• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.17-18
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• 2003

Although flounder is one of the most important marine fish for aquaculture in Korea, feeding the flounder in commercial farms depends mainly on moist pellet in which over 70% frozen fishes (e.g. frozen horse mackerel) are incorporated in its formulation. Therefore, for further expansion of flounder farming, it is essential to employ practical formulated feeds that can support reasonable growth. Development of nutritionally balanced and cost-effective feeds is dependant on the information about nutritional requirement and feed utilization of the species. Nutrient and energy source in feed are needed for the growth and maintenance of fish. Protein is probably the most important nutrient affecting fish growth and feed cost. Therefore, it is essential to determine the optimum dietary protein level for the growth of fish, both its high proportion in the feed and because it is the main factor in determining feed cost. Dietary energy level is also critical because protein source in the feed is utilized as an energy source when the feed deficient in energy is fed to fish, whereas when the feed excess in energy is fed to fish, feed consumption decreased and resulted in growth reduction due to lack of other necessary nutrients for normal growth. Improper dietary protein, energy levels and/or their ratio will lead to an increase of fish production cost and deterioration of water quality resulting from wasted feed; thus, they are important in formulating commercial feed. Dietary lipids play important roles in providing energy and essential fatty acid for normal growth and survival of fish. Although carbohydrates are not essential nutrients for carnivorous fish, these compounds play important roles as a low-cost energy source for protein sparing and also as a feed binder. Nutrition researches for flounder have identified its requirements of protein, lipid and essential fatty acid, vitamin, and minerals for normal growth. Other studies have also been carried out to investigate the utilization of the protein, lipid and carbohydrate sources. Based on these nutritional information obtained, practical feed formulations have been studied for improve aquaculture production of flounder. The results of the researches on utilization of dietary protein, lipid and carbohydrate by flounder are discussed in this review.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.454-458
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• 2015

This study compared the effects of dietary supplementation of citrus by-product (CBP) and CBP fermented with Bacillus subtilis (F-CBP) on growth performance, feed utilization, intestinal histology and innate immunity of red seabream Pagrus major with three commercial immune-boosting products. The six experimental diets were supplemented with L-ascorbyl-2-polyphosphate (LAPP; the control diet), CBP or F-CBP at a concentration of 100 mg vitamin C equivalent/kg diet or one of three commercial immune boosters. The Experimental diets were fed to triplicate groups of 17 fish (initial body weight, 116 g) for 8 weeks. The water temperature during the feeding trial was maintained at $13-15^{\circ}C$. Growth and feed utilization did not differ significantly among the six dietary treatments, nor did the phagocytic activity, superoxide dismutase or total immunoglobulin concentrations. However, myeloperoxidase activity was significantly higher in the CBP groups. For the intestinal histology, the intestine diameter, villi and enterocyte heights and number of goblet cells did not differ significantly among groups. Therefore, CBP or F-CBP can be used as a valuable eco-friendly byproduct in diets for fishes including red seabream to maintain their normal growth and health.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.506-514
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• 2020

We investigated seed management and feeding regime of larval red spotted grouper Epinephelus akaara using live food organisms. Fertilized eggs were produced in March 2020 by manipulating photoperiod and water temperature. Broodstock (F0) produced approximately 0.30×10⁶ eggs, of which 0.25×10⁶ were fertilized; first-generation broodstock (F1) produced 2.00×10⁶ eggs, of which 1.90×10⁶ were fertilized. Larvae were reared at temperatures of 21.0-24.5℃. The feeding regime consisted of rotifers Artemia, and commercial pellet feed. From 5-8 days after hatching (dah), rotifers collected from high-density incubation tanks were fed to grouper larvae at a density of 10-20 individuals/mL. From 9-30 dah, rotifers collected from low-density incubation tanks were fed to larvae at a density of 10-20 individuals/mL. Newly hatched Artemia were provided from 20-24 dah and enriched Artemia from 25-50 dah. Commercial pellet feed was given starting at 13 dah. The average mouth size in hatchlings was 263.4±3.7 ㎛ at 5 dah, 406.7±21.0 ㎛ at 11 dah, and 856.9±136.6 ㎛ at 21 dah. At 1 dah, larvae had a mean total length of 1.95±0.06 mm. At 66 dah, the mean TL was 4.0 cm. The final number of surviving red spotted grouper larvae was 218,380 fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.5
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• pp.291-297
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• 2005

