ}C$ (36.2%) was lower than that of $20^{\circ}C$ (40.8%) and $25^{\circ}C$ (41.7%). Based on overall results, water temperature exerts a profound influence on the nitrogen metabolism of juvenile dark-banded rockfish.