This study evaluated the quality of commercial extruded pellet (EP) diet of five companies (A, B, C, D and E) for olive flounder Paralichtys olivaceus by biochemical analyses, physical properties and growth performance. The proximate analyses of five EP diets showed $3.2-10.0\%$ of moisture, $49.3-55.5\%$ of crude protein, $4.6-14.7\%$ of crude lipid, $7.0-13.8\%$ of crude ash, $0.7-10.5\%$ of crude fiber, $10.0-27.3\%$ of itrogen free extract (NFE), 304.3-395.4kcal/100g of digestible energy (DE) and 6.1-7.1 of calorie/protein ratio (C/P). Peroxide value (POV) was highest in diet D (47.4 meq/kg) as compared to other diets which in the range of 4.0-11.7 meq/kg. Total amino acid contents were ranged from 46.54 to $55.46\%$ with the highest content in diet B and the lowest content in diet C. Essential amino acid of diet C was lowest $(7.43\%)$ as compared to other diets which in the range of $19.43-20.30\%$. Saturated fatty acid was higher in diet A $(37.65\%)$ followed by diet B $(36.32\%)$, diet E$(34.39\%)$, diet C$(30.95\%)$ and diet D$(30.10\%)$. EPA+DHA were highest in diet E$(30.78\%)$ and lowest in diet C$(15.48\%)$. The floating rate after 6 hours on the sea water was highest in diet C$(100\%)$ followed by diet B$(40\%)$ and A$(10\%)$. However, diets D and E were completely settled down after 1 and 2 hours, respectively. The range of relative expansion rate was $27.2-49.3\%$ for all diets and all reached the peak at 2-3 hours. The water absorption rate of diets C and D was lowest, and diet E was highest at 1 hour after deposition of sea water. Growth rate was higher in diet B$(22.3\%)$ and E$(21.3\%)$. Feed efficiency was higher in diet A$(109.7\%)$ and E$(105.3\%)$ and was significantly lowest in diet D$(80.7\%)$. The protein efficiency ratio was highest in diet E (2.72) and lowest in diet D (1.76). These results suggest that there is a necessity for improvement of nutrients balance and feed physical properties to fulfill the nutrient requirements and digestive characteristics of fishes in commercial EP diets.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1244-1247
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• 2007

Effects of muscle fluid concentrates from Styela clava on fish diets were investigated in rainbow trout(Oncorhynchus mykiss). Fish were fed on one of the isonitrogenous(48%) and isolipic(20%) feed containing 5 to 20% of muscle fluid concentrates for 8 weeks. Hematological parameters such as hemoglobin, hematocrit, albumin, glucose, total bililubin, triglyceride and glutamic pyruvate transaminase of the rainbow trout which were fed on the diets varied, but no specific trend became apparent. However, glutamic oxaloacetic transaminase value was significantly higher than that of normal fishes. Therefore, concentrated ascidian fluid which is normally discarded, can be combined with commercial diets for the normal growth of rainbow trout.

• Preventive Nutrition and Food Science
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• v.20 no.1
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• pp.67-72
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• 2015

Squid is one of the most important commercial fishes in the world and is mainly utilized or consumed as sliced raw fish or as processed products. The biofunctional activities of enzymatic squid meat hydrolysate were determined to develop value-added products. Enzymatic squid hydrolysate manufactured by Alcalase effectively quenched 1,1-diphenyl-2-picrylhydrazyl radical, hydroxyl radical, and hydrogen peroxide radical with $IC_{50}$ values of 311, 3,410, and $111.5{\mu}g/mL$, respectively. Angiotensin I-converting enzyme inhibitory activity of squid hydrolysate was strong with an $IC_{50}$ value of $145.1{\mu}g/mL$, while tyrosinase inhibitory activity with an $IC_{50}$ value of 4.72 mg/mL was moderately low. Overall, squid meat hydrolysate can be used in food or cosmetic industries as a bioactive ingredient and possibly be used in the manufacture of seasoning, bread, noodle, or cosmetics.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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• pp.6-10
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• 1986

The feasibility of passive detection of fishes which had been caught in the fishing grounds near the Korean peninsula was theoretically investigated. Considering the commercial importance and the acoustical informations readily identified, although many species of fish make noise, Croaker is clarified to be a representative fish for passive fish detection. Assuming a source level of the sound produced by croakers is given as 150-18OdB (re 1l'pa, 500 Hz bandwidth), The range detected by a passive line array sonar is estimated to be about 3-20km. In addition, the tonal noise (700~800Hz) made by croaker that is easily separated from underwater noise is expected to increase the ability to discriminate from the other species of fish.

• Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.167-174
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• 2022

Despite the beneficial aspect of fish consumption, bioaccumulation of toxic metals such as arsenic (As) and mercury (Hg) can enhance the health risk for the consumers. Arsenic and Hg concentrations were measured in edible tissue and two targeted organs, namely gill and liver of longtail tuna species (Thunnus tonggol) from Terengganu waters, including Kuala Besut, Kuala Terengganu, Dungun and Kemaman. The concentration of As and Hg were analysed by using inductively coupled plasma- mass spectrometry. The mean concentrations of both elements were significantly different (p < 0.05) among the locations and targeted organs. The hierarchy of As and Hg mean concentrations in muscle samples were Dungun > Kuala Besut > Kemaman > Kuala Terengganu. The mean concentration of As in all samples, including muscle, exceeded the permitted level set by Malaysia Food Act. Estimate Weekly Intake (EWI) was conducted to assess the health risk effect, and 63 kg was used as the average body weight of Malaysian adults. However, the EWI values show that the weekly intake of As and Hg does not exceed the provisional tolerable weekly intake limit suggested by Food and Agricultural Organization for the United Nations and is considered safe to be consumed.

• Journal of Food Hygiene and Safety
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• v.32 no.1
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• pp.42-49
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• 2017

The aim of this study was to determine total mercury and methyl mercury level in fishes (Deep-sea Fish, Tuna, Billfish) and fishery products. A total of 101 fishes and 44 fishery products samples collected from commercial market in Gyeonggi-do. Total mercury were analysed by mercury analyzer and methyl mercury were analyzed by gas chromatography with electron capture detector. In the fishes, total mercury was detected in all samples and methylmercury was detected in 92 samples of them. The detection rate of methylmercury was 91.1% in fishes. The mean concentration (mg/kg) of total mercury and methylmercury were $1.968{\pm}0.505/0.496{\pm}0.057$ for Billfish, $0.665{\pm}0.091/0.252{\pm}0.033$ for Deep-sea Fish and $0.577{\pm}0.085/0.218{\pm}0.025$ for Tuna, respectively. The Swordfish contains the highest level of total mercury (1.968 mg/kg) and methylmercury (0.496 mg/kg). In Mabled rockfish, the ratio of methylmercury's contents about total mercury's contents was the highest as 66.5%. In case of fishery products, frozens made of 100% of raw material contained the highest level of total mercury and methyl mercury. The weekly intake of total mercury and methylmercury was calculated in 4.72% and 5.24% of Provisional Tolerable Weekly Intake (PTWI) respectively. This study showed that the weekly intake of methylmercury from Deep-sea Fish, Tuna and Billfish was less than the PTWI recommended by the Joint FAO/WHO expert committee on food additives.

• Korean Journal of Ichthyology
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• v.19 no.4
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• pp.318-323
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• 2007

The feeding habits of Pacific cod (Gadus macrocephalus) were studied based on the examination of stomach contents of 192 specimens collected from November, 2005 to January, 2006 in the coastal waters off Gadeok-do, Korea. The size of Pacific cod ranged from 35 to 82 cm in standard length (SL). Pacific cod mainly consumed shrimps such as Eualus spathulirostris, Crogon hakodatei and C. affinis and fishes. Its diet also included small quantities of cephalopods, amphipods, hermit crabs and crabs. Individuals between 35 cm and 45 cm SL mainly consumed shrimps. The portion of shrimps decreased with increasing fish size, and this decrease was paralleled with increased consumption of fishes and cephalopods. In this study we found Syngnathus schlegeli in the stomach contents of many Pacific cod specimens. S. schlegeli is a typical seagrass fish species which inhabits in seagrass beds, This fact means that Pacific cods stay in the seagrass beds during spawning period. Therefore migration of Pacific cod to coastal waters off Gadeok-do during spawning period seems to be a survival strategy for its larvae and small juveniles to stay in seagrass beds which provide with abundant foods and shelters to many commercial fish species